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                                     V-61b
FIGURE V-10.
RELATIONSHIP BETWEEN THE ODDS OF COUGH
INCIDENCE VERSUS PM-10 CONCENTRATION FROM THE
SIX CITY STUDY (SCHWARTZ ET AL., 1994)
                  f
                  o
                  o
                  «-  T
                  o  ,_•
                  tn
                  •
                  a
                  Q)
                  cr
                                  20        40

                                      PM10 (ug/m3)
                                                     60
                        Relative odds of incidence of coughing smoothed against 3-d
                  mean PM,. (ng/m1), controOing tor temperature, city, day o» the week, and
                  ozone concentration.
FIGURE V-ll.
RELATIONSHIP BETWEEN PERCENT OF CHILDREN
REPORTING SYMPTOMS AND PM-10 IN UTAH VALLEY
(POPE AND DOCKERY, 1992)
                 MEAN % REPORTING RESPIRATORY SYMPTOMS FOR QUART1LES
                                     OF PM« LEVELS*
                                           Reporting
               No. of   PMlt
                               Symptomatic
                            Asymptomatic
        Quartile   Days  Meant  Upper  Lower Cough  Upper  Lower Cough
1
2
3
4
25
25
25
25
25
55
69
141
21
27
27
33
11
13
16
20
12
16
18
24
17
16
15
16
10
11
10
14
8
11
11
16
          • Tha quanta* wan faasad on feday moving avwagad Pl^ Wv*. «Mch canffad ftora13 to 208 w^i". wtth the l«t. 2nd. and
        3rd quartlte* equal to 39, 67, end 107 iig/m1. <««p«ctlv«ly.
                                         .
          t Thte «qu*b th« m»«n PM^ lev«< for the 25 days Jo *ad) quartto.

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External Review Draft                                                     Do Not Quote or Cite
November 1995                              V-62
relatively high particle concentrations.  The associations were stronger for children identified
as having a history of mild respiratory symptoms.  Figure V-l 1  shows the percent incidence
of health effects by quartile of PM,0.  Risk for all three respiratory symptom categories
increases consistently for children with symptomatic histories at  the second quartile of PMi0,
which averaged 55 jtg/m3, with risk not increasing in asymptomatic children until the fourth
quartile.
       b.    Sulfate Studies-
       Sulfates and acid aerosols have been reported in a number of studies to be associated
with respiratory hospital admissions, as summarized in Table V-9.  Two studies particularly
useful for assessing quantitative concentration-response relationships have reported an
association between sulfates and hospital  admissions for all ages while simultaneously
controlling for ozone (Burnette et al., 1994, 1995). In these studies, sulfates were reported
to be associated  with respiratory and cardiac hospital admissions in 168 hospitals across
Ontario. Figure V-12  shows a decile plot of daily respiratory admissions and sulfate level
from these studies. By inspection, this plot suggests that the observed risk for respiratory
hospital admissions becomes more clearly and consistently elevated within a concentration
range of 4-8 /tg/m3 as  sulfate. From a separate analysis, the daily average hospital admission
rates for respiratory and cardiac illness, associated with the third quartile of sulfate
concentrations (averaging 4.1 fig/m3) were reported to be significantly different from the
corresponding rate for the lower 50% of concentrations (averaging 1.5 /xg/m3) (Burnette et
al.,  1995).
       c.     TSP Studies
       A number of studies have been conducted examining the relationship between TSP
and various health endpoints, especially mortality.  In general, because of the inclusion of
non-inhalable particles within the TSP indicator, the CD .concludes that TSP is a less reliable
indicator for evaluating health effects of PM.  However^ because of the substantial amount of
daily air quality data for TSP and other pollutants available in Philadelphia, several
investigators have extensively  reanalyzed this database with respect to associations between
air pollution and premature mortality in Philadelphia (Samet et al., 1995, Moolgavkar et al.,

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                                    V-62a
FIGURE V-12.
             RELATIONSHIP BETWEEN RESPIRATORY HOSPITAL
             ADMISSIONS AND SULFATE CONCENTRATIONS IN
             ONTARIO (BURNETTE ET AL., 1994)
                  O 112
                   no
                  o 108
                  OT 106
                   102
                      0   2   4   6   B   10  12  M  16   l«  20
                      Daily Average Sufphote Level (yg/m*), lagged One day
         Avenge number of adjusted respiratory admissions among all 168 hospitals by decile of the daily average sulfate level
       ) lagged I day'
FIGURE V-13.     RELATIONSHIP BETWEEN RELATIVE MORTALITY AND TSP
                  OR SO2 IN PHILADELPHIA (SAMET ET AL., 1995)
                PMtdelpfcta Mortally. Tottl
                                              PMadaipMa Mortafity. Total
I-
                                           e.
                                         'I'
              »      WO       1«9         J[     0     8    40    «    «    «w

                       TSP                                   «yq

    Plots of cdimatad BonparanMtric •Sacti of TSP and SO, 
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External Review Draft                                                      £)o /yo/ Quote or Cite
November 1995                             V-63
1995, Schwartz and Dockery, 1992; Dockery, Schwartz and Pope,  1995;  Li and Roth,
1990).
       Samet et al. (1995) reanalyzed the Philadelphia dataset used by Schwartz and Dockery
(1992), covering the years of 1973 -1980,  to examine in detail the relationship between TSP
and other covariates such as weather, season, time trend variables, and SO2 in explaining
variations in daily mortality.  The authors largely confirm the findings of Schwartz and
Dockery (1992) concerning the association between TSP and  daily mortality in Philadelphia,
with important differences concerning the effects of season and the relative effects of TSP
and SO2.  In terms of concentration-response relationships, Samet et al. (1995) find some
evidence that a nonlinear, nonadditive surface of TSP and SO2 better predicts mortality than
the linear additive models used by the original investigators.  When TSP and SO2 were
considered simultaneously in an additive model but allowed to vary nonlinearly, TSP was
associated with log-relative mortality most clearly at concentrations of 100 /ig/m3 and above,
while SO2 exhibited a roughly linear increase in the log-relative mortality  rate until about 40
parts per billion, after which there was little change (Figure V-13).  The authors themselves
do not interpret the possible significance of an association with SO2 that is restricted to the
lowest concentrations.
       Drawing from the discussion of confounding in section V.D., the staff believes it
would not be plausible to interpret these results as indicating an association between SO2
acting alone and mortality.  Dockery et al.  (1995) suggest that the most parsimonious
interpretation is that both pollutants are likely serving as surrogates for the real pollutant of
concern. They  suggest fine particles are likely to be more closely associated with the
observed health effects.  Given that TSP by definition includes particles too large to be
inhaled, and, thus, is clearly an imperfect surrogate for particles of interest for respiratory
effects, it would not be surprising that other indicators such as SO2, often associated at low
concentrations with fine particles, might be better associated than TSP with observed health
effects.  Further, they suggest that if two variables are serving as proxies  for a third, local
nonlinearities, apparent interactions, or both are likely to occur.
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External Review Draft                                                     Do Not Quote or Cite
November 1995                              V-64
       Samet et al.  (1995) further examined the effects of simultaneously regressing TSP and
SO2, and found that both TSP and SO2 had independent effects, or, in models with more
extensive controls for long-term time trends, that TSP remained significant but SO2 did not
[the original findings of Schwartz and Dockery (1992)].  Furthermore, although graphs of
the concentration-response relationship for the later period, 1981-1988, are not provided,
Samet et al. (1995) report that the association between TSP and mortality is stronger over
this period than the association between SO2 and mortality.  Based on the analyses and
interpretations discussed above, to the extent that TSP can serve as a surrogate for inhalable
or fine particles that may be associated with the observed mortality effects, analyses of TSP
in Philadelphia do not appear to suggest a clear and consistent increase in mortality risk until
concentrations of approximately 100 ^g/m3 TSP.
3.     Concentration-Response Relationships from Long-Term Studies
       Several studies reporting associations between long-term (annual average) exposure to
PM and health effects, listed in Table V-20, also provide quantitative concentration-response
information showing the pattern of increased risk within the range over which increased
relative risk is reported.  Included in this list of selected studies are studies that report
associations between PM, as measured by PM25, PM15, and TSP,  and mortality and
aggravation of chronic respiratory symptoms.  These selected studies are part of the much
larger body of studies that have been evaluated in the CD and summarized in section V.C.
They  are discussed  below with regard to the nature of the concentration-response
relationships observed in the studies and the insights that can be gained with regard to the
PM concentrations where clear and consistent increases in  risk can be discerned.
       As discussed in section V.D., studies of long-term exposures are subject to different
types  of confounders and employ different means of controlling for confounding than short-
term exposure studies. In addition, the evaluation  of concentration-response relationships
                         •
specifically from studies of health effects due to long-term exposures is subject to additional
uncertainty related to  specification of relevant exposures.
       With regard to controlling for confounding  variables in long-term studies, the recent
prospective cohort studies represent a substantial advance in study design in comparison with
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                                  V-64a
           TABLE V-20. CONCENTRATION-RESPONSE INFORMATION
              FROM SELECTED LONG-TERM EXPOSURE STUDIES
Study
Concentration Range
(/ig/m3 of measured
pollutant)
Minimum Clear
Increased Risk Level
Oig/m3 of measured
pollutant)
^"^^^•-^^ss* *V >- - ^^^r^V^^tsSxv^-"*'*^ *-#^ ' ^^^^^^^^^^^^''^^^^^&:^^M^^:\
-.^""•x^3^ 1MUT "SjfjWliGfi ^ " ^ "f'»%\<*'s """"-yy "• ~~ * S f ' ^f^-f^f ffjfff v * "V1 ^ *• % -x \f -^jy^s f' ^s ^. s\, s\ j.
Mortality — 6 Cities
Dockery et al., 1993
Mortality - ACS 50 Cities
Pope et al., 1995
11 -30
9-33
15 - <30
>15
^^fM^ll^i^ i; " v, ^g-JC -^ *> ^ '^ " '>1'^^'" ^^'"^v^^^Cr^' '"X-fiT .c-^*'
-r%^M^^SM»Stufl[y<;V\ .^/* f>^ -< ** - -^ , ^ ^,- , ',, ,y^, .^ %
Bronchitis in Children — 6 Cities
Dockery et al., 1989: PM-15
PM-2.5
20-59
12-37
38
22'
TSP Study
Chronic Bronchitis — 53 Cities
Schwartz etal., 1993
48 - 130
75
'PM-2.5 concentration provided in the study for city (St. Louis), with minimum long-term concentration
showing clear and consistent risk (Figure V-16).
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             V-65
previous cross-sectional studies in that information about each subject's age, body-mass
index, lifestyle habits, etc., can be taken into account.  This improvement is important since
these studies are not restricted to one area, but rather compare relative risks in terms of
measures of air quality from different cities.  As a result, a number of risk factors that can
vary across locations are introduced by including subjects from different geographic areas,
with potentially different diets, exposures to other environmental variables, age distributions,
and other population characteristics.  Studies that involve a large number of locations or
cities (e.g., Pope et al., 1995,  Schwartz et al., 1993) or that assign individual exposure
estimates to each member of the cohort (Abbey et al., 1995a) may have a  greater likelihood
of minimizing residual confounding from unaddressed variables.
       With regard to uncertainties in specifying relevant exposures, questions arise as to the
significance and levels of air quality concentrations prior to the study period, and as to the
appropriateness of the averaging time used by the investigator. Given the  decreasing patterns
of PM concentrations observed over this century, associating risk observed in a recent study
period solely with contemporaneous air quality could serve to magnify,  on a /tg/m3 mass
basis, the apparent risk of current PM levels.  This uncertainty is addressed in the CD in
terms of the potential implications of using longer historical periods of exposure in analyzing
long-term relative risks.
       a.     PM,_« Studies
       The most significant recent studies concerning long-term effects  of  exposure to PM
are two prospective cohort studies that have directly examined the relationship between PM2 5
and mortality in cohorts of individuals across a number of U.S.  cities.  In  a study of
mortality over a 14-16 year period  involving 8,111  adults living in six U.S. cities, Dockery
et al. (1993) reported an association between the average  PM2.5 concentrations in these cities
and mortality. Concentration-response information  from this Harvard Six  City study was
provided in the form of a plot of increased risk of death by city as a function of  the annual
average PM2.5 concentration (Figure V-14).  This plot shows the relationship between PM2.5
concentrations and differences in death rates across  the cities among the cohorts after
controlling for confounders.  The observed association is highly significant (p< 0.005), with
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                                   V-65a
FIGURE V-14.
RELATIONSHIP BETWEEN MORTALITY RISK RATE RATIOS
AND PM-2.5 IN THE SIX CITY STUDY (DOCKERY ET AL.,
1993)
                    1.4 r
                    1.3
DC
to
15
                    1.1
                    1.0
                                   W
                                         H
              10   15   20
              Fine Partides
                                            25
30
                                                     35
 FIGURE V-15.
RELATIONSHIP BETWEEN ADJUSTED MORTALITY AND PM-
2.5 IN THE AMERICAN CANCER SOCDZTY STUDY (POPE ET
AL., 1995)
o 1000
o
o
o
o;
JE
o
£ 800
1 • < 1 1
1
1
.1 •
1 •
1 • ^ t
!• • ^. «f«
i • •
€ * 1*^ ** •
* , • '
H 1 - • «!
o:
O
Q 700
y,T
rr\
'. i-
' t
                 600
                                   I
                    5      10      -f      20      25      30      35
                       FINE PARTICLES (micrograms per cubic meler)

                     Age-, sex-, and race-adjusted population-based mortality rates
              for 1980 plotted against mean fine partioulate air pollution levels for 1979
              to 1983. Data from, metropolitan areas that correspond approximately to
              areas used in prospective cohort analysis.
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             V-66
apparent linearity across the cities, and the comparison of differences in death rates between
the highest and lowest cities (1.26) is in exact agreement with the relative risk from the
reported regression equation.  The clearest increased risk is observed for Steubenville, at 30
Hg/m3 long-term PM25 concentration, the only city for which statistical significance on an
individual city basis was obtained.  However, the highly significant relationship identified
across all six cities suggests that increased risk of mortality in this study is likely  to be
associated across a wider portion of the range than only for the city which  independently was
statistically significant. From this plot, it appears that a clear and consistent pattern of
increased risk is evident for the four cities with the highest annual average PM2.5
concentrations.  Of the four cities showing clear increase in risk, the lowest concentration
among these four cities is associated with Watertown, MA, which has an average
concentration of approximately 15 /ig/m3 PM2 5.
       A particular strength of this study is the long period of air quality measurements it
incorporates, and the fact that these measurements came from  monitors specifically  sited to
represent the exposure of the cohort as a whole.   For fine particles, 6 to 9  years of PM2 5
concentrations were available, beginning in  1980 (four to six years into the study), and
ending in 1985-1988 (three to seven years before the end of the study).  While it would be
ideal to have air quality monitoring extend throughout the period of study as well as
considerably before, only approximately one-fifth of the deaths had occurred in the  cohort
before fine particle monitoring had begun.  For other particle indicators evaluated in this
study, such as TSP, measurements went further back in time, but measurements of  PM2 s
extended furthest into the later years of the study, in which mortality was the greatest
(Figures 1 and 2 in Dockery et al., 1993).
       Questions remain as to whether previous  fine particle concentrations for these cities
varied substantially from concentrations monitored in  this study.  Nearly  all the cities showed
a slight decrease in fine particle concentrations over the course of the study (Figure 1 of
Dockery et al., 1993).   Assessment of historical levels of fine particles,  as indicated by
airport visibility measurements discussed in  the CD, suggests that, unlike indicators of larger
particles which may have been at dramatically higher concentrations  in several cities during
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External Review Draft                                                     DO fjO( Quote or Cite
November 1995                              V-67
the 1960s,  fine particles are likely to have been roughly equal to or only somewhat higher
than the concentrations measured during the study.  This comparison is necessarily uncertain
due to the use of airport visibility data as a surrogate for PM2J and the potential for
significant variability in long-term PM2 5 trends among cities.  Nevertheless, even if longer-
term historical concentrations are relevant for a substantial portion of the cohort, it is not
expected that inclusion of historic PM2.5 concentrations would substantially alter the nature of
the associations between PM2 5 and mortality risks seen in the study, although the impact on
quantitative study results is uncertain.
       A large-scale study by Pope et al. (1995) involving from three hundred thousand to
half a million adults living in from fifty to one hundred fifty cities nationwide also reported
associations between PM2 5 and mortality.  The ACS study sought to determine  if the
relationship between mortality and fine particles, as measured by PM2 5 and sulfates,
observed in the Harvard Six City study, could be confirmed in a larger study including ten to
thirty times the number of locations and thirty to seventy times the number of cohort
members.   The ACS study also collected detailed information on a greater number of
potential confounding risk factors than in the Harvard Six City study.
       In the ACS study the association between mortality and PM2 5 concentrations was
evaluated in fifty cities.  The PM2 5 concentration-response information from the ACS study
(Figure V-15) is based on a simple ecologic analysis, rather than a full cohort analysis,
including adjustments only for differences among cities in age, sex, and race.  In contrast,
the concentration-response assessment in the Harvard Six City study used the strength of the
prospective cohort approach, comparing PM25 concentrations against the adjusted mortality
rate for each city's cohort, with  the adjustment based on  the outcome of the control of
important risk factors on an individual basis for each individual in the cohort.  Thus, the
PM2 5 concentration-response information for mortality risk in the ACS study does not
incorporate the degree of control for confounding that the Harvard Six City study does, even
though the  full  ACS study cohort analysis incorporates control for more potential risk factors
on an individual basis than in the Harvard Six  City study.
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             V-68
       In further comparison to the Harvard Six City study, the estimates of long-term PM2.S
concentrations in the ACS study are likely to be somewhat more uncertain because the
duration of monitoring was not as long, and the monitors used had not been sited with the
population exposure of the cohort in mind.  Data from the inhalable particle network for the
period 1979-1983 was used to estimate long-term exposure of the cohort in relation to
mortality in the cohort occurring from  1982-1989.
       While recognizing these uncertainties, the ecological analysis from the ACS study
does appear to suggest that risk increases clearly and consistently at median PM2.5
concentrations above 15 jttg/m3 PM2 5.  Given the uncertainties inherent in its analyses of
concentration-response information, the ACS study, drawing from a much larger number of
cities, can be characterized as supporting the findings of Dockery et al. (1993) concerning
clear and increased  risk above 15 /ig/m3 PM2 5.
       b.    Supporting Studies With Other Indicators
       Two additional long-term studies using other indicators of PM, including PM15 and
TSP, provide concentration-response  information for associations with respiratory illness in
children  and adults.  Although these studies appear more uncertain or potentially less useful
for assessing concentration-response relationships with fine particles, they are included here
to provide information on whether the ranges of increased risk observed from the cohort
mortality studies are consistent with relevant findings from other studies of associations
between  long-term exposure and chronic morbidity.
       The effects of long-term exposures to particles on respiratory symptoms in children in
the six cities has been studied in relation to a number of PM indicators (Dockery et al.,
1989).  PM15 was observed to be statistically significantly associated with increased acute
bronchitis symptoms among the entire cohort, with PM2 5 showing the second strongest but
marginally significant association (95% CI for Odds Ratio  =  0.8 to 5.9).  When a subset of
children  with a history of asthma or persistent wheeze was analyzed separately, PM,5 and
PM25 showed consistent, marginally significant associations (CI= 0.9 - 15.5 for PM,j-, 0.9 -
13.2 for PM2.5).  This study used the same monitoring network as did Dockery et al. (1993),
which was specifically sited to measure the cohort's exposure to fine particles.  Because this
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External Review Draft                                                     Do Not Quote or Cite
November 1995                              V-69
study is restricted to children 7-11 years of age, concerns about the relevance of previous air
quality are diminished.
       Given that in five of the six cities PM2 5 comprises between 58 to 68% of the PM,5
mass, PM2 5 most likely contributes at least partially to the PM15 associations  seen with
bronchitis symptoms. Speizer (1989) suggests that the effects on bronchitis symptoms
observed in this study might be most strongly associated with acid  aerosols (H+), a
component of the fine particle fraction (Figure 3 in Speizer, 1989; Figure 12-16 in the CD).
This may be especially true for the cities with the highest particle concentrations.  However,
the one city that shows relatively large coarse particle contributions, Topeka,  has an elevated
prevalence of bronchitis as well.
       Figure V-16 shows a plot of the prevalence of bronchitis  versus PM15  concentration,
with the solid line representing those with a history of asthma or persistent wheeze.  The
cities with  the three highest concentrations, where the magnitude of increased risk is greatest,
had annual mean PMI5 concentrations ranging from 37 - 58 /xg/m3  and PM2 5  concentrations
ranging from 22 - 37 /xg/rn3, although the pattern of increased risk is not consistent across
these three cities.
       A cohort study involving information from the First National Health and Nutrition
Survey (NHANES) of 6000 adults in 53 cities adults reported associations between chronic
bronchitis and a physician-diagnosed respiratory illness and TSP  (Schwartz et al.,  1993).
Figure V-17 shows  the relative risk of chronic bronchitis versus TSP concentration, and
Figure V-18 shows  the relative risk of doctor diagnosed respiratory illness versus TSP. In
both, risk appears to be increasing clearly and consistently at the second quartile, with a
mean concentration of approximately 75 /tg/m3  TSP.
       This study is based only on the TSP concentrations from the year prior to the
NHANES assessment of effects.  To the extent  that chronic bronchitis prevalence may
involve longer exposures,  and that past TSP concentrations were potentially much higher in
some of the study area cities, these concentration-response relationships may contain
significant  uncertainty in the specification  of relevant exposures.  To the extent that TSP may
be serving  in part as a surrogate for fine particles, however, the uncertainties  in the
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                                         V-69a
FIGURE V-16.
       RELATIONSHIP BETWEEN BRONCHITIS PREVALENCE AND

       PM-15 IN THE SIX CITIES STUDY (DOCKERY ET AL., 1989).
                  50
                  40
I
o
2
o
cr
m

id
CJ
2
LU
             HI
             cr
             OL
                 30 4
                               p~l
                      10       20       30       40      50       60
              City-specific prevalence of reported bronchitis versus annual mean PM,, concentrations (wg/rn1) stratified

         by reported asthma or persistent wheeze. Upper curve 
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                                    V-69b
FIGURE V-17.
RELATIONSfflP BETWEEN RELATIVE RISK OF CHRONIC
BRONCHITIS AND TSP FOR NHANES I SURVEY SUBJECTS
(SCHWARTZ, 1993b)
                       2.0
                       1.5
                     o
                     t.
                     6
                     «»
                     o
                       1.0
                       0.5
                          40
                                 60
                                         80
                                                100
                                     120
                              ToUl Suspended P«rtioles (ug/m3)
               The relative risk of chronic bronchitis by quartiles of TSP exposure, after controlmg for age,
         race, sex, and cigarette smoking.
 FIGURE V-18.
 RELATIONSHIP BETWEEN RELATIVE RISK OF
 RESPIRATORY ILLNESS AND TSP FOR NHANES I SURVEY
 SUBJECTS (SCHWARTZ, 1993b)
                         2.0
                     £   IS
                      CL
                      V)
                      V
                         1.0
                        0.5
                           40
                                  60
                       80
                                                 100
                                      120
                               Tcttl Suspended Particles (\ig/m3)
                The relative risk of a diagnosis of respiratory illness by the examining physician by quartile
         of TSP exposure, after controlling for age, race, sex, and cigarette smoking.
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External Review Draft                                                       Do Not Quote or Cite
November 1995                              V-70

concentration-response relationships would be expected to be less, given the smaller variation

seen in historical fine particle trends.
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-1
VI.    STAFF CONCLUSIONS AND RECOMMENDATIONS ON PRIMARY NAAQS
       This chapter presents staff conclusions and recommendations for the Administrator to
consider in deciding whether to retain or revise the PM NAAQS.  Drawing from the
information and analyses discussed in Chapters IV and V, this chapter addresses the major
components needed to specify an ambient standard:  averaging time, form, pollutant
indicator,  and  level. Staff conclusions and recommendations on each of these interrelated
components are based on considering how the components of an individual standard and how
a suite of standards operate together to protect public health with an adequate margin of
safety.
       In  recommending a range of options for the Administrator to consider, the staff notes
that the final decision is largely a public health policy judgement.  A final decision must
draw upon scientific information about health effects and risks, as well as judgements about
how to deal with the range of uncertainties that are inherent in the evidence and analyses.
The staffs approach to informing these judgments is based on a recognition that the available
health effects evidence generally reflects a continuum consisting of levels at which health
effects are likely through levels at which scientists generally agree that effects may occur but
the likelihood  and magnitude of the response becomes increasingly uncertain.   This approach
is consistent with the requirements of the NAAQS provisions of the Clean Air Act and  with
how EPA and the courts have historically interpreted the Act. These provisions do not
require the Administrator to  establish a NAAQS at a zero-risk level but rather at a level that
avoids unacceptable risks and,  thus, protects public health with an adequate margin of safety.
A.     Averaging Time  and  Form of the Standards
       The current primary PM NAAQS include both a 24-hour standard with a statistical
form and an annual standard with an  arithmetic mean form.   These standards  were intended
jointly to protect the public against the health effects associated with both short-term and
long-term exposures to PM based on  epidemiological and other health studies available  at
that time.  Since the last review, numerous researchers have extended the epidemiological
database linking health effects with both short-term (from  less than 1 day to up to 5 days)
and long-term  (from generally  a year to  several years) exposures to PM. This body of
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External Review Draft                                                     Do Not Quote or Cite
November 1995                              VI-2
evidence, summarized in Chapter V, provides increased support for both short-term and
long-term standards, as discussed below.
1.     Short-term Standards
       a.    Averaging Time
       The current 24-hour averaging time is consistent with the majority of the results from
community epidemiological studies, which have reported associations of 24-hour
concentrations of PM,0, fine particles, and TSP with an array of health effects.
Nevertheless, because some such studies have found a stronger association with a multiple
day average (Pope et al., 1992; Ostro et al., 1995; Pope and Dockery et al., 1992), the staff
considered whether a multiple day averaging time would be more appropriate.   In some
geographic areas the observed health effects are associated with same day or previous day
PM concentrations.  For example, such associations are shown by mortality studies in Los
Angeles, CA; Birmingham, AL; St. Louis, MO; Toronto, Canada; Santiago, Chile; Athens,
Greece; and London, England. Further, most hospital admissions studies show associations
with same day concentrations. The 24-hour  averaging time effectively protects against
episodes lasting for several days while also protecting sensitive individuals who may
experience effects after a single day of exposure.  Thus,  the staff concludes that a longer
averaging time, such as 3 to 5 days, would not provide more effective protection  than a 24-
hour average.
       The staff has also considered the evidence regarding effects associated with PM
exposures of durations less than 24 hours;  Some investigators prior to the 1987 review
(Lawther et al., 1970) speculated that the observed health effects might be largely due to
short-term peaks on the order of an hour.  Controlled human and animal exposures to
specific components of fine particles, such as acid aerosols, also suggest  that some effects,
such as bronchoconstrictioir, can occur after exposures of minutes to hours.  Some
epidemiological studies of exposures to acid aerosols have also found changes in respiratory
symptoms in  children using averaging times less than a 24-hour period (e.g., 12 hours).
However, it is not clear whether the majority of effects that have been associated with daily
exposure to PM, including mortality and various measures of morbidity,  would occur after
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only short duration exposures.  Moreover, a 24-hour average can be expected to provide
significant protection from potential effects associated with short duration peaks in most
urban atmospheres.  Thus, although some study results may be suggestive of short duration
effects,  the staff does not believe that the reported results provide a satisfactory quantitative
basis for setting a general particle standard with an averaging time  of less than 24 hours.
Further, the staff believes that additional research is needed to examine short duration
exposures.
       Based on the above discussion, the staff recommends that consideration be given to
retaining the current 24-hour averaging time as the most appropriate to address health effects
associated with short-term (from less than 1-day to up to 5-day) exposures to PM.
       b.      Form
       As part of the  last review, the 24-hour standard was changed from a deterministic
form, in which the standard was not to be exceeded more than once per year, to a statistical
form.  The statistical form was selected to be a one-expected-exceedance  form, averaged
over 3 years.  The basis  for this change in the form of the standard was that a statistical form
can offer a more stable target for control programs and, with reasonably complete data, is
less sensitive to truly unusual meteorological conditions than the deterministic form (U.S.
EPA, 1982b).  The staff continues to believe that this rationale is sound and, thus,
recommends that consideration be given to retaining the current  statistical form for a  24-hour
PM standard.
2.     Long-term standards
       a.      Averaging Time
       As summarized in Chapter V,  community epidemiological studies  have reported
associations of annual concentrations of PM2 5, sulfates, PMIO, and TSP with an array of
health effects, notably  increased mortality  (Dockery et al., 1993, Pope et al.,  1995) and
respiratory symptoms  and illness (e.g., chronic bronchitis and cough in children).  The CD
recognizes the importance of the presence of PM in the lungs because of associated public
health concerns about both immediate and longer term symptoms produced and the long-term
potential for increased  risk of chronic lung disease. Specifically, recurrent childhood
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November 1995                              VI-4
respiratory illness has been suggested to be a risk factor for later susceptibility to lung
damage (Glezen, 1989; Samet, 1983; Gold et al., 1989) and is also increased by PM
exposure.  Therefore, serious health consequences are associated with long-term PM
exposures.
       In addition, human lung deposition data show that both coarse and fine fractions of
PM10 are able to penetrate and deposit in the gas exchange portion of the lung, an area in
which insoluble particles are retained for long periods (i.e., months to years).  Given that
particles can be retained in the lung for long periods of time, several of the plausible
mechanisms of toxicity support the need for a long-term averaging time to protect against
health effects.  Specifically, it is possible that accumulation of large lung burdens of particles
over time could be a possible mechanism or that long-term  exposures could lead to impaired
respiratory defenses.  Moreover, chemically active substances on particle surfaces, such as
acids or carcinogens, could cause damage before they are cleared, which, if not repaired,
could lead to cumulative damage.  Although the specific mechanisms of toxicity of PM
remain speculative at this time, the staff believes that information on lung deposition and
clearance provides additional support for concern with long-term PM exposures.
       The staff has also considered whether, for some effects (e.g., chronic mortality),
relevant exposure periods might better reflect the cumulative effects of PM exposures over a
number of years.  In such cases, an annual average would provide effective protection
against long-term exposures to PM that exceed  a year.  Further, the staff has considered that
air quality studies show significant seasonal variability in exposures to PM.  However,  the
staff believes that the available community studies do not support a clear association for
seasonal exposures that would be distinct from 24-hour or annual exposures.
       As discussed above,  the staff believes that an annual averaging time is consistent
with the effects observed in community epidemiological studies, as well as insights into
potential effects of long-term exposure from studies of toxicology and dosimetry.  Further,
the staff does not believe that multi-year or seasonal averaging times would be more effective
or supportable than an  annual averaging time. Thus, the staff recommends that consideration
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-5
be given to retaining the current annual averaging time as the most appropriate to address
health effects associated with long-term exposures to PM.
      b.     Form
      As part of the last review, the annual standard was changed from a geometric mean to
an arithmetic mean of the daily averages.  This change in the form of the standard was based
on an arithmetic mean being  1) more directly related to dose, which is associated with
observed health effects,  2) more sensitive to repeated short-term peaks, and 3)  more
consistent with other annual NAAQS (U.A. EPA, 1982b). The staff continues to believe that
this rationale is sound and,  thus, recommends that consideration be given to retaining the
current arithmetic average form for an annual PM standard.
B.    Particulate Matter Indicator
1.    General  Considerations
      Faced with clear evidence of adverse health effects in heavily polluted areas in the
decades after World War II, public health authorities in the U.S. and Great Britain pushed
for reductions in general particulate matter as indexed by available monitors, despite the fact
that the identity of causative agents and mechanisms was not well understood.    That these
efforts were successful is evidenced in the elimination of classical pollution episodes, greatly
improved  air quality, and reduced health risks (U.S. EPA, 1982b). As the review of U.S.
air quality trends in Chapter IV indicates, these improvements have continued under the
current PM10 standards,  in areas with differing combinations  of particulate and gaseous air
pollution.   Furthermore, concentrations of some of the more innately toxic components
(e.g., trace metals, benzo(a)pyrene (BaP)) also declined in previously polluted areas (U.S.
EPA, 1982b). Previous decisions to  control particles as  a general class, although
heterogeneous in physical and chemical composition, appear  to have been good public health
policy even though "paniculate matter"  is lexicologically undefined.   Based of the
evaluation of the updated scientific information in this review, the staff continues to believe
that separate general  PM standards (as opposed to combined  PM and SO2 standards)  remains
an appropriate policy choice for protecting public health.
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       The most recent summary of scientific information in the CD and outlined in Chapters
IV and V also continues to support past staff and CASAC recommendations regarding
selecting size specific indicators for PM standards.  More specifically, the  staff believes that
the following conclusions  reached in the 1987 assessment remain valid:
1)     Health risks posed  by inhaled particles are influenced both by the penetration and
       deposition of particles in the various regions of the respiratory tract and by the
       biological responses to these deposited materials.
2)     The risks of adverse health effects associated with deposition of ambient fine and
       coarse fraction particles in the thorax (tracheobronchial and alveolar regions of the
       respiratory tract) are markedly greater than  for deposition in  the extrathoracic (head)
       region.  Maximum particle penetration to the thoracic region occurs during oronasal
       or mouth breathing.
3)     The risks of adverse health effects from  extrathoracic deposition of general ambient
       PM are sufficiently low that particles which deposit only in that region can safely be
       excluded from the  standard indicator.
4)     The size specific indicator(s) should represent those particles capable of penetrating to
       the thoracic region, including both  the tracheobronchial and alveolar regions.
       Based upon the above considerations as well as the available  information on human
dosimetry of particles, in  the previous review the staff and CASAC  recommended a size
specific indicator that included particles less than or equal to a nominal 10  /im "cut point,"
termed PM,C. The recent  information on human particle dosimetry contained in the CD
provides no basis for changing 10 fim as the appropriate dividing line for particles capable
of penetrating to the thoracic regions.
       The large body of  new community studies  and improvements in  human exposure and
air quality presented in the CD and outlined  in Chapters  IV and V above,  however, have
significantly expanded the information regarding associations between contemporary
community air pollution containing particles and morbidity and mortality in sensitive
populations.  Even with the presence of other pollutants in the airsheds studied, PM is
independently associated with the observed health effects.  While earlier studies mainly relied
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External Review Draft                                                     Do Not Quote or Cite
November 1995                              VI-7
on BS, TSP, and sulfates as particle indicators, the recent work has added information on
PM10, fine particles, coarse fraction particles, and acid aerosols.  Because statistical
associations between these indicators and health indices have been observed at concentrations
below the current standards, the adequacy of both the indicator and the levels for the PM,0
standards have been questioned (Schwartz and Dockery, 1992a; Dockery et al., 1993;
Lippmann and Thurston, 1995).  If the constituents other than the most harmful fractions of
PMJO are captured by samplers and targeted for reduction by health protection  strategies, less
effective health protection will occur. Therefore, proper identification of the components of
PM,0 most likely responsible for the observed health effects is  critical to maximize health
protection strategies.  The indicator is used to target and monitor health protection  strategies,
and the choice is key to overall health protection provided by the PM NAAQS.  Given these
concerns and the expanded information, the staff believes it is  appropriate to reexamine the
question of whether the PM10 indicator should  undergo additional refinement to provide for
more effective protection of public health.
2.     Alternative Refinements for PM,0 Indicator
       The staff bases its conclusions and recommendations for indicator(s) on the  integration
of information in three key areas:
       •      Assessment of the totality of the evidence from epidemiology, toxicology and
              human clinical studies;
       •      Consideration of the information on dosimetry and potential mechanisms of
              toxicity; and
       •      Air quality and exposure analyses related to interpretation of the health studies.
       Key aspects  of each of  these related areas have been drawn  from  the studies contained
in the CD and summarized in Chapter V.  Based on these consideration as well as the earlier
assessment of indicators (U.S.  EPA, 1982b;  1986b), the staff has identified the following
major policy options for further refinements  to the PM10 indicator:
       •     Specifying an additional size division based on the observed bimodal ambient
             air size distribution, that is, between fine and coarse fraction particles less than
              10 fxm; and,
             Adding a chemical class indicator based on sulfates and aerosol acidity.
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       Each  of these approaches is discussed and evaluated briefly below.  The
Administrator must select the appropriate indicator(s) and consider how the indicator will
relate to providing health protection in conjunction with the other components of a standard
(i.e., averaging time, form, and level).
       a.     Indicators for the Fine and Coarse Fractions of PM^
       Recognition that ambient particle mass and volume are typically distributed bimodally
has long led to the suggestion that the health (and other) effects of the two modes should be
treated separately (NAS,  1977; Miller et al., 1979;  Wilson and Suh, 1995; Pope et al., 1995;
Schwartz et  al.,  1995).  From an atmospheric chemistry perspective, the two modes can be
thought of as separate pollutant classes with distinct properties and origins.   Although both
size fractions are implicated in  health effects, the important  differences in their physical and
chemical properties make it less clear whether the relative risk presented by the two modes
should be considered to be equivalent.  In the previous review, staff gave serious
consideration to  separating the  two classes, ultimately concluding  that the limited number of
and  nature of the community epidemiology studies available at that time could not be used to
support more than a single size specific indicator (U.S. EPA, 1982b; 1986b).
        In this review, the staff concludes that the significantly expanded community
epidemiology exposure and air  quality information provide a sufficient basis for considering
separation of fine and coarse fraction particles.  In addition,  the experience in implementing
the PMIO standards provides insights as the relative effectiveness and efficiency of standards
based  on  that indicator in limiting the risks presented by fine and coarse fraction particles.
As outlined above, staff continues to believe that both fractions of PMIO present health risks
that  must continue to be addressed  by ambient standards.  Key considerations regarding
indicators for each of these fractions are discussed below,
       i).     Fine Particles
       The staff assessment of the basis for a separate fine particle standard is summarized
as follows.
1)     The fundamental physical and chemical characteristics of the fine fraction  are
       summarized in Chapter IV.  Fine particles tend to originate  from nucleation (i.e.,
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November 1995                              VI-9
       formation of particles from low vapor pressure substances, produced either from
       combustion or from chemical reaction of gases) and condensation of gases onto
       existing particles. As a result of their physical properties, fine particles share a
       number of properties important to assessing health risk.  These include physical
       properties such as high surface area and number, a more uniform distribution in urban
       and regional scales, long atmospheric lifetimes, and increased ability to infiltrate
       indoors.  Although fine particles are chemically heterogenous, as a group they are
       generally acidic and a major fraction  is soluble and hygroscopic, while the coarse
       fraction is generally basic and insoluble.
             These differences in sources and properties also have a profound influence on
       the nature of control strategies.  Conceptually, the PM,0 indicator was intended to
       provide adequate protection from both fine and coarse fraction particles.   Areas which
       exceed the current PM  NAAQS have significant amounts of coarse fraction mass.
       Specifically, the PM10 indicator registers a substantial amount of coarse particle mass
       (e.g., up to 70 percent in the western half of the country where most exceedances  of
       the current standards occur and around 35 percent in the eastern U.S.). In practice, it
       is often easier for sources and regulators to control preferentially the locally generated
       coarse fraction. Therefore, it is not clear that a PM10 indicator, unless set at an
       unnecessarily stringent  level,  provides adequate, efficient protection from the effects
       of fine particles.
2)     Although only qualitative information exists on potential mechanisms of toxicity,
       both past and current assessments in this area suggest that the distinct physical and
       chemical properties of fine particles may contribute to enhanced risk for several
       possible mechanisms.   The enhanced effects with decreasing size in some toxicologic
       studies of laboratory generated aerosols and the substantial surface area for potential
       adsorption of irritant gases has long been noted as a reason for increased concern for
       fine particles (Natush and Wallace, 1974; U.S. EPA, 1982b; NAS, 1977a).  Although
       the relevance of the particle composition can be questioned, recent reports of the
       acute toxicity of freshly generated ultrafme particles at low concentrations show that
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November 1995                             VI-10
       severe pulmonary inflammation and death are observed in rats after brief exposures
       (Oberdorster et al.,  1995).  In this case, the large number of particles per unit mass
       may have been critical.   Preliminary work using an ambient particle concentrating
       device developed by Sioutas et al. (1995) finds lethal effects in compromised animals
       from ambient aerosol between 0.2 and 2.5 /*m at much lower concentrations than
       reported for pure compounds in other laboratory studies.
              That common physical properties (surface area and number) shared by fine
       particles in disparate areas might be instrumental in particle toxicity is also indirectly
       supported by one of the most interesting features of the recent body of epidemiologic
       literature.   As noted in Chapter V, a large number of studies conducted in cities in
       the U.S., Europe, and South America have found strikingly similar relative risks for
       particles when normalized to a comparable indicator and concentration.  Substantial
       differences are observed (or reasonably expected) in the chemical composition of fine
       and coarse fraction particles and pollutant gases  among such areas.  Although far
       from conclusive, this similarity is suggestive that some consistent  characteristic of all
       particles, such as surface area, might be involved if these associations are causal.  In
       this respect, fine particles would present a greater risk than coarse fraction particles.
             Several chemical classes of concern such as most of the acids and sulfates are
       found predominantly in the fine fraction. In general, acids are found to be more
       acutely irritating than are materials in the coarse fraction. Kleinman et al.  (1995)
       reported the relative toxicity of high concentrations of fine particle components
       (sulfate and nitrate)  in animal tests to be greater than  resuspended road dust.  Some
       transition metals and organics associated with the fine fraction have been shown to
       cause effects in lexicological experiments.  Loading particles with certain transition
       metals such as iron, vanadium, or nickel may have the potential  to enhance particle
       toxicity, acute inflammation, and non-specific bronchial responsiveness.  Adsorbed
       organic compounds  may also enhance toxicity of particles.  Diesel exhaust particles
       and gas engine particles are examples of particles whose organic extracts have been
       proven to be mutagenic and  tumorigenic in animals.
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3)     As noted above, particle deposition in the tracheobronchial and alveolar regions of the
       human lung is of greatest concern.  For quiescent breathing in normal adults, most of
       the mass of insoluble fine particles tend to penetrate to the alveolar region, where
       they may accumulate over time. Hygroscopic fine sulfates and acids, however, grow
       in the respiratory tract, resulting in significant deposition in the tracheobronchial
       region.  Furthermore, soluble particles that deposit in the alveolar region are available
       to cause damage before they are cleared, damage which if not repaired can contribute
       to cumulative effects.  Both tracheobronchial and alveolar deposition of fine particles
       may be enhanced for sensitive populations such as individuals with chronic or acute
       respiratory disease, and for small children.  Fine particles penetrate and deposit more
       efficiently in the alveolar region.
4)     Direct epidemiological evidence distinguishing the relative effects of fine versus
       coarse fraction particles is limited.  Nevertheless, a coherent body of epidemiology
       studies has shown associations of health effects with fine particles measured by PM2 5,
       BS, KM, CoH, and with classes of compounds found mostly in the fine fraction,  such
       as sulfates and associated acids. Associations with fine particles have been reported
       across the full spectrum of health effects described in  Chapter V, including mortality
       associated with short-term and long-term exposures, hospital admissions, respiratory
       symptoms, decreases in lung  function, school absences, and work absences. These
       data  alone provide a substantial basis for quantitative assessments needed to establish
       a standard level.  In addition, staff believes that the large epidemiological database
       relating to associations between health effects of short-term elevations of PM10 is best
       interpreted as primarily representing risks from fine particles, as discussed below.
       Historical pollution catastrophes such as those in London, England, in the 1950's
       were most likely caused by increases in  levels of fine  particles.
              Several recent studies have shown stronger relationships for PM2 5 than PM10
       with  both excess mortality and hospital admissions (Dockery et ah,  1993; Pope et ah,
       1995; Thurston et ah, 1994; Schwartz 1995).  Studies examining other morbidity
       endpoints reported statistically significant associations with PM,0, although the
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       associations with PM2 5 were suggestive of a trend but not statistically significant
       (Dockery et al.,  1989).  The most direct comparison of the acute effects of fine and
       coarse fraction particles is provided by the analysis of daily mortality in six cities by
       Schwartz et al., (1995).  In this analysis, both PM2J and PM,0 were  positively and
       significantly associated with fine particles, while the association with coarse particles
       was small and insignificant. While this does not show that coarse particles do not
       cause acute effects, it does indicate the mortality effects are best related to the fine
       fraction.
              Because of their physical properties, fine particles are more likely  than coarse
       particles to contribute to exposures measured  in the epidemiology studies.
       Examinations of air quality aspects of the time series PM10 mortality studies'  also
       support this suggestion:
       •     As described in Chapter IV, air quality properties of PM2 5 in the areas studied
              imply that daily  measures of PM]0 are driven  by underlying changes in PM2 5
              levels.  First, PM2 5 is  highly correlated  with PMi0 in  study locations.
              Furthermore, the day-to-day variation  of PM2 5 concentration  is predominantly
              greater than the day-to-day variation in coarse fraction concentration in these
              areas; thus, day-to-day variations in PM,0 levels are driven by variations in
              fine particle levels,  and the coarse fraction is much less variable.  Finally, in
              the Eastern U.S., where most studies were conducted, PM2 j represents a large
              fraction of the PM10 mass (63 percent of mass on average in the Eastern U.S.).
              In specific Western  U.S. cities studies, fine particles were used as
              measurements (e.g., Los Angeles, CA; Santa Clara County, CA; Denver, CO)
              or fine particles tend to dominate the PM10 measurements (e.g., woodsmoke
              communities in winter and stagnation conditions of low wind speed in
              conjunction with  combustion sources).
    'As described in the Criteria Document (Chapter 12), time series analyses attempt to use statistical
techniques to relate short-term variations in air quality measurements (o short-term variations in health endpoints
over time, typically using a 24-hour period as a unit of measure (e.g., daily PM concentrations and daily
deaths or hospital admissions) while controlling for confounding factors.
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       •      Epidemiological studies associate outdoor levels of PM to health endpoints.  In
              general, stationary monitor fine particles levels are better related to personal
              exposure measures than are coarse fraction levels.  The spatially homogeneous
              nature of fine particles means community-oriented monitors on  which most
              studies are based may better represent fine than coarse particles. Coarse
              particles are higher near sources and then levels drop off with distance from
              the source.  Thus, the community-based monitor may  not represent exposure
              to coarse particles as well as exposure to fine particles.2
                     Moreover, outdoor-origin fine particles are better able to infiltrate
              indoors in air conditioned or heated areas than are coarse particles;  once
              inside, fine particles will remain suspended for longer periods of time. Thus,
              outdoor fine particles contribute more to exposure because people spend a
              significant amount of time indoors.   It follows that time  series  associations
              between variations in particle concentrations at outdoor monitors and both
              personal exposures and  related health effects in populations that spend most of
              their time indoors are more likely due to fine particles.   The recent time
              series studies providing a direct comparison between outdoor  PM,0 and PM2.S
              and personal exposure show that both indicators are significantly related to
              variations in personal exposure, but that fine particles  show substantially
              stronger associations (Janssen et al., 1995).  By inference, the coarse fraction
              association must be smaller even than for PM,0.
                     Consequently, daily fluctuations in PM10 concentrations measured in the
              epidemiology studies are likely to  be better associated  with fluctuations in  fine
              particle concentrations.  However, insufficient monitoring data prevent this
              conclusion  ftpm being tested directly in most areas. In most  of the areas
              where the relative health significance of fine and coarse fraction particles were
       2This does not imply that the coarse fraction does not contribute to the observed health effects, only
that the time series studies would not be the most effective tool to elucidate coarse fraction associations.
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November 1995                              VI-14
            • examined directly, fine particles were more statistically significant and stable
             predictors of the health effects than coarse fraction particles.
       ii.    Coarse Fraction of PM,0
       As noted above, the staff continues to believe in the need to provide against the
potential health effects of coarse fraction particles.  Coarse fraction particles deposit in both
the tracheobronchial and alveolar region.   Long-term deposition of insoluble coarse fraction
particles in the alveolar region may have the potential for enhanced toxicity in part  because
clearance from  this region of the lung is significantly slower than from the tracheobronchial
region.
       Although none of the available community epidemiology studies has been able to
isolate high concentrations of coarse fraction particles,  occupational studies, laboratory
exposures and autopsy studies suggest a number of concerns remain about potential  risks
from the coarse fraction.  Occupational studies suggest that some effects, specifically
industrial bronchitis, may be associated with prolonged occupational exposure to coarse
particle insoluble mineral  dusts (e.g., greater than 5  £im aerodynamic diameter) (U.S. EPA,
1982b; Morgan, 1978).   Laboratory studies of potential mechanisms find that high  levels of
coarse insoluble dusts can result in responses such as bronchoconstriction, altered clearance,
and alveolar tissue damage (U.S. EPA, 1982b).  Autopsy studies of animals and humans
exposed to various ambient crustal dusts at or slightly above ambient levels typical in the
Western  U.S. suggest those exposures result in silicate pneumonoconiosis (U.S. EPA,
19825).  Responses ranged from build  up of particles in rnacrophages with no clinical
significance to possible pathological  fibrotic lesions.
       Although much of the recent  epidemiology suggests greater effects from fine particles,
it is premature  to ascribe all of the effects observed in the PMIO studies to fine particles.
This is particularly true for effects in children (Schwartz et al., 1994; Dockery et al.,  1989),
who spend more time in outdoor activity and hence receive less protection from both building
and nasal removal mechanisms.  In such studies, however, it is not possible to provide
separate estimates for coarse fraction effects levels.  3n addition, the existing ambient data
base for coarse fraction particles is quite small.  On  the other hand, the monitoring  network
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November 1995                            VI-15
for PM,0 is large,  and some of the epidemiological studies can be used to assess PM,0 levels.
If fine particle standards were established, then PM,0 would serve as a de facto indicator for
coarse fraction particles.  As noted above, in many areas, this is already the case with
respect to control strategies.  Because coarse fraction particles in such areas contribute
significantly  more mass than smaller particles, risk managers have incentives to focus
reduction measures on particle sources that contribute the most by mass.  Therefore, if a fine
particle indicator were chosen, the staff would still  recommend retention of PMIO as the
indicator to protect against the risks of coarse fraction particles.
       b.    Chemical Class Indicators — Sulfates and Acid Aerosols
       Another option for a PM indicator is a chemical class such as sulfates and acids
aerosols, metals, and organics. Each of these classes  is predominantly found in the fine
fraction.  Following the conclusion of the last PM standards review, the CASAC
recommended that special consideration be given  to only one of these classes — acid aerosols.
Accordingly, EPA prepared a comprehensive review of acid aerosols, including sulfate
aerosols  (U.S. EPA,  1989).  The review concluded that the scientific and technical basis was
not sufficient to support a separate NAAQS for acid aerosols.  The  more recent information
in the CD prompted reexamination of this issue.
       As presented in the CD and Chapter V, there are substantial  health data concerning
sulfates and acid aerosols.  This section examines their potential use as PM indicators.  Both
sulfates and acids reside almost exclusively in the fine particle fraction and  are usually
closely associated with each other.
       Sulfates have a long, well-documented history  of associations with health effects.
Some of the earliest reports of health effects from PM in the United States  used sulfate as the
air quality measurement.  Sulfates and fine particle mass are highly  correlated in many areas
of the country,  especially in the Eastern U.S.  As discussed in the CD and  Chapter  V,
epidemiology associations have been reported between sulfates and mortality and serious
morbidity endpoints such as hospital  admissions.
       Toxicological studies and human clinical studies of pH neutral or nearly neutral
sulfate salts,  however, have not been able to reproduce the  health effects observed in the
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epidemiological studies, even at relatively high concentrations (Lippmann and Thurston,
1995).  Sulfate aerosols containing strong acids such as sulfuric acid (H2SO4) do produce
functional and structural changes in healthy subjects consistent with the effects observed in
the epidemiological studies (CD, Chapter 11-13).  Consequently, although sulfate itself is not
innately of health concern, it is closely linked to acid species which have been shown in
toxicological, human clinical, and epidemiological studies to be of concern.  Based on these
factors, some investigators (Lippmann and Thurston, 1995) suggest that sulfates would be an
appropriate indicator for PM.
       A sulfate indicator would not capture all of the potential agents of concern as
effectively as a fine particle indicator.  PM associations with daily  mortality have been
observed in locations where sulfate concentrations would be expected to be low (Fairley,
1990;  Schwartz, in press (Spokane); Schwartz et al., 1993). A sulfate indicator would not
address these risks as effectively as a general fine particle standard although  a sulfate
indicator might capture some of the contributing components.  While sulfates might be a
useful proxy for acidic species in the fine fraction,  it would only include these classes.
Concern exists for the potential role of transition metals, organic compounds, ultrafine
particles, particle surface area, or number.  PM25, on the other hand, would effectively
capture all of these agents.
       Acid aerosols are currently regulated to varying degrees by  current NAAQS for PM,
sulfur dioxide,  and nitrogen oxides. Recent epidemiology studies have reported associations
between acid aerosols and health effects (See CD Table 12-3).  However, several PM
epidemiological studies in areas where acid concentrations are low or minimal have still seen
consistent particle effects (Fairley,  1990;  Pope,  1991;  Pope, 1992; Dockery et al.,  1992).
While several studies show acids to be as well or even more strongly correlated with health
effects than particle mass measurements, some other studies have found general particle
measures to be better correlated (Dockery et ah, 1992; Schwartz, et a!., 1994).
       An  acid standard would focus health protection measures on acids, leaving out control
of organics, transition metals, non-acidic  ultrafine particles, and other components of PM of
potential concern.   While fine or ultrafine acid aerosol clearly may play a role in the
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observed health effects associations, the data do not provide support for any single
mechanism or pollutant.  Therefore, using sulfates or other acid indicators would not address
these risks as effectively as a general fine particle standard.  Moreover, because sulfates
form such a large fraction of fine mass in the Eastern U.S., an appropriate fine particle
standard would focus attention on control of sulfates and associated acids.
       This review suggests that a large number of different paniculate substances  may
produce a variety of responses in animals and humans.  Identification and control of each of
the many ambient aerosol components would be difficult to accomplish, time-consuming, and
would place excessive monitoring, compliance, and other requirements on effected  agencies
and industries with no clear potential for improving public health protection over general
particulate regulation.  Given current knowledge and technical capabilities,  separate national
standards for chemical classes, including sulfates and acid aerosols, would be difficult to
support and implement, again with no obvious advantages for improving health protection
over an appropriately set fine particle standard.
3.     Staff Conclusions and Recommendations for a Particle Indicator
       Based on the  above assessments and the scientific information in the CD, the staff
draws the following conclusions:
       1)      Ambient particles  capable of penetrating to the thoracic region represent the
              greatest risk to health. Previous staff and CASAC recommendations for 10
              /im as the appropriate cut point for such particles remain valid.  The recent
              health evidence and implementation experience with PMIO have, however,
              prompted the staff to reconsider previous conclusions regarding further
              refinements to the indicator.
       2)      Any refinement of the PM10 indicator should be based on the integration of the
              totality of the evidence from epidemiology, toxicology and human clinical
              studies; consideration of respiratory tract deposition data and potential
              mechanisms of toxicity; and air quality and exposure analyses.
       3)      The staff finds that the available information is sufficient to further refine the
              indicator for the current primary standard indicator, PM10. In order to provide
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External Review Draft                                                     DO fjot Quote or Cite
November 1995                            VI-18
              more effective and efficient health protection, the staff recommends a
              distinction be made between standards for fine particle and for coarse fraction
              particles.
       4)     Movement to chemical class indicators is not advisable during this review.  Of
              the paniculate chemical classes, most is known about sulfates and acids.  In
              the past reviews, staff has concluded that insufficient data exist to set a
              separate national sulfate or acid aerosol standard  (U.S. EPA 1989; 1986b;
              1982b).  The staff continues to concur with these judgments.  Additional
              components of fine particles have also been demonstrated to be of health
              concern. Because sulfates form such a large fraction of fine mass in many
              areas, an appropriate fine particle indicator would result in control of sulfate-
              related species.
       Based on these conclusions, the  staff makes the following recommendations with
respect to reviewing the adequacy of the current indicator for PM:
       1)     The PM,0 indicator should be retained.  PM10 is the most  appropriate surrogate
              for additional protection from potential risks of coarse fraction particles. A
              separate coarse particle indicator is not appropriate because of the much  larger
              data base associated with PMI0.
       2)     A fine particle indicator should also be added to provide more effective
              protection against the  risk posed by fine particles.
       As discussed  in Chapter IV and Appendix A, the minimum particle diameter between
the fine and coarse modes lies between  1 and 3 j*m, and the scientific data support a cut
point to delineate fine particles in this range.  Because of the potential overlap of fine and
coarse particle mass  in this intermodal region, specific cut points are only an approximation
of fine particles.  Thus, the decision within this range is largely a policy judgement.  Based
on considerations of consistency with health data, the limited  potential  for intrusion of coarse
particles into the fine fraction, and availability of monitoring  technology, the staff
recommends  using a PM2.5 gravimetric measurement, which will be further specified in the
Federal Reference Method and equivalency program.
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External Review Draft                                                    Do Not Quote or Cite
November 1995                            VI-19
       From a public health perspective, PM2.5 captures all of the potential agents of concern
in the fine fraction.  For example, PM2 5 captures most sulfates, acids, fine particle metals,
organics, and ultrafine particles and accounts for most of surface area, and particle number.
PM2.5 has been used directly in many health studies as described in the CD and Chapter V.
PM2.s has some potential for intrusion of particles generated by grinding or crushing (i.e.,
coarse mode particles) into the daily PM2 s measurement.  A sharper inlet for the Federal
Reference Method may help to minimize the intrusion of coarse mode particles into the PM2 5
measurement.  Although intrusion of coarse mode particles into daily PM2 5 measurements is
not anticipated to be significant in most situations, if subsequent data reveal problems in  this
regard, this issue might be better addressed on a case-by-case basis in the monitoring and
implementation programs.  Furthermore, PM2 s measurement technologies are widely
available and have been in use since the 1970s.
       PM,, on the other hand, has not been used in health studies primarily due to lack of
available monitoring data.  PM, could reduce possible intrusion of coarse mode particles in
some situations, but it might not capture all of the fine mode in other situations.  PM,
sampling technologies have been developed; however, the PM, samplers have not been
widely field-tested to date. Thus, the staff recommends the use of PM2^ as the fine particle
indicator.
C.     Level of the Standards
       Selecting a suite of PM ambient air quality standards that provide an adequate margin
of safety remains a difficult challenge for the decision maker despite recent new studies and
analyses since the last review that provide significant relevant information and insights.
Although we can now somewhat better characterize PM, it remains a pollutant class with
chemical and physical characteristics that vary with  geographic location, source mix,
meteorology, and time. Tijis aspect of PM inherently makes interpretation of
epidemiological evidence difficult and diminishes the utility of controlled human and animal
studies in making quantitative judgments about appropriate ranges of standard levels.  In
addressing  this issue, the staff recognizes, as in past reviews, that although the scientific
literature supports the notion that various mixes of particles pose risks to health, the basis for
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External Review Draft                                                      Do Not Quote or Cite
November 1995                             VI-20
any general PM standards is largely a public health policy judgment.  The staff believes that
by considering policy alternatives that focus control on those particles with the greatest
potential for causing health  effects of concern, primarily through PM2.5 standards as
recommended above, a more effective and efficient policy response would result than that
associated with the current suite of standards.
1.     General Considerations and Approach
       In developing an approach to formulating recommendations on appropriate ranges of
standard levels, the staff has taken into account the following considerations:
       1)     Recent new epidemiological studies are noteworthy in their scope and efforts
              to account for potential confounding and other uncertainties (e.g.,
              characterization  of exposure). However, each individual study has inherent
              and methodological limitations and interpretation of these findings is the
              subject of ongoing debate within  the scientific community. Thus, the staff
              views its assessment of each  individual study in  the context of the overall body
              of epidemiological evidence (with mechanistic support from lexicological and
              dosimetry studies) and the consistency and coherence of results across studies
              and effects.
       2)     As noted in the  last review, it continues to be the case that even  the best
              epidemiological  studies can do no more than observe site-, time-, and monitor-
              specific associations between levels of a given pollutant and health responses.
              Further, such studies  cannot be expected to provide clear evidence of
              population thresholds of response. Thus, the staff recognizes that attempting
              to identify "lowest observed effects levels" and adding margins of safety
              below such levels is not an appropriate approach in this case.  Instead, the
              staff has attempted to assess the nature of health risks, and the associated
              uncertainties, along a continuum of exposures using the full range of available
              health and exposure data from the specific key and supporting studies.
       3)     Relative to other single pollutants for which NAAQS  have been  set,
              establishing appropriate ranges of levels for  general PM standards involves
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External Review Draft                                                      Do Not Quote or Cite
November 1995                             VI-21
             unusually large uncertainties.  While recent studies help to reduce the
             uncertainties that were present in the last review, they do not change this basic
             observation relative to other NAAQS.  To better address these uncertainties
             over time, the staff believes that research should continue into the more
             difficult problem of identifying and assessing potential health effects that may
             be associated with specific chemical and physical characteristics  within the
             mixture of particles.  However, even without any additional chemical-specific
             evidence, the staff believes that the large uncertainties inherent in setting
             general PM standards do not preclude our identifying appropriate ranges of
             policy alternatives from which specific PM standards can be selected to
             effectively and efficiently protect public  health with an adequate margin of
             safety.
       Taking these considerations into account, the staffs approach to formulating
recommendations on appropriate ranges of standard levels for the recommended indicators
and averaging times is based on:  1) staff assessments of the quantitative concentration-
response relationships suggested by  specific epidemiological studies identified in the CD as
appropriate for quantitative assessment purposes; 2) consideration of how these studies may
be applied in developing ranges specifically for PM2 5 and PM,0 standards; and 3) qualitative
consideration of the uncertainties and other key factors that affect the margins of safety
associated with ranges of standard levels.  This approach recognizes that final decisions about
appropriate PM standard levels must draw not only on  scientific information about  health
effects and risks, but also on policy judgments about when observed effects become adverse
from a public health perspective and how to deal with the range of uncertainties that are
inherent in the evidence and assessments.
       These staff assessments and considerations are discussed below for both 24-hour and
annual PM2 5 standards, as well as for PM,0 standards.  The following discussions are based
on information  in the  CD and in Chapters IV and V of this Staff Paper.
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 External Review Draft                                                     Do Not Quote or Cite
 November 1995                              VI-22
 2.     Specific Considerations and Conclusions for PM25 Standards
        a.    24-Hour PM? < Standard
        i.     Levels of Interest from Short-term Epidemiological Studies
        As discussed in section V.E, selected epidemiological studies provide quantitative
 concentration-response information useful in developing an appropriate range of standard
 levels for consideration in setting a new 24-hour PM2.5 standard.  In the last PM standards
 review, studies were not available that directly used the PM,0 indicator that was established
 based on that review.  In this review, by contrast, several studies are available that directly
 use the currently recommended PM25 indicator (Schwartz et al.,  in press; Dockery et al.,
 1992; Schwartz et al.,  1994).  A larger number of studies using PMIO, as well  as reanalyses
 of some datasets by independent reviewers,  are also now available to provide concentration-
 response information (Pope et al., 1992; Schwartz, 1993a, 1994g; Schwartz et  al., 1994e;
 Schwartz, 1994d; Schwartz and Morris, in press; Pope and  Dockery, 1992; Samet et al.,
 1995).  These key PM25 and PM10 studies are supported by other studies that used sulfates
 and TSP as indicators of exposure (Burnette et al., 1994, 1995; Samet et al., 1995). These
 selected studies were the basis for staffs assessment to discern concentrations of the
 measured pollutants at which risk increases in a clear and consistent pattern in these studies,
 as presented in Table V-19.
        To gain insight into the coherence of these short-term studies with regard to estimated
 24-hour PM2 5 concentrations at which clear and consistent increases in risk may occur, staff
 converted all such estimates  in terms of the measured pollutants into estimates of PM25,
 shown in Table VI-1. In so doing, staff is aware that this approach is premised on assuming
 that PM2 5 concentration-response relationships for these studies would be similar to those
 observed  for other  measured particle indicators.  Further, staff recognizes that translating
 exposures measured in terms of one particle indicator to PM2 5 exposures incorporates
additional uncertainties beyond those inherent in specifying exposures directly in terms of a
measured particle indicator.  To minimize this uncertainty to the extent possible, site-specific
conversion factors were used wherever available. Taking  into account these caveats, staff
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                                           VI-22a
    TABLE VI-1.  ESTIMATED LEVELS OF MINIMUM CLEAR INCREASED RISK
       IN TERMS OF MEASURED OR ESTIMATED PM2^ (24-HOUR AVERAGE)
Study/PM Indicator
MORTALITY - 6 Cities - PM-2.5
Schwartz et al., in press
MORTALITY - St. Louis - PM-2.5/PM-10
Dockery etal., 1992
Sametetal., 1995
MORTALITY - Utah Valley - PM-10
Pope et al., 1992
Samet et al., 1995
MORTALITY - Birmingham - PM-10
Schwartz, 1993a, 1994g
Samet et al., 1995
MORTALITY - Philadelphia TSP
Samet et al., 1995
HOSPITAL ADMISSIONS - Birmingham - PM-10
Schwartz etal., 1994e
HOSPITAL ADMISSIONS - Detroit - PM-10
Schwartz, 1994d
HOSPITAL ADMISSIONS (Cardiac) - Detroit - PM-10
Schwartz and Morris, in press
HOSPITAL ADMISSIONS - Ontario - Sulfate
Burnetteetal., 1994, 1995
RESPIRATORY SYMPTOMS - 6 Cities - PM-2.5
Schwartz etal., 1994
RESPIRATORY SYMPTOMS - Utah Valley - PM-10
Pope and Dockery, 1992
Minimum Clear Increased Risk
Level for PM^
(/ig/m3 of measured or
estimated PMU)
<30
21'
28'
272
292
343
303
344
11 -263
335
23s
13 - 18*
<;187
322
'Concentration to PM-2.5 from PM-10 quartile done by using a site-specific PM-2.5/PM-10 ratio for the period
 of study (0.64).
Inversion to PM-2.5 used nationwide PM-2.5/PMT10 ratio for all seasons (0.58) from SAI, 1995, because
 urbanized Utah Valley judged not well represented by other Southwest sites.
3Minimum clear risks indicates lowest concentration on nonparametric smoothed curve where a clear and
 consistent increase in risk is evident.  Conversion to PM-2.5 done using the PM-2.5/PM-10 ratio for Southeast
 region from SAI, 1995 (0.57).
^Conversion to PM-2.5 done by applying median PM-2.5/TSP ratio available for 1982 in Philadelphia (0.34),
 using data from the inhalable particle network.
'Conversion to PM-2.5 done using PM-2.5/PM-10 ratio (0.63) for central U.S. from SAI, 1995.
*Conversion to PM-2.5 done using site-specific regression equations to convert from sulfate to PM-10 for the
 three major cities in the study and converting the PM-10 values to PM-2.5 using a nationwide PM-2.5/PM-10
 regression equation for Canada (CEPA/FPAC Working Group, 1995; Brook et al., in press).  The results agree
 closely with those obtained using a  sulfate/PM-2.5 ratio for Toronto from Thurston et al., 1994.
'Conversion to PM-2.5 from PM-10 done by using site-specific ratio for the period of study (0.6).
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-23
believes that this approach provides useful insight beyond that which can be obtained by only
looking at each study independently.
       As seen in Table VI-1, the selected short-term PM25 and PMIO studies most useful for
evaluating quantitative concentration-response relationships appear to show strong coherence
in terms of measured and estimated PM2 5 concentrations at which the  risk of observed
mortality and morbidity effects appears to clearly and consistently increase.  From the
mortality studies, risk appears to clearly and consistently increase at PM2 5 concentrations
somewhat below 30 ^g/m3.  The morbidity studies show a wider range of estimates  for
concentrations of clear and consistent risk, ranging from somewhat below 20 /xg/m3  to
somewhat above 30 ftg/m3.  When the sulfate and TSP studies are considered as surrogates
for PM2 5, these studies yield estimates of PM2 5 concentrations where risk increases  in a
clear and consistent pattern that are within the range of that seen  in the PM2 5 and PM10
studies.  Thus, this staff assessment suggests that, when considered together, the short-term
epidemiological studies are quantitatively coherent and support the judgment  that evidence of
increased mortality and morbidity risks become more apparent when daily  PM2,
concentrations reach approximately  20 jcg/m3 to somewhat below 30 /*g/m3.
       The above discussion of 24-hour PM2 5 levels at which increased risks of various
health effects are likely is based on  interpreting the quantitative study results as  being
primarily attributable to changes in  PM2 5 levels. The staff believes such an interpretation is
reasonable in light of the entire body of evidence and given efforts in the  original studies and
reanalyses to control for  potential confounding and to characterize exposures in  terms of
PM2 5 concentrations in selected studies where such information was available.   However, the
staff recognizes that various issues have been raised that call into question  using these study
results directly as a basis for establishing a range of levels for a 24-hour PM2 s standard.
Alternative interpretations of the studies, for example, raise the possibility that the observed
effects may  in part be more appropriately attributed to specific components within the
mixture of PM or to other pollutants in the mixture of ambient air in general, despite
extensive efforts to control for such confounders. Further, limitations on  matching exposures
of the population subgroup experiencing effects to the ambient measurements of PM, and the
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-24
conversions of measured concentrations of other indicators into PM2.5 concentrations that
have been used in developing exposure-response relationships for PM2 s call into question the
specific levels at which effects are likely to be experienced.  Finally, the degree of
prematurity of death observed in the mortality studies is an issue in regard to the extent to
which such prematurity — if it is, for example, on the order of a few days — should be
considered a matter of public health concern.
       These issues are discussed further below. Taking into account all such questions,
however, the staff considers it appropriate at a minimum to interpret the short-term
quantitative studies as a body of evidence that, when taken together with information from
controlled human and animal studies, supports the following conclusion: adverse public
health effects, including premature mortality and increased morbidity, are likely to occur in
various sensitive population subgroups  at 24-hour PM2 5 concentrations below those that
occur when the current 24-hour PM,0 NAAQS is attained.  Thus, the staff concludes that a
PM2.5 concentration that is approximately equivalent to 150 jtg/m3 PM10 represents a clear
level of concern where health effects can with confidence be  attributed to PM exposures.
This approximately equivalent PM2 s concentration varies from about 55 to about 95 /zg/m3
for western regions and eastern regions, respectively, across the U.S., with the national
average conversion yielding a 24-hour  PM2 5 level of about 85 ftg/m3 as the approximate
equivalent of the current 24-hour PM10 NAAQS. Setting a 24-hour PM2 5 standard  at this
level would give maximum weight to the issues and uncertainties mentioned above by, in
essence,  completely discounting the quantitative study results, and no weight to the coherence
of the entire body of evidence that has  become available since the last review of the PM
standards.  Such a standard could not be construed  as being at all precautionary in nature,
nor to provide any identifiable margin of safety. Instead, the staff believes that the issues
and uncertainties mentioned above should be considered in the context of deciding what
standard within the range recommended below will, in the Administrator's judgment, provide
an adequate margin of safety.
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External Review Draft                                                      Do Not Quote or Cite
November 1995                             VI-25
       ii.     Margin of Safety Considerations for a 24-Hour PM2 5 Standard
       As discussed above, there are a number of issues that the staff believes are relevant
and appropriate to consider in deciding what standard  will provide and adequate margin of
safety.
       An effect of rtair pollution" on mortality is now broadly accepted by the scientific
community (Moolgavkar, 1995, Samet et al., 1995), but differing views remain as to the
degree to which the risk of premature mortality can be quantitatively associated with PM.
Further, associations between air pollutants other than PM have been well-established for
some of the morbidity effects linked to PM, resulting  in uncertainties in the degree to which
the risk of observed morbidity effects can be quantitatively associated  with PM.  As
discussed in section V.D, when the health effects of PM are evaluated across the entire body
of evidence, not  just looking at each  study independently,  concerns are lessened by the
absence of consistent and plausible confounding by other candidate pollutant(s).  Further,
investigations into plausible mechanisms, elucidating how exposure to ambient levels of PM
may result in the observed effects have not  yet established definite pathways from exposure
to effects at ambient PM concentrations.  Therefore, substantial uncertainty will remain
concerning the agent(s) responsible for the observed associations.
       A related uncertainty concerns the degree to which effects associated with PM can be
attributed primarily to the fine particle fraction of PM. Although the existing health
literature contains more studies using PM10  as a general indicator of particles than it does
studies of PM2 s, the staff concludes that the existing PM2 5 studies strongly implicate fine
particles, and as  discussed in Chapter V,  that much of the larger body of PM10 studies can be
interpreted as linking effects to the fine particle component of PM,0.  Further, there are
differing views as to the degree to which specific chemical classes within PM2.5 may be
primarily associated with observed effects.  The staff believes this issue concerning  specific
chemical classes  should be considered in judging the desirability of a more general surrogate
indicator (i.e.,  one that is likely to include the various physical  properties and chemical
constituents causally linked to effects) as a practical guide  to the development of effective
and efficient control strategies.
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-26
       Another relevant factor concerns the uncertainties associated with using fixed-point
outdoor monitoring networks, and area-wide conversions between a measured indicator and
estimates for another indicator of PM exposure, to specify exposures in quantitative analyses
of exposure-response relationships.  Although recent studies have become more sophisticated
in the application of central, fixed-site monitoring to community-wide measures of health
effects, significant uncertainties necessarily remain.  As discussed in Chapter IV, the
importance of this uncertainty is lessened for fine particles, which have good serial
correlation between central  monitors and personal exposure (Janssen et al., 1995), are
generally more uniformly distributed across a community than other PM indicators, and
penetrate more efficiently indoors where much of individual exposures to PM occur.
       Uncertainties in specifying exposures carry over into analyses of the exposure-
response relationships directed toward gaining insight into patterns of increasing  risk over
relevant PM concentration ranges.  The staff has attempted to minimize the impact of such
uncertainties concerning concentration-response by evaluating available information from
individual studies to attempt to discern  where the clearest and most consistent patterns of
increased risk are evident, and, further, to consider the coherence of these analyses in the
context of the entire body of evidence.
       Another factor to be addressed in margin of safety considerations includes the
uncertainties and differing views with regard to the degree of life shortening that is reflected
in the mortality events associated with short-term PM exposure. The extent of life
shortening  in these studies is difficult to specify, with some authors reporting  that  at least a
portion of the mortality effects from short-term exposures may involve little displacement of
mortality (Spix et al., 1993). Other findings from short-term exposure studies (Pope  et al.,
1992) and from long-term exposure studies (Dockery et al., 1993; Pope et al., 1995)  suggest
that substantial displacement of mortality may be occurring in some cases.  The staff believes
that assessing the public health significance of this effect ultimately involves a general policy
judgment that should be made in the context of considering what standard will provide an
adequate margin of safety.
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-27
       b.     Annual PM2 5 Standard
       i.      Levels of Interest from Long-term Epidemiological Studies
       Staff has used the same approach to identify concentration levels of interest for an
annual PM2.5 standard as described above for a 24-hour PM2 5 standard. Although only four
long-term studies were judged to provide quantitative concentration-response information
useful in developing an appropriate range of consideration for an annual PM2.5 standard, two
of these studies directly examined the effects of PM2.5 exposure on mortality (Dockery et al.,
1995; Pope et al.,  1993). These PM2J mortality studies are supported by studies of
morbidity effects (e.g., chronic bronchitis in children and adults) using PM,5  and TSP
(Dockery et al., 1989;  Schwartz et al., 1993). These selected studies were the basis for
staffs assessment to discern concentrations of the measured pollutants at which risk increases
in a clear and consistent pattern in these studies, as presented in  Table V-20.
       To gain insight into the coherence of these long-term studies with regard  to estimated
annual PM2 5 concentrations at which clear and consistent increases in risk may occur, staff
converted all such estimates in terms of the measured pollutants  into estimates of PM2 5,
shown in Table VI-2.  In so doing, staff is aware that this approach is premised  on assuming
that PM2 5 concentration-response patterns  would be similar to those observed for other
measured particle  indicators.  Further, staff recognizes  that translating exposures measured in
terms of one particle indicator to PM2 5 exposures incorporates additional uncertainties
beyond those inherent in  specifying exposures directly in terms of a  measured particle
indicator. Taking inlo account these caveats, staff believes that this  approach  provides  useful
insight beyond  that which can be obtained by only looking at each study independently.
       The two strongest studies of the effects of long-term exposures to PM2 5 are the
Harvard Six  City (Dockery  et al., 1993) and ACS (Pope et al., 1995) mortality studies.  As
seen in Table VI-2, the Harvard Six City study suggests a range of clear and consistent risk
of from 15 ^g/m3 to below 30 /xg/m3 PM25.  Available  concentration-response information
from the ACS study, which  examined cities with a similar range of long-term particle
concentrations to the Harvard Six City study, provides evidence of clear risk at
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                                      VI-27a

   TABLE VI-2.  ESTIMATED LEVELS OF MINIMUM CLEAR INCREASED RISK
      IN TERMS OF MEASURED OR ESTIMATED PM^ (ANNUAL AVERAGE)
Study/PM Indicator
MORTALITY - 6 Cities - PM-2.5
Dockery et al., 1993
MORTALITY - ACS 50 Cities - PM-2.5
Pope et al., 1995
BRONCHITIS IN CHILDREN - 6 Cities - PM-2.5/PM-10
Dockery et al., 1989
CHRONIC BRONCHITIS - 53 Cities - TSP
Schwartz etal., 1993
Minimum Clear Increased Risk
Level for PM^j
(/ig/m3 of measured or estimated
PMW)
15 - <30
>15
22
23'
'Derived from applying conversion factors for PM-10/TSP (0.5) and PM-2.5/PM-10 (0.6) for late 1970's -
early 1980's data and previous as given in the 1986 SPA (pgs. 8 & 11) (U.S. EPA, 1986b.)  Ratios may have
differed somewhat over the study period (1970-1974).
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-28
concentrations above 15 Mg/rn3 PM2S.  Thus, the ACS study provides support that effects
may be occurring at the lower end of the Harvard Six City study range.
       The findings of these mortality studies,  which associate PM2 5 with mortality of
sufficient prematurity to give rise to differences in overall annualized mortality rates, lessens
the likelihood that mortality events associated with PM2 5 solely involve only very brief
shortening of life.  Further, the ability to look across regions  of substantially different PM
composition  allows for more confident focus on PM2 5 as being primarily responsible for the
observed effects  (Dockery et al.,  1993).  Staff notes that questions raised in the CD about the
appropriate exposure period to use in examining long-term mortality effects add to the
uncertainty in interpreting the magnitude of risk and the concentration at which risk increases
in a clear and consistent pattern suggested by these studies. Staff believes  that these
important uncertainties dealing with mortality effects should be addressed as part of the
margin of safety considerations.
       Coherence between the mortality and morbidity studies is more difficult to judge
because the morbidity effects can be less confidently ascribed primarily to  PM2 5 and require
uncertain conversions from other PM indicators to arrive at estimates of PM2.5. However,
when expressed in terms  of PM2 5, the morbidity studies suggest estimates  of minimum PM2 5
concentrations of clear and consistent risk from 22 to 23 /xg/m3.  These morbidity studies
support the judgment that clear and consistent risk from  long-term exposures to PM2 5 is
likely to occur well  below 30 jtg/m3 annual average PM2 5.
       ii.     Margin of Safety Considerations for an Annual PM2 5 Standard
       Staff has  identified several factors that are relevant and appropriate  to consider in
assessing margin of safety considerations, as discussed below.
       Similar to the short-term studies, uncertainties in  attributing observed effects
specifically to PM, rather than to other co-pollutants, and more specifically to PM2 s, are an
important factor  in margin of safety considerations.  Several long-term studies have found
PM to be a stronger indicator for many health effects from long-term exposures than other
potentially confounding pollutants (Abbey et al., 1995c;  Dockery et al.,  1993;  Dockery et
al., 1989), as well as PM25 being an equal or better indicator  than other measures of PM
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External Review Draft                                                     Do Not Quote or Cite
November 1995                              VI-29
(Dockery et al., 1993; Abbey et ah, 1995c). However, as long as mechanistic investigations
have not established definite pathways from exposure to effects, uncertainty will remain
concerning the agent(s) responsible for the observed effects.  Further, uncertainties about
specific causal  agents should be addressed in considering the desirability of a more general
surrogate indicator; i.e., one that is likely to include the various physical properties and
chemical constituents causally linked to effects, as a practical guide to the development of
effective and efficient control strategies.
       With regard to specifying exposures, long-term studies have the  same uncertainties as
do short-term studies concerning the use of centrally-located, fixed-site  monitors, generally
compounded by the comparison across different urban areas. The current long-term
mortality and morbidity cohort studies address this problem by controlling other potential
confounding risk factors.  Some also site monitors with a goal of characterizing the study
population exposure (Dockery et al., 1989;  1993) or use fixed monitoring information broken
down on a subject-by-subject basis (Abbey et al., 1991;  1993).  However,  uncertainties with
regard to specification of exposures necessarily remain for long-term studies.
       An  important uncertainty involves whether cumulative effects from a long period  of
exposure to PM pollution,  not fully captured in the monitoring done for a study,  might be
most relevant for some of the observed health effects.  If a large proportion of subjects were
responding to cumulative exposures over a period of years, and the air quality concentrations
prior to the studies were substantially higher than during the studies, this circumstance could
lead to an overestimate of the effects of PM on health.  Examination of historical visibility
records suggests that historical levels of fine particles do not appear to be substantially higher
than that used in a key  mortality study (Dockery et al., 1993).  Further, some morbidity
studies addressed this question by either testing the effects of particle concentrations several
years previous  to the effecjt (Abbey et  al., 1995b) or by restricting their study population to
young children (Dockery et al.,  1989).  In general, however, the current lack of knowledge
concerning the  most relevant exposure periods for the effects associated with long-term
exposure to PM suggests that exposure estimates for long-term studies incorporate greater
uncertainty than those from short-term studies.
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External Review Draft                                                     DO f^ot Quote or Cite
November 1995                             VI-30
       Another factor to be considered is the uncertainty relating to the degree to which the
long-term studies are detecting additional increased risk of chronic mortality or other
endpoints, or are just  measuring the cumulative impact of associations with short-term
exposures.  Given uncertainties concerning the measure of exposures, both current and
historical, for the long-term studies, as well as corresponding uncertainties in the short-term
exposure studies, a comparative assessment of the magnitude of risk observed by both study
approaches is difficult.  However, any mortality resulting from short-term exposures that is
substantially premature should be reflected in the mortality events measured in long-term
studies.  Thus,  the long-term studies can be interpreted as indicating either that a significant
portion of the mortality associated with short-term exposures involves significant prematurity,
or, more likely, that the mortality associated with long-term exposures includes both chronic
and acute mortality effects.
3.     Staff Recommendations for PM2 5 Standards
       The following staff recommendations  are based most directly on the above discussion,
but take into account the entire body of evidence presented  in the CD and in Chapter V.
These recommendations suggest ranges of levels for 24-hour and annual PM2 5 standards that
the staff believes would protect against the various adverse  health effects associated with
exposures to PM that have been reported in a large number of epidemiological studies and
supported by evidence from  controlled human and animal studies.
       a.     24-Hour PM, 5 Standard
       With regard to a 24-hour PM2 5 standard,  the staff offers the following
reco m mendation s:
       1)     The upper end of the range of consideration for a new 24-hour PM25 standard
              should be below the PM2 5 concentration that  is approximately equivalent to the
              level of protection provided by the current PM,0 standard.  An approximately
              equivalent 24-hour PM2 5 concentration, about 85 jig/m3 on average in the
              U.S., contains no identifiable margin of safety and should not be considered as
              an appropriate standard  alternative  While the uncertainties inherent in the
              most recent  epidemiological studies are important  margin of safety
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-31
             considerations, the staff believes there is no basis for discounting the
             quantitative results from these studies completely in selecting an upper end of
             range of consideration.  Thus, staff recommends that weight be given to the
             coherence of the entire body of epidemiological evidence, with support from
             controlled human and animal studies, in limiting consideration to a level below
             85 fig/in* for a new 24-hour PM2 5 standard.
       2)    The lower end of the range of consideration for a new 24-hour PM2.S standard
             be 25 fig/m3. The key and supporting epidemiological studies relied upon to
             assess the point at which increased risks of adverse health effects can be
             clearly seen, taken together, suggest a range of levels from somewhat below
             20 /xg/m3 to somewhat over 30 /xg/m3.   In considering a 24-hour PM2.S level of
             25 jig/m3 as the lower end of the range, the staff places  significant weight on
             the coherence of the study results,  even  in light of inherent uncertainties and
             alternative interpretations possible for each study considered independently.
             The staff believes that a 24-hour PM2 5 standard set at this level would be
             precautionary in nature in protecting against a full range of short-term effects
             associated with the identified sensitive subgroups of the population, giving less
             weight to concerns that the relied-upon studies may not have completely
             controlled for all potential confounding variables nor fully accounted for all
             limitations in the exposure data.
       3)    In selecting a level for a 24-hour PM2 5  standard within this range,  the
             Administrator should consider the degree and nature of protection that will be
             afforded by a new annual PM2 5 standard.  The joint protection provided by a
             suite of standards that includes both 24-hour and annual  PM2 5 standards should
             be considered in selecting the levels for each standard.  One possible policy
             approach would be to view an annual PM2 5 standard as serving as the primary
             driving force for control programs that would effectively lower the entire
             distribution of PM2 5 concentrations,  thus serving to protect not only against
             long-term effects but also short-term effects as well.  With this approach,  the
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-32
             24-hour PM2.5 standard would be set so as to protect against the occurrence of
             peak 24-hour concentrations that would likely not be controlled by areas
             attaining a new annual PM2.5 standard. Thus, in conjunction with an annual
             PM2 5 standard, the Administrator may judge that the 24-hour standard should
             be set so as to limit only those peak 24-hour concentrations that are likely to
             persist upon attainment of the annual standard.  The comparative air quality
             data presented in Chapter IV (Table IV-8) shows approximately 90% of the
             monitored PM25 annual-peak-to-mean ratios below 3.34 on average  nationwide
             (with a range from 3.1 in the southeast to 3.8 in the northwest).  Thus,
             considering the joint protection afforded by both 24-hour and annual standards
             suggests,  for example, that a 24-hour PM2 5 level of about  65 /tg/m3 might be
             an appropriate complement to a 20 ftg/m3 annual PM2 5 standard.
       b.     Annual PM2 5 Standard
       With regard to an annual PM2 5 standard, staff offers the following recommendations:
       1)     Staff recommends that the upper end of the range of consideration for a new
             annual PM2 5 standard should be below 30 ^g/m3.  This level, which is
             approximately equivalent on average across the U.S. to the level of the current
             annual PM10, contains no identifiable margin of safety and  should  not be
             considered as an appropriate standard alternative.  While the uncertainties
             inherent in the most recent  epidemiological  studies are important margin  of
             safety considerations, staff believes there is no basis for discounting  the
             quantitative results from these studies completely in selecting an upper end of
             range of consideration.  Thus, the staff recommends that weight be given to
             the coherence of the entire body of long-term epidemiological evidence, with
             mechanistic support from controlled human and  animal studies, in  limiting
             consideration to a  level below 30 /*g/m3 for a new annual PM2 5 standard.
      2)     Staff recommends that the lower end of the range of consideration for a new
             annual PM2 5 standard be 15 ^g/m3.   A standard set at this  level would place
             greater weight on the full range of exposure-response relationships from the
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External Review Draft                                                     Do Not Quote or Cite
November 1995                            VI-33
              key mortality studies and on the staffs assessment of the levels at which
              mortality risk clearly increases. In recommending this lower level of
              consideration, staff recognizes that this level does not represent a threshold
              below which there is no risk of premature mortality.  Rather, the staff judges
              that below this level the uncertainties in historical air quality and relevant
              periods of exposure, as well as potential confounding by other environmental
              and/or personal lifestyle factors, become sufficiently great as to serve as an
              appropriate bound for a policy choice intended to avoid unacceptable risk.
       3)     The staff recommends that in selecting  a level for an annual PM2 5  standard
              within this range, the Administrator consider the degree and nature of
              protection that will be afforded by a new 24-hour PM2 5 standard.  The joint
              protection provided by a suite of standards that includes both 24-hour and
              annual PM2 5 standards should be considered in selecting the levels for each
              standard.
4.     Staff Conclusions and Recommendations  for PMi0 Standards
       The following staff conclusions and recommendations are based on a reexamination of
the previous conclusions regarding PM10 standards in  light of the above recommendations
regarding fine particle standards and the body of evidence presented in the CD  and  Chapters
IV and V of this paper.  The staff makes the following conclusions and recommendations
regarding PM10 standards:
       1)     Assuming a fine particle standard  is established, the major function of the
              PM10 standard is to protect against the known and anticipated effects  associated
              with coarse fraction particles in the size range of 2.5 to 10 /*m.  It is difficult
              to discern the incremental effects of coarse fraction particles from fine
              particles in available community epidemiology studies.
       2)     Based on the assessment of the available studies, the staff finds that the best
              evidence for drawing quantitative  conclusions for PM10 comes  from a long-
              term cohort study of acute bronchitis in children in the Harvard Six City study
              (Dockery et al.,  1989).  This study found somewhat better associations with
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-34
              PM15 than with PM2 5 over the entire cohort.   This suggests that coarse
              fraction particles, in combination with fine particles, may have influenced the
              observed effects.  From a mechanistic perspective, it is possible that prolonged
              deposition of coarse fraction particles could be elevated in children, who are
              more prone to be active outdoors than adults.  Moreover, the major site of
              thoracic deposition, the tracheobronchial region, would be expected to be the
              region  involved in the effects. It is of note that Dockery et al. (1989) is an
              update  of the study by Ware et al.,  (1986), which formed the main basis for
              the level of the current annual PM10 standard.  The staff concludes there is no
              basis in the more recent study to alter the level and form of current annual
              PM10 standard, which is 50 fig/m3, annual arithmetic mean.
       3)     The staff also considered other potential effects of annual coarse particle
              exposures that were not evaluated in community epidemiology studies. These
              include altered clearance, industrial  bronchitis, and alveolar tissue damage;
              such effects have been reported at levels much above those that would be
              permitted under the standard.  At levels nearer, but likely above the level of
              the standard,  autopsy  studies found  silicate pneumoconiosis associated with
              particles  that  by analyses were consistent with exposure to crustal materials.
              While these findings support retention of the current PM10 standard, they
              provide no basis for changing the level.
       4)     The level of the current 24-hour PM]0 standard (150 /xg/m3) was based in large
              measure on the London mortality and morbidity studies.  As noted above, the
              present assessment of the more numerous recent short-term studies has led to
              the staff conclusion that such effects are far more likely to be associated with
              fine particles.  Accordingly, the staff recommends that these effects should be
              addressed with a fine particle standard.
       5)     Available community  studies conducted in areas with elevated coarse fraction
              concentrations suggest that short-term effects occur at concentrations well
              above the current standard. Johnson et al., (1992)  found  that an episode of
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External Review Draft                                                     Do Not Quote or Cite
November 1995                            VI-35
              very high concentrations of volcanic ash had little effect on pulmonary
              function in a panel of school children.  Hefflin et al., (1994) studied hospital
              admissions in an agricultural community in eastern Washington.  Short-term
              exposures to PM,0 were associated with increased respiratory effects across the
              year, which included both fine and coarse exposures. During a two week
              period in which two windblown dust episodes occurred  with particle levels
              exceeding 1,000 /ig/m3, only hospital admissions for upper respiratory
              infections showed an increase of even marginal significance.  The authors
              conclude that dust in the community has only a small effect on general
              respiratory health.
       6)     Based on the lack of clear evidence for short-term effects  of coarse fraction
              particles at or near the level of the current PM10 standard, the staff examined
              the relative protection afforded by the annual standard.  Based on the  typical
              24 hour to annual ratios in Chapter IV, the annual standard would be  expected
              to provide substantial protection against the occurrence of high coarse fraction
              concentrations.  Using the average ratio of 3 (Table  IV-6), an annual  average
              of 50 Atg/m3 would have a daily maximum of 150 jig/m3 or less. In areas with
              more variability, the ratios can be larger, but are still likely to limit the peak
              concentrations of coarse fraction particles from human derived activities to
              levels below those expected to be associated  with adverse  health effects.
              Using the data from Table IV-7, 95% of areas with  an annual mean of 50
              /tg/m3 would have 24-hour maxima below 250 /tg/m3.
       7)     In summary, the staff recommends retention  of the current annual PM10
              standard of 50 /xg/m3, annual arithmetic mean. This standard is judged to
              provide adequate protection against the  long-term and short-term effects
              associated with the presence of coarse fraction particles.
D.     Summary of Staff Recommendations
       The major staff conclusions and recommendations made in sections VI.A-C above are
briefly summarized below:
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External Review Draft                                                     Do Not Quote or Cite
November 1995                              VI-36
       1)     General PM standards remain a reasonable public health policy choice.
       2)     While the current PM10 standards provide protection from both fine and coarse
              mode particles that are capable of penetrating to the most sensitive regions of
              the  human respiratory tract,  the tracheobronchial and alveolar regions, the staff
              concludes that the fine fraction of PM|0 is more likely to contain those physical
              and chemical properties and  components associated most  strongly with a broad
              array of adverse public health effects, including premature mortality as well as
              various measures of increased morbidity in children and other  sensitive
              populations.  Further, retaining PMIO as the sole indicator of PM would
              continue to direct control efforts towards coarse fraction particles, which
              available evidence suggests are of lower risk to health than the fine  fraction.
              Thus, a new fine particle indicator is recommended, to include those particles
              with an aerodynamic diameter less than a nominal 2.5 ^m, in addition to
              retention of a PM10 indicator to continue to limit coarse mode particle
              pollution.
       3)     Staff recommends replacing  the current 24-hour PM10 standard with a new 24-
              hour PM25 standard, with a  statistical expected  exceedance form,  and
              supplementing the current annual  PM10 standard with a new annual PM2 5
              standard, with an arithmetic  average form. This suite of indicators  and
              averaging times is judged to be sufficient to address all the components of PM
              that have been associated with adverse health effects.
       4)     Based on the staffs assessment of the short-term epidemioiogical data, the
              range of 24-hour PM2 5 levels of interest is 25 to less than 85 jig/m3.  Given
              the  coherence of the body of short-term epidemioiogical evidence for increased
              risk in  areas where the current standard is attained and the seriousness of the
              potential health effects, the upper end of the above range is judged to  represent
              a clear level of concern with  no identifiable margin of safety and should not be
              considered as an appropriate standard alternative.  Although some degree of
              increased risk to public health below 25 «g/m3 cannot be excluded,
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VI-37
             consideration of the entire body of epidemiological and controlled human and
             animal studies do not suggest increased health risks of consequence below this
             level. The uncertainties inherent in the epidemiological evidence, in particular
             with regard to potential confounding by other environmental factors,
             limitations on quantifying exposures, and differing judgments as to the public
             health significance of the degree of prematurity of death observed in the
             mortality studies, should be considered in evaluating margins of safety
             associated with alternative 24-hour PM2 5 standards in the range of 25 /xg/m3 to
             somewhat below 85 jtg/m3.
       5)    Based on the staffs assessment of the long-term epidemiological data,  the
             range of annual average PM2.5  levels of interest is 15 to less than 30 ^cg/m3.
             Given the recent large-scale studies directly associating long-term PM2.5
             exposure with  premature mortality, the supporting evidence from other chronic
             morbidity studies, and the seriousness of the potential health effects, the upper
             end of the above range is judged to represent a clear level of concern with no
             identifiable margin of safety and should not be considered as an appropriate
             standard alternative.  Although some degree of increased  risk to public health
             below 15 jig/m3 cannot be excluded, when uncertainties in historical exposures
             and relevant exposure periods are considered, the epidemiological evidence
             does not suggest increased risk of consequence below this level.  The
             uncertainties inherent in the epidemiological evidence, in  particular with regard
             to potential confounding by other environmental and personal/lifestyle factors
             and limitations on quantifying exposures, should be considered in evaluating
             margins of safety associated with alternative annual PM2 5 standards in the
             range of 15 /*g/m3 to somewhat below 30 ftg/m3.
       6)    When selecting final PM2 5 standard levels, consideration  should be given to
             the joint protection afforded by the 24-hour and annual standards taken
             together.  For example, an annual PM2 5 standard at 20 /xg/m3 would be
             expected to result in substantially reduced 24-hour levels, potentially limiting
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November 1995                             VI-38
              maximum 24-hour levels to less than about 65 /ig/m3 in approximately 90%  of
              the areas, thus adding to the protection against short-term effects afforded by a
              24-hour standard.
       7)     Based on staff assessments of air quality, lexicological, and epidemiological
              evidence available since the last review, retention of the current annual PM10
              standard is recommended to provide ongoing control of coarse mode particles
              for protection against known and anticipated adverse health effects associated
              with both 24-hour and annual exposures.
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External Review Draft                                                   Do Not Quote or Cite
November 1995                            VII-1
VH.   CRITICAL ELEMENTS IN THE REVIEW OF THE SECONDARY STANDARD
       FOR PARTICULATE MATTER
A.     Introduction
       This chapter presents critical information for the review of the secondary NAAQS for
particulate matter drawing upon  the most relevant information contained in the CD.  The
welfare effects of most concern  for this review are visibility impairment, soiling, damage to
man-made materials,  and damage to and deterioration of property.  For each category of
effects,  the chapter presents (1)  a brief summary of the relevant scientific information and (2)
a staff assessment of whether the available information suggests consideration of secondary
standards different than the recommended primary standards.  Staff conclusions  and
recommendations related to the secondary standard for PM are presented at the  end of the
chapter.
       The chapter does not address in detail the effects of particles on climate  change. As
discussed in the criteria document, particles (in  the submicrometer size range) can result in
perturbations of the radiation field that are generally expressed as radiative forcing.
Radiative forcing due to aerosols has a cooling effect on climate through the reflection of
solar energy. This is in contrast to "greenhouse gas" that produces a positive long wave
radiative forcing which has a warming effect. Given the complex interaction of these two
phenomena and the present state of the science,  it is the staffs judgment that these effects
should not be addressed in this paper, but should instead be considered in the broader context
of global climate change.
B.     Effects of PM on Visibility
1.     Types of Visibility Impairment
       Visibility effects are manifested in two principal ways:  (1) as local impairment (e.g.,
plumes and localized hazes) and (2) as regional  haze.  Local-scale impairment is defined as
impairment that is "reasonably attributable" to a single source or group of sources.  This
type of impairment is considered to be an effect primarily due to nearby sources, although it
can be part of a larger, regional impairment.  Visibility impairment in some urban areas can
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External Review Draft                                                      Do Not Quote or Cite
November 1995                              VTI-2
be dominated by local rather than regional sources, depending on site-specific geographical
and meteorological factors.
       The second category of impairment,  regional haze, is produced from  a  multitude of
sources and impairs visibility in every direction over a large area, such as an urban area, or
possibly over several states. Objects on the horizon are masked and the contrast of nearby
objects is reduced.  In some cases, the haze may be elevated and appear as layers of
discoloration.  Multiple sources may combine over many days to produce haze, which is
often regional in scale.  The fate of regional haze is a function of meteorological and
chemical processes, sometimes causing fine particle loadings to remain suspended in the
atmosphere for long periods of time and to be transported long distances  from their sources.
2.     Social Valuation of Visibility
       Visibility is an air quality-related value essential to people's enjoyment  of daily
activities in all parts of the country.  Survey research on public awareness of visual air
quality using direct questioning typically reveals that 80% or more of the respondents are
aware of poor  visual air quality (Cohen et al., 1986).  Individuals value good visibility for
the well-being  it provides them directly, both in the places where they live and work, and in
the places  where they enjoy recreational opportunities.  Thousands of Americans appreciate
the scenic  vistas in national parks and wilderness areas  annually.  Visibility is also highly
valued, however, because of the importance people place on protecting nationally significant
natural areas, both now and in the future.  Many individuals want to protect such areas for
the benefit of future generations, even if they personally do not visit these areas very
frequently (Chestnut et al., 1994).  Society also values visibility because of the significant
role it plays in air transportation.  Serious episodes of visibility impairment can lead to
increased risks in the air transportation industry,  particularly in urban areas with high traffic
levels (U.S. EPA, 19825).
       Many contingent valuation studies have been performed in an attempt to quantify
benefits (or individuals' willingness to pay)  associated with  improvements in current visibility
conditions.  The results of  several studies are presented in table VII-1.  As an  example of the
potential value attributable  to improvements in visibility, a recent study estimates visibility
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                            VII-2a
         Table VII-1.   Comparison of  Residential Visibility
                        Valuation Study Results
Study
Eastern CVM Studies
McCleUand et al.5


Tolley et al.4


TolleyetaP


ToUey ctal6


Tolley et al*


Tolley et al6


ToUeyetal6


Tolley et a?


Rae7
California CVM
Studies
Brooksirc et al.'


Lochman et ar

California Property
Value Sutdy

Trijonis et aln

Trijonis et al'°
Chy

Atlanta and
Chicago

Chicago


Atlanta


Boston


Mobile


Washington, DC


Cincinnati


Miami


Cincinnati


Los Angeles


San Francisco


•

Los Angeles

San Francisco
MeanWTP
($1990)

Unadj. $39
Partial $25
Full $18
-$318
$305
$379
-$265
$255
$381
-$196
$187
$231
-$212
$227
$266
-$314
$323
$410
-$78
$77
$86
4134
$120
$141
$175


$115
$294
$161
-$186
$109






Suiting VR
(miles)

17.6


9
9
9
12
12
12
18
18
18
10
10
10
15
15
15
9
9
9
13
13
13
11.4


2
2
12
18.6
16.3






Ending VR
(miles)

20


4
18
30
7
22
32
13
28
38
5
20
30
10
25
35
4
19
29
8
19
29
16.4


12
28
28
16.3
18.6






b
coefficient

305
196
140
367


414


372


275


560


106


226


531 '


105


1172







WTPfor
20% changes
VR(3)

$56
$36
$26
$67


$75


$68


$68


$102


$17


$41


$97


$19


$214



$216-$579

$437-$487

Note: VR - Visual Range
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External Review Draft                                                      TJO yvbr Quote or Cite
November 1995                             VH-3
benefits due  to reduced sulfur dioxide emissions under the acid rain program to be quite
significant, in the range of $1.7 - 2.5 billion annually by the year 2010 (Chestnut et al.,
1994).
3.     Visibility-Impairing Particles
       Visibility impairment has been considered the "best understood and most easily
measured effect of air pollution" (Council on Environmental Quality, 1978). It is perhaps
the most noticeable effect of fine particles (i.e., those with an  aerodynamic diameter less than
2.5 /*m) present in the atmosphere.  Fine particles  are effective in impairing visibility
because the mean diameter of fine particles is usually less than or only slightly greater than
the wavelength range of visible light, and light scattering is at a maximum when  the
wavelength is comparable to the particle diameter.  Fine particles in the size range from 0.1
to 1.0 nm in diameter are more effective per unit mass concentration at impairing visibility
than either larger or smaller particles (NAPAP, 1991).
       Air pollution degrades the visual appearance of distant  objects to an observer, and
reduces the range at which they can be distinguished from the background.  Particles affect
color of distant objects depending upon particle size, composition, scattering angle between
observer and illumination, and optical characteristics of the background target.
       Fine particles,  which can be emitted directly to the atmosphere through  primary
emissions or formed secondarily from gaseous precursors, impair visibility by scattering or
absorbing light.  Different types of particles have varying efficiencies in causing visibility
impairment.
       The fine particles (and associated  paniculate water)  principally responsible for
visibility impairment are sulfates, nitrates, organic matter, elemental carbon (soot), and soil
dust.  Coarse particles (i.e., those in the  2.5 to 10 ^m size range) also impair visibility,
although less efficiently than fine particles.  Sulfates and nitrates readily absorb water from
the atmosphere and grow in  size in a nonlinear fashion as relative humidity levels increase.
Soluble organics are considered to be less hygroscopic than sulfates and nitrates (Sisler,
1993).  All of these particles scatter  light.  Light absorption is caused  mainly by  elemental
carbon.
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VII-4
       Sulfates, nitrates, and some organic particles begin as gaseous emissions and undergo
chemical transformation in the atmosphere.  These fine particles and their precursors can
remain in the atmosphere for several days and can be carried hundreds or even thousands of
kilometers from their sources to remote locations, such as national parks and wilderness
areas (NRC, 1993).
4.     Metrics for Expressing Visibility Impairment and Light Extinction.
       Daytime visibility is determined the competition between transmitted radiance and
path radiance.  Transmitted radiance comes from the object being viewed and contains all of
the information about that object available to the observer.   Path radiance is scattered by the
atmosphere into the line of sight, and contains no information about the object being viewed.
When path radiance dominates transmitted radiance, as in a dense fog, visibility is poor.
Path radiance is used in models  that calculate visibility as a function of particle
concentration, composition, and size.
       Light extinction is an optical property of each point in the atmosphere and is closely
linked to air quality.  In itself, light extinction is not the best indicator of visibility for a
specific scene.  However, light extinction is a useful measure of haze because it represents
the effect that gases and aerosols have on changes in path radiance.  Therefore,  light
extinction is a useful indicator of visibility for regulatory purposes.
       The light extinction coefficient can be defined as the fraction of light lost or
redirected per unit distance through interactions with gases and suspended particles in the
atmosphere.  This coefficient is  typically expressed  in  terms of inverse kilometers or
megameters (km'1 or Mm"1).  Direct relationships exist between the concentrations of particle
types and their contributions to the extinction coefficient. By apportioning the extinction
coefficient to different particle types,  one can estimate changes in visibility due to changes in
constituent concentrations (Pitchford and Malm, 1994).
       The extinction coefficient is inversely related to visual range.  Conversion from light
extinction coefficient to visual range can be done with the following equation:  Standard
visual range (in kilometers) = 3.912 / light extinction coefficient (in M'^CNAPAP, 1991).
Visual range can be defined as the maximum distance  (i.e., miles or kilometers) at which one
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External Review Draft                                                      £)o Not Quote or Cite
November 1995                             VII-5
can identify an object against a uniform background.  Visual range has been widely used in
air transportation and military operations  in addition to its use in characterizing air quality.
Because it is expressed in familiar units and has a straightforward definition, visual range is
likely to continue as a popular measure of atmospheric visibility (Pitchford and Malm, 1994).
       Another important visibility metric is the deciview, which measures perceived
haziness. It is designed to be linear with respect to perceived visual changes over its entire
range in a way that is analogous to the decibel scale for sound (Pitchford and Malm,  1994).
Neither visual range nor the extinction coefficient has this property.  For example, a 5 km
change in visual range or 0.01 km"1 change in extinction coefficient can result in a change
that  is either imperceptible or very apparent depending on baseline visibility conditions.
Deciview allows  one to more effectively express perceptible changes in visibility, regardless
of baseline conditions.  A one deciview change is a small but perceptible scenic change under
many conditions, approximately equal to a 10% change in the extinction coefficient.  The
deciview metric may be useful for defining perceptible changes in future regulatory
programs.  Figure VII-1 illustrates the relationships between these three visibility metrics.
5.     Overview of Current Visibility Conditions
       Visibility  conditions vary regionally,  as a function of background levels of fine
particles, average relative humidity levels, and generally higher anthropogenic particle
loadings in the East as opposed to the West.  An overview of current visibility conditions,
developed from monitored aerosol concentrations and  expressed in terms of the light
extinction coefficient, is provided in figure VII-2 (Sisler et ai., 1993).  Median standard
visual range in the rural mountain and desert, areas of the Southwest average 130-190 km,
whereas median visual range in the rural  areas south of the Great Lakes and east  of the
Mississippi River is between  20 and 35 km.
       Most of this six-fold difference between East and West is due to greater sulfate
concentrations in the East and the effect of higher humidity levels in the East (NAPAP,
1991).  Studies of historical  visibility trends have shown a fairly strong correlation between
long-term light extinction levels and sulfur dioxide emissions.  Figure VII-3 illustrates this
correlation for the southeastern  U.S.
-------
                             VII-5a
  1.6 T,
                                Extinction Coefficient

                             • ' Visual Range
                             20    25    30

                              Haziness (dv)
Figure  VII-1.  Visual range and extinction coefficient as  a
                function of  haziness expressed in deciview.
-------
                               VII-5b
                 (a). Total light extinction b^ (Mm"1)
          (b). Extinction due to coarse particles and fine soil (Mm"1)


Figure VII-2. Average reconstructed  light extinction coefficient
(Mm'1) calculated  from the aerosol concentrations  measured during
the first three years of IMPROVE, March  1988 through February
1991.  The various  panels of this figure show total  extinction
(including Rayleigh scattering due to air) and  the contributions
due to the various  aerosol components: coarse particles and
soil, sulfate, organic carbon, nitrate, and light-absorbing
carbon.
-------
                   03
                   
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VII-6
       The following sections further explain the reasons for regional variability in visibility
impairment.
6.     Estimated Background Levels of Fine Particles and Associated Light Extinction
       Total light extinction is determined by the combined effects of fine particles from
background (i.e., natural) sources, Rayleigh scattering, and fine particles from anthropogenic
sources. The 1990 National  Acid Precipitation Assessment Program report estimated annual
average background levels of fine particles by particle type, and related contributions to light
extinction, expressed in inverse megameters (Mnr1) (NAPAP,  1991). Table VII-2, shows
that background fine particle concentrations are estimated at 3.32 ^g/m3  in the East and 1.47
jtg/m3 in the West.
       The contribution of each particle type to total light extinction is derived by
multiplying the estimated average concentration by the extinction efficiency for that particle
type.  Extinction efficiencies used in table VII-2 are for "dry" particles only.  Associated
water is expressed as a separate particle type.
       Other studies have used slightly different extinction efficiencies for dry particles than
those found in table VII-2. For example,  Sisler et al. (1993) used the dry extinction
efficiencies in table VII-3 in  an analysis of monitoring data collected from the Interagency
Monitoring of Protected  Visual Environments (IMPROVE) visibility monitoring network,  a
cooperative program in place since 1986 involving several Federal agencies and State
representatives.
7.     Role of Humidity in Light Extinction
       As mentioned previously, humidity plays a significant role in the  impairment of
visibility by fine particles, particularly in the East, where annual  average relative humidity
levels are 70-80% as compared to 50-60% in the West (Sisler et  al., 1993).  Two ways that
the effect of humidity on light extinction can be represented are by including water as a
separate particle type (as is done in table VII-2), or by multiplying particle-specific extinction
efficiencies by correction factors representing  ]) the hygroscopic nature of the particle, and
2) the average annual humidity for the relevant location (Sisler et al., 1993).
-------
                                               VII-6a

                                             Table  VII-2

                 Average  Natural  Background  Levels  of  Aerosols
                                     and  Light Extinction
Average Concentration

FINE PARTICLES (<2.5 urn)
Sulfates (as NH4 HSO4)
Organics
Elemental Carbon
Ammonium Nitrate
Soil Dust
Water
East
fig/m3
0.2
1.5
0.02
0.1
0.5
1.0
West
Jig/m3
0.1
0.5
0.02
0.1
0.5
0.25
Error
Factor
2
2
2-3
2
1 '/2 -2
2
Extinction
Efficiencies*
m2/g
2.5
3.75
10.5
2.5
1.25
5
Extinction Contributions
East
Mm'1
0.5
5.6
0.2
0.2
0.6
5.0
West
Mm'1
0.2
1.9
0.2
0.2
0.6
1.2
COARSE PARTICLES (2.5-10 \im)
                           3.0
3.0
0.6
1.8
1.8
                                                       RAYLEIGH SCATTER

                                                                   TOTAL
                                               12

                                               26 ±7
                              11

                              1712.5
'The extinction efficiencies are based on the literature review by Trijonis ct al. (19S6 & 1988). All the extinction efficiencies represent
 particle scattering, except for elemental carbon where the 10.5 m2/g value is assumed to consist of 9 m2/g absorption and 1.5 m2/g
 scattering. Note that the 0.6 m2/g value for coarse particles is a "pseudo-coarse scattering efficiency" representing the total scattering by
 all ambient coarse particles (< 2.5 Jim) divided by the coarse particle mass between 2.5 and 10 ujn.
-------
                          VII-6b
Particle
Type
sulfates
organics
elemental carbon
nitrates
soil dust
coarse particles
Extinction
Efficiency
(in m2/g)
3.0
3.0
10.0
3.0
1.0
0.6
                       Source: Sisler et al. 1993
Table VII-3.  Dry particle light extinction efficiency values used in 1993
analysis of IMPROVE data.
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VH-7
       Because annual average relative humidity is higher in the East, the same ambient
concentration of sulfate, for example, will on average lead to greater light extinction in an
eastern location rather than a western one.  The top map in figure VII-4 illustrates the
regional variability of annual mean relative  humidity nationwide.  The bottom map depicts
the variability of the relative humidity correction  factor used for sulfates in the IMPROVE
analysis (Sisler et al., 1993).  For example, when corrected for humidity, the overall
extinction efficiency for sulfates in the East may exceed 11-12 m2/g, whereas the extinction
efficiency for sulfate in the West may be one-third to one-half of that.
8.     Rayleigh Scattering
       Table VII-2  shows the contribution to total light extinction from "Rayleigh scatter."
Rayleigh scattering  represents the degree of light extinction found in a particle-free
atmosphere, caused by the gas molecules that make up "blue sky" (e.g., N2, 02, CO2 )(U.S.
EPA, 1979). Rayleigh scattering thus can be used to establish a maximum horizontal visual
range in the earth's atmosphere,  absent visibility-impairing particles. At  sea level, this
maximum visual range is approximately 326 kilometers (equivalent to light extinction of 12
Mm"1).  While Rayleigh scattering can be shown to establish this maximum visual range, it
should not be considered to contribute to visibility impairment. Rather, only fine and coarse
particles from natural and anthropogenic sources should be considered responsible for
impairing visibility  (from the maximum visual range "baseline" established by Rayleigh
scattering).
       Estimated extinction contributions from Rayleigh scattering and  background levels of
fine and coarse particles, in the absence of anthropogenic emissions of visibility-impairing
particles, are estimated to result in a visual  range in the East of 150+/- 45 kilometers and
230 +/- 40 km in the West. NAPAP (1991) estimated that the major contributors to
nonanthropogenic light extinction levels in the East are Rayleigh scattering (46%), organics
(22%), water (19%), and suspended dust, including coarse particles (9%).  The major
contributors in the West are Rayleigh scattering (64%), suspended dust (14%), organics
(11%), and water (7%).  Thus, higher levels of background fine particles in the East result
in a fairly significant difference between maximum visual range estimates in the East and West.
-------
              JU*	90
                                     VII-7a
                                (a) Annual mean relative humidity.
                                          3-84.2
Figure  VII-4,
                   (b)  F^

Spatial variation  in average relative humidity (NOAA,  1978)  and the
sulfate RH correction factor Fr
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External Review Draft                                                     Do Not Quote or Cite
November 1995                             VII-8
9.     Significance of Anthropogenic Sources of Fine Particles
       The concentrations of background fine particles are generally small when compared
with concentrations of fine particles from anthropogenic sources.  The same relationship
holds true when one compares light extinction due to background fine particles with light
extinction due to anthropogenic fine particles.  Man-made contributions account for about
one-third of the average extinction coefficient in the rural West and more than 80% in the
rural East (NAPAP, 1991).
       This fact is well-documented by data from the IMPROVE visibility monitoring
network (Sisler et al., 1993). Table VH-4 compares total light extinction (from background
and anthropogenic sources) with light extinction due only to natural sources for. several
locations across the country.  The table demonstrates the significant role in most parts of the
country of anthropogenic emissions  in overall light extinction as compared to background
fine  particle levels.
       It should be noted that even in  those areas with relatively low concentrations of
anthropogenic fine particles, such as the Colorado plateau, small increases in anthropogenic
fine  particle concentrations can lead to significant decreases in visual range.  National
concern with protecting visibility in the highly valued national parks and wilderness areas in
this region led to the inclusion of specific language in section 169B of the 1990 Clean Air
Act Amendments, requiring EPA to form the Grand Canyon Visibility Transport
Commission.  The Commission is required to provide the Administrator with
recommendations for protecting regional visibility in the future.
10.    Regional Differences in Anthropogenic Pollutant Levels
       While total light extinction levels vary significantly across the country, so does the
mix  of visibility-impairing pollutants from region to region. Table VII-5, taken from the
1993 National Academy of.Sciences (NAS) study on visibility, shows the estimated
contribution of various anthropogenic pollutants to visibility impairment for three main
regions  of the  U.S. The table takes into account relative emissions levels of each pollutant
type within each region.  This and other analyses (Sisler et al., 1993) show that sulfates are a
significant cause of visibility impairment in all parts of the country, but particularly in the
-------
                                       VII-8a
REGION

Eastern U.S., estimated
natural light extinction
Appalachian
Boundary Waters
Northeast
Washington, D.C.
Western U.S., estimated
natural light extinction
Colorado Plateau
Cascades
Southern California
Northern Rockies
TOTAL LIGHT
EXTINCTION, 1988-
1991
(in Mm'1)
Annual
26 +/- 7
112
68
71
164
17 +/- 2.5
27
59
63
54
Summer
NA
193
73
88
192
NA
29
68
76
46
VISUAL
RANGE
(in km)
Annual
150 +/- 45
35
58
55
24
230 +/-40
145
66
62
72
Summer
NA
20
54
44
20
NA
135
58
51
85
                                                  bource:  Sisler a al. 1993
Table VII-4.  Comparison of total light extinction to estimated natural light extinction for
several eastern and western  locations.
-------
                             VII-8b


                           Table VII-5

         Visibility Model Results:  Anthropogenic Light
                        Extinction Budgets"
                    East"      Southwest0     Northwest1
Sulfates
Organics
Elemental carbon
Suspended dust
Nitrates
Nitrogen dioxide
65
14
11
2
5
3
39
18
14
15
9
5
33
28
15
7
13
4
"Percentage  contribution by specific pollutant to anthropogenic
 light extinction in three regions of the United States.

bBased  on Table 9,  Table 18,  Figure 45,  Appendix A,  and Appendix
E of NAPAP Visibility SOS/T Report  (Trijonis et al., 1990). It is
assumed that sulfates (3% natural) account for 60% of non-
Rayleigh extinction, organics  (33% natural) account for 18%,
elemental carbon (3% natural) accounts for 10%, suspended dust
(50% natural) accounts  for 4%, nitrates  (10% natural) account for
5%, and nitrogen dioxide  (10% natural) accounts for 3%.

'Based  on Table 9,  Table 18,  Figure 45,  Appendix A,  and Appendix
E of the NAPAP Visibility SOS/T Report  (Trijonis et al., 1990).
It is assumed that sulfates  (10% natural) account for 33% of non-
Rayleigh extinction, organics  (33% natural) account for 20%,
elemental carbon (10% natural) accounts  for 12%, suspended dust
(50% natural) accounts  for 23%, nitrates (105 natural) account
for 8%, and nitrogen dioxide  (10% natural) accounts for 4%.

dExtinction  efficiencies (relative to organics are chosen as 1.5
for sulfates, 2.5 for elemental carbon,  0.3 for fine crustal
materials, and 1.5 for  nitrates (Trijonis et al., 1988, 1990).
Coarse dust extinction  is assumed to be  three times fine dust
extinction (Trijonis et al., 1988, 1990).  Natural aerosol
particle fractions are  assumed to be one-tenth for sulfates, one-
third for organics one-tenth for elemental carbon, one-half for
crustal materials,  and  one-tenth for nitrates.  These assumptions
are applied using the fine mass concentrations in Trijonis et
al., (1990).  The percentage contribution for nitrogen dioxide  is
assumed to be 4%.
-------
External Revie\v Draft                                                      Do Not Quote or Cite
November 1995                             VII-9
East, where they are responsible for about two-thirds of overall light extinction.  In the
Southwest and Northwest, organics play a larger role, as does elemental carbon.  Suspended
dust is also a major constituent in the  southwest.  The main source categories responsible for
visibility-impairing fine particle and precursor emissions are listed in table VII-6 (NAS,
1993).
11.    Regional Variation in Urban Visibility
       Visibility impairment has been studied  in several major cities in the past decade (e.g.
Middleton, 1993) because of concerns about fine  particles and their potentially significant
impacts (e.g., aesthetic and health-related) on  the many residents of large metropolitan areas.
Urban areas  generally have higher loadings of fine paniculate matter than monitored class I
areas, and they demonstrate significant variability in the degree to which different pollutant
types contribute to overall light extinction.  Table VII-7 illustrates annual average and
second-highest maximum fine PM levels for various cities in the  U.S.
       Table VII-8 illustrates the difference between percentage contributions of particle
types to annual average total light extinction in the Washington, DC urban area and the
southern California areas. The dominance of sulfate in Washington, DC exhibits a regional
effect stemming from  sulfur dioxide emissions outside the metropolitan area.  In contrast,
nitrate plays  the greatest role in the  overall light extinction levels in the mountainous areas
just outside Los Angeles, with most of the nitrate formation in this area coming from
nitrogen dioxide  emissions within the urban area.
12.    Staff  Considerations Pertaining to the Effects of PM on Visibility
       Impairment of visibility in multi-state regions, urban areas,  and class I areas (i.e.,
certain national parks, wilderness areas, and international parks as described in section
162(a) of the Act) is clearly an adverse effect  on  public welfare.  The  staff has considered a
number of factors in assessing an appropriate regulatory response.
       An initial question is whether the range of recommended primary standards for fine
PM would provide adequate protection against visibility impairment across the country. The
range being considered for an annual PM-fine standard  is  J 5 //g/m3 to  less than 30 /xg/m3 and
the range under consideration for a 24-hour standard is  25 //g/m7 to less than 85  /zg/m'.
-------
                                Table VII-6
       PERCENTAGE CONTRIBUTION BY SOURCE CATEGORY TO FINE PARTICLE
     (AND PRECURSOR) EMISSIONS IN THE EAST. SOUTHWEST, AND NORTHWEST
EAST
Electric utilities
Diesel-fueled mobile sources
Gasoline vehicles
Petroleum and chemical industries
Industrial coal combustion
Residential wood burning
Fugitive dust (on-road/off-road traffic)
Feedlots and livestock waste mgmt.
Miscellaneous
SOUTHWEST
Electric utilities
Diesel-fueled mobile sources
Gasoline vehicles
Petroleum and chemical industries
Copper smelters
Fugitive dust (on-road/off-road traffic)
Residential wood burning
Feedlots and livestock waste mgmt.
Miscellaneous
NORTHWEST
Electric utilities
Diesel-fueled mobile sources
Gasoline vehicles
Petroleum and chemical industries
Residential wood burning
Forest management burning
Fugitive dust (on-road/off-road traffic)
Feedlots and livestock waste mgmt.
Primary metallurgical process
Organic solvent evaporation
Miscellaneous
SOx
78.0
1.5
1.0
4.5
7.0
—
—
—
8.0
SOx
33
12
5
22
19
-
-
-
9
SOx
30
12
4
19
-
-
-
-
8
-
27
Organic
Particles
_
-
34
—
-
20
_
-
46
Organic
Particles
_
5
38
—
-
-
8
-
49
Organic
Particles
-
-
15
-
22
45
-
-
-
-
18
VOC's
_
-
31
11
-
13
—
-
45
VOC's
_
_
42
12
-
-
5
-
41
VOC's
-
-
31
10
25
13
-
-
15
15
6
Elemental
Carbon
_
47
29
_
-
15
—
-
9
Elemental
Carbon
_
52
31
—
-
-
6
-
11
Elemental
Carbon
—
37
16
-
22
20
-
-
-
-
5
Suspended
Dust
_
-
-
—
-
—
100
—
-
Suspended
Dust
_
_
-
_
-
100
-
—
-
Suspended
Dust
—
-
-
-
—
-
100
—
-
_
-
NH3
-
-
-
—
-
—
-
66
34
NH3
_
—
-
—
-
—
-
75
25
NH3
—
—
-
-
-
-
—
81
—
—
19
NOx
39
16
26
—
-
—
—
-
19
NOx
19
23
32
_
—
—
-
_
26
NOx
8
29
36
-
-
-
—
_
-
—
27
Source: National Research Council, Protecting Visibility in National Parks and Wilderness Areas. National Academy Press, 1993.
-------
                                            VII-9b
LOCATION
Archuleta County, CO
Baltimore, MD
Boston, MA
Cleveland, OH
Columbia, SC
Dallas-Fort Worth, TX
Detroit, MI
El Paso, TX
Fresno, CA
Houston, TX
Los Angeles-Long Beach, CA
Minneapolis, MN
Nashville, TN
New York, NY
Philadelphia, PA
Pittsburgh, PA
Portland, OR
Portland, ME
Riverside, CA
Salt Lake City, UT
St. Louis, MO
Steubenville, OH
Syracuse, NY
Winston-Salem, NC
NUMBER
OF
MONITORS
1
2
1
1
2
1
4
1
3
1
2
1
1
4
1
2
5
1
2
3
6
4
2
2
ANNUAL MEAN,
RANGE OF
HIGHEST VALUES
FOR DIFFERENT
MONITORS,
YEARS 1983-1993
(in /ig/m3)
22.7
24.7-26.1
20.2
28.4
22.3 - 33.0*
13.6
17.3 - 25.4*
14.5
15.4 - 26.0
16.6
27.5 - 32.0
13.6
28.6
21.9 - 47.0*
26.0
25.7 - 26.6
10.2 17.2
39.9*
11.0-43.3
14.0 - 52.9*
14.7 16.9
16.6 - 25.7
20.0-40.8*
23.4 24.7
SECOND HIGHEST
MAXIMUM 24-HOUR
VALUE,
RANGE OF HIGHEST
VALUES FOR DIFFERENT
MONITORS, YEARS 1983-
1993 (in Mg/m3)
48
45- 106
55
55
43 -60
37
44-73
58
58 100
37
70 - 88
38
64
51 -91
47
59 82
19-60
50
22 - 114
14-91
38 -49
42- 81
47 -72
51 -56
                                         Source: U.S. EPA, monitored values from AIRS database

*These dau are unreliable due to incomplete and/or unrepresentative monitoring.
Table VII-7       Annual Average and Second Highest Maximum Fine PM Levels for
                 Selected U.S. Cities.
-------
                     VII-9c
Location
Wash,
DC
So.
Calif.
Sulfate
49.0
14.4
Nitrate
16.0
44.4
Organics
16.2
18.2
Elemental
Carbon
11.9
9.0
Soil and
Coarse
6.9
13.9
                             Source: Sisler « al. 1993
Table VII-8.  Percentage contributions of particle types to annual
average total light extinction in the Washington,  D.C. and southern
California areas.
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External Review Draft                                                     DO Not Quote or Cite
November 1995                             VII-10
Table Vn-7 presents monitored fine particle annual averages and second highest maximum
levels for several major U.S. cities.  Analysis of these data suggests that adoption of an
annual fine particle standard in the lower half of the recommended range, in combination
with adoption of a 24-hour standard in the lower half of the recommended range, would be
expected to lead to reductions in annual average fine particle concentrations in many urban
areas nationally, and possibly in broader areas in the East if regional attainment strategies are
emphasized.  To examine any expected visibility improvement resulting from these
reductions requires an understanding of the relationship between fine particle loadings and
visibility. Figure VH-5 shows that visibility change is sensitive to current fine particle
concentrations and their associated extinction efficiency. To achieve a given amount of
visibility improvement, a larger reduction in fine particle concentration is required in areas
with higher existing concentrations, such as the East.  Expected reductions in fine particle
concentrations resulting from adoption of the primary fine particle standards in the lower half
of the recommended range  is expected to result in maintained or improved visibility in many
urban areas and in a broader area in  the East.  Improvement of visibility would be greater if
regional fine particle attainment strategies are emphasized.  In its 1993 Report to Congress
on the effects of Clean Air Act programs on visibility in mandatory federal Class I  areas,
EPA examined the impact of expected regional sulfur dioxide reductions under the acid rain
program (U. S.  EPA 1993).  This report estimated that regional sulfate levels would be
reduced over a wide area in the eastern  U.S. by the year 2010, resulting in potential
improvements in annual average visibility for the region.  The analysis projected no expected
improvement in the rural West.  Any additional regional strategies to attain fine particle
standards could lead to further visibility improvements, particularly in the East.  However,
there is no evidence that adoption of the primary fine particle standards in the lower half of
the recommended range will eliminate adverse impacts of fine particles on visibility.
-------
                                   Vll-lOa
            400
                                                       bRg = 0.01 km'1
                                              bext/FINE MASS = 0.004 krTT1/Mg/m3
                                                      HUMIDITY<60%
                                               ARROWS INDICATE
                                               ADDITION OF 1 //g/m3
                                               OF FINE PARTICLES
                            10            20           30           40

                            FINE PARTICLE CONCENTRATION, pg/rrT3
Figure VII-5. Effects of fine particle increments on calculated visual range.  Addition of 1
/Ag/m3 to a clean atmosphere reduces visual range by 30 percent.  Addition of the same
amount when background visual range is 35 km (20 miles) produces a 3 percent reduction.
-------
External Review Draft                                                      Do Not Quote or Cite
November 1995                            VII-11
       The staff has also considered whether the adoption of a national secondary standard
would provide adequate protection of public welfare across the country.  Due to the regional
variability in background fine particle levels, the staff has concluded that a national
secondary standard could not achieve this objective.  The data presented in table VII-4
indicates that current annual average light extinction levels on the Colorado plateau are about
equal to background levels in  the East.  In other words, a national secondary standard set to
maintain or improve visibility conditions in the Colorado plateau would have to be set at or
below natural background levels in the East.  Conversely, a national secondary standard that
would be both attainable and improve visibility in the East would permit further degradation
in the West.
       A more promising option is to establish a regional haze program under section 169A
of the Clean Air Act, which would address the existing adverse effects of fine particles on
visibility in both class I and non-class I areas.   Section 169A established a national goal of
"the prevention of any future, and the remedying of any existing, manmade impairment of
visibility in mandatory class I areas." The EPA is required  to establish programs  to ensure
reasonable progress toward the national goal.  These programs are to be implemented by the
States and can be regionally specific.
       Much progress has  been made in technical areas important to the successful
implementation of a regional haze program, including areas  such as visibility monitoring,
regional scale modeling, and scientific knowledge of the regional effects of particles on
visibility. The National Academy of Sciences 1993  report on visibility protection  confirmed
this point:
       Current scientific knowledge is adequate and control  technologies are available
       for taking regulatory action to improve and protect visibility.  However,
       continued national progress  toward this goal will require a greater commitment
       toward atmospheric research,  monitoring, and emissions control  research and
       development.
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External Review Draft                                                      Do Not Quote or Cite
November 1995                            VII-12
       In addition, it is expected that the development of a regional haze program will have
associated benefits outside of mandatory class I areas.  The National Academy of Sciences
concluded that:
       Efforts to improve visibility in Class I areas also would benefit visibility
       outside these areas.  Because most visibility impairment is regional in scale,
       the same haze that degrades visibility within or looking out from a national
       park also degrades visibility outside it.  Class I areas cannot be regarded as
       potential islands of clean air in a polluted sea.
       Based on the above considerations, the staff recommends  that the Administrator
consider establishing a regional haze program under section 169A of the Act, in conjunction
with the recommended fine particle primary standards,  as the most effective means of
addressing the welfare effects associated with visibility impairment. Together, the two
programs and associated control strategies should adequately protect against the adverse
effects of fine particle pollutants on visibility.
C.     Effects of PM on  Materials Damage and Soiling
       The deposition of airborne particles can become a nuisance,  reducing the aesthetic
appeal of buildings and culturally important articles through soiling, and contribute directly
(or in conjunction with other pollutants) to structural damage by  means of corrosion or
erosion.  These potential  effects are discussed more fully below.   The relative importance of
particle size, composition, and other environmental factors (i.e.,  moisture, temperature,
sunlight, and wind) in contributing to the effects  is also considered.
1.     Materials Damage
       Particles affect materials principally by promoting and accelerating the corrosion of
metals, by degrading paints, and by deteriorating building materials such as concrete and
limestone. Particles contribute to these effects because of their electrolytic, hygroscopic, and
acidic properties, and their ability to sorb corrosive gases (principally sulfur dioxide).  The
staff review suggests that only chemically active  fine mode or hygroscopic  coarse mode
(mainly sea or road salt) particles contribute to such effects (U.S. EPA, 1986b).   While
particles have been qualitatively associated with damage to materials,  there are insufficient
data at present to relate such effects to specific particle pollution levels.  The following
-------
External Review Draft                                                     Do Not Quote or Cite
November 1995                            VII-13
discussion briefly outlines the available information on PM-related effects associated with
each category of material presented in the criteria document.
       a.     Effects on Metals
       The rate of metal corrosion depends on a number of factors, including the deposition
rate and nature of the pollutant; the influence of the metal protective corrosion film; the
amount of moisture present; variability in the electrochemical reactions; the presence and
concentration of other surface electrolytes; and the orientation of the metal surface (CD,
Chapter 9).   This  section briefly discusses the factors affecting metal corrosion set forth in
the criteria document.
       Nriagu (1978) and Sydberger (1977) conducted studies that highlighted the ability
metals have to form a protective film that slows corrosion rates.  Metals initially exposed to
low concentrations of SOX corroded at a slower rate than did samples continuously exposed to
higher concentrations.  This protective corrosion layer may, however, be affected by either
dry or wet deposition (CD, Chapter 9).
       The rate of metal corrosion decreases in the absence of moisture (CD, Chapter 9).
Moisture influences corrosion rates by providing a medium of conduction paths for
electrochemical reactions and a medium for water soluble air pollutants.  Schwartz (1972)
established that the corrosion rate  of a metal could increase by 20 percent for each one
percent increase in relative humidity above the minimum atmospheric moisture content that
allows corrosion to occur (i.e., critical  relative humidity).  Later studies by Haynie and
Upham (1974) and Sydberger and Ericsson (1977) supported Schwartz's theory.
       While particles alone  have  some effect on the early stages of metal corrosion, there is
insufficient evidence to relate such effects to specific particle levels.  One study (Goodwin et
al. (1969)) reported damage to steel, protected with  nylon screen, exposed to quartz particles
larger than 5 jim;  but the exposure time and concentration were not reported.  Barton (1958)
also found that dust contributed to the early stages of metal corrosion.   A number of the
studies evaluated concluded that particulate matter increased the corrosion rate  of sulfur
dioxides (Sanyal and Singhania, (1956); Yocom and Grappone, (1976); Johnson et al.,
(1977); Russell, (1976);  Walton et al.,  (1982)). Laboratory studies show mixed results as to
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whether catalytic species or conductance of the thin-film surface electrolyte is the cause of
the increases in corrosion rates (Walton et al., 1982; Skerry et al., 1988 a,b; Askey et al.,
1993).
       Results of actual field studies have not established a quantitative relationship between
particles and corrosion.  Thus, the independent effect of particles is not evident since SOj is
the controlling factor for determining corrosion rate (U.S. EPA, 1986b).  Edney et al. (1989)
exposed galvanized steel panels to actual field conditions in Research Triangle Park, NC and
Steubenville, OH between April 25  and December 28, 1987.  The panels were exposed under
the following conditions:  (1) dry deposition only; (2) dry plus ambient wet deposition; and
(3) dry deposition plus deionized water. The average concentrations for SO2 and paniculate
matter was 22 ppb and 70 /*g/m3 and < 1 ppb and 32 /tg/m3 for Steubenville and Research
Triangle Park, respectively. The runoff from the steel panel was analyzed and it was
concluded that the dissolution  of the steel corrosion products for both sites was likely the
result of deposited gas phase SO^ on the metal surface and not paniculate matter.
Another  study conducted by Butlin et al. (1992) also demonstrated that the corrosion of mild
steel and galvanized steel was  SO2-dependent. Butlin et al. monitored the corrosion of steel
samples by SO2 and ozone under artificially fumigated environments, and NO2 under natural
conditions.  Annual average SO2 concentrations ranged from 2.1 jtg/m3 in a rural area to 60
ptg/m3 in on of the SCVfuniigated locations.  Annual average NO2 concentrations ranged
from 1.5 to 61.8 ptg/m3. The  study concluded that corrosion of the steel samples was
primarily dependent on the long-term SO2 concentration and was only minimally affected by
nitrogen oxides.
       b.    Effects on Paint
       Paints undergo natural  weathering processes from  exposure to environmental factors
such as sunlight,  moisture, .fungi, and varying temperatures. In addition to the natural
environmental factors, studies  show paniculate matter exposure may give painted surfaces a
dirty appearance (CD, Chapter 9).  Several studies also suggest that particles serve as
carriers of other more corrosive pollutants, allowing the pollutants to reach the underlying
surface or serve as concentration sites for  other pollutants (Cowling and Roberts, 1954).
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November 1995                            VII-15
       A number of studies have shown some correlation between paniculate matter and
damage to automobile finishes.  Fochtman and Langer (1957) reported damage to automobile
finishes due to iron particles emitted from nearby industrial facilities.  General Motors
conducted field tests in Jacksonville, Florida to determine the effect of various
meteorological events, the chemical composition of rain and dew, and the ambient air
composition during the event, on automotive paint finishes.  Painted (basecoat/clearcoat
technology) steel panels were exposed for varying time periods, under protected and
unprotected condition.  The researcher concluded that calcium sulfate formed on the painted
surface by  the reaction of calcium from dust and sulfuric acid contained in rain or dew.  The
damage to the paint finish increased with  increasing days of exposure (Wolff et al., 1990).
       Paint films permeable to water are also susceptible to penetration by acid forming
aerosols (U.S. EPA, 1995).  Baedecker et al.  (1991) reviewed studies dealing with solubility
and permeability of SO2  in paints and polymer films.  These studies showed permeation and
absorption  rates varied depending on  the formulation of the paint.
       Studies reported in the criteria document (Spence et al., (1975); Campbell et al.,
(1974); Haynie and Spence,  (1984); Yocom and Grappone, (1976); and Yocom and Upham,
(1977)) support the conclusion that gaseous pollutants contribute to the erosion rates of
exterior paints.
       c.     Effects on Stone
       Damage to calcareous stones (i.e., limestone, marble and carbonated cemented stone)
has been attributed to deposition of acidic particles.  Moisture and salts are considered the
most important factors in building material damage (CD, Chapter 9). However, many other
factors (such as normal weathering and microorganism damage) also seem  to play a part in
the deterioration of inorganic building materials.  The relative importance of biological,
chemical, and physical mechanisms has not been studied to date. Thus, the link between
ambient pollutant concentrations and damage to various building stones is difficult to
quantify.
       Baedecker et al. (1991) reported that 10 percent of chemical weathering of marble and
limestone was  caused by wet deposition of hydrogen ions from all acid species.  Dry
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November 1995                             VII-16
deposition of SO2 between rain events caused 5 to 20 percent of the chemical erosion of
stone, and dry deposition of nitric acid was responsible for 2 to 6 percent of the erosion
(Baedecker et al.  1991).
       Under high wind conditions, particulates result in slow erosion of the surfaces, similar
to sandblasting  (Yocom and Upham, 1977).
       d.     Effects on Electronics
       Exposure to ionic dust particles can contribute significantly to the corrosion rate of
electronic devices, ultimately leading to failure.  Particles derived from both natural and
anthropogenic sources and ranging in size from tens of angstroms to one /xm can cause
corrosion of electronics because many are sufficiently hygroscopic and corrosive, at normal
relative humidities, to react directly with  non-noble metal and passive oxides, or to form
conductive moisture films on insulating surfaces to cause electrical leakage.  The effects of
particles on electronic components were first reported by telephone companies who reported
that particles high in nitrates caused corrosion, cracking, and ultimate failure of wire spring
relays (Hermance, 1966; McKinney and Hermance,  1969).  More recently, Sinclare (1992)
and Frankenthal (1993) have reported that anthropogenically-derived particles penetrating into
indoor environments can contribute to the corrosion  of electronics.
2.     Staff Considerations Pertaining to  the Effects of PM on Materials Damage
       While particles, particularly in conjunction with sulfur dioxide, have been
qualitatively associated with damage to materials, there is insufficient data available to relate
such damage to specific particle levels in  the ambient air. Absent better quantitative data,
the staff does not believe the Administrator should consider a separate secondary standard
based on materials damage.
3.     Soiling
       Soiling is the accumulation of particles on the surface of an exposed material resulting
in the degradation of its appearance.  When such accumulation produces  sufficient changes in
reflection from  opaque surfaces and reduces light transmission through transparent materials,
the surface will become perceptibly dirty  to the human observer.  Soiling can be remedied by
cleaning or washing, and depending on the soiled material, repainting.
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November 1995                            VII-17
       Determination of what accumulated level of paniculate matter leads to increased
cleaning or repainting is difficult.  For example, Carey (1959) found that the appearance of
soiling only occurred when the surface of paper was covered with dust specks spaced 10 to
20 diameters apart.  When the contrast was strong, e.g., black on white, it was possible to
distinguish a clean surface from a surrounding dirty surface when only 0.2 percent of the
areas was covered with specks, while 0.4 percent of the surface had to be covered with
specks with a weaker color contrast.
       Hancock et al. (1976) found that with maximum contrast, a 0.2 percent surface
coverage (effective area coverage;  EAC) by dust can be perceived against a clean
background.  A dust deposition level of 0.7 percent EAC was needed before the object was
considered unfit for  use. The minimum perceivable difference between varying gradations of
shading was  a change of about 0.45 percent EAC. Using the information on visually
perceived dust accumulation, Hancock et al. (1976) concluded that dustfall rates of less than
0.17 EAC/day would be tolerable to the general public. Similar studies have not been
reported for other soiling  effects.
       Despite the observation that airborne particles soil a wide range of man-made
materials, there is only limited information available  with respect  to size and composition of
the culpable particles.  In  general,  the soiling of fabrics and vertical surfaces has been
ascribed to fine particles,  particularly dark, carbonaceous materials.  Soiling of horizontal
surfaces may result from deposition of a wide range of particles, including coarse mode
dusts.
       An important consideration in assessing soiling potential is deposition velocity, which
is defined as flux divided  by concentration.   Deposition velocity is a function of particle
diameter, surface orientation and roughness, wind speed, atmospheric stability, and particle
density.  As  a result, soiling is expected to vary v/ith the size distribution of particles within
an ambient concentration,  whether the surface is positioned horizontally or vertically, and
whether the surface  is rough or smooth (CD, Chapter 9).
       Theoretically, coverage of horizontal surfaces will be related to particle surface areas
and deposition velocity. Particle surface areas per unit mass decreases linearly with  diameter
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November 1995                             VII-18
(assuming spherical particles), while, under quiescent conditions, deposition velocity
increases with the square of the diameter.  Under such conditions, large particles would
result in more soiling than an equivalent mass of smaller particles.  Although second order
effects may enhance fine particle deposition relative to larger particles, deposition velocity
data still suggest substantially higher deposition on  horizontal surfaces for particles larger
than 10 /xm than for smaller particles (U.S. EPA, 1982b).
       The increasing soiling potential associated with increased particle size is mitigated by
lighter particle color, effects  of rainfall, smaller transport distance from sources and
markedly lower penetration of larger particles to indoor surfaces (relative  to smaller
particles).  Because these conflicting factors have not been fully evaluated, it is not possible
to make clear particle size divisions with respect to soiling of horizontal surfaces.
       The time interval that it takes to transform horizontal and vertical surfaces  from clean
to perceptibly dirty is generally determined by particle composition and rate of deposition.
The process is influenced by the location (sheltered or unsheltered) and  spatial alignment of
the material, the texture and  color of the surface relative to the particles, and  meteorological
variables such as moisture, temperature, and wind speed.
       Haynie and Lemmons (1990) conducted a soiling study in a relatively rural
environment in Research Triangle Park, North Carolina. The study was designed to
determine how various environmental factors contribute to  the rate of soiling of white painted
surfaces, which are highly sensitive to soiling by dark particles and represent  a large fraction
of all man-made surfaces exposed in the environment. Hourly rainfall and wind speed, and
weekly data for dichotomous sampler measurements and TSP concentration were monitored.
Gloss and flat white paints were applied to hardboard house siding surfaces and exposed
vertically and horizontally  for 16 weeks, either sheltered or unsheltered from  rainfall.
Measurements, including reflectance, were taken at 2, 4, 8, and 16 weeks.  Based on the
results of this study, the authors concluded that: (1) coarse mode particles initially contribute
more to soiling of both horizontal and vertical surfaces than fine mode particles;  (2) coarse
mode particles, however, are more easily removed  by rain than are fine mode particles; (3)
for sheltered surfaces, reflectance changes are proportional to surface coverage by particles,
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November 1995                             VII-19
and particle accumulation is consistent with deposition theory; (4) rain interacts with particles
to contribute to soiling by dissolving or desegregating particles and leaving stains; and (5)
very long-term remedial actions are probably taken because of the accumulation of fine
rather than coarse particles (Haynie and Lemmons, 1990).
       Creighton et al.  (1990) reported that horizontal surfaces soiled faster than  vertical
surfaces and that large particles were primarily responsible for the soiling of horizontal
surfaces not exposed to rainfall.  Soiling was related  to the accumulated mass of particles
from both the fine and coarse fraction.
       Fine mode black smoke and motor vehicle exhaust have been  associated with the
soiling of building material and facades (Tarrat and Joumard, 1990; Lanting, 1986).
       Ligocki et al. (1993) studied the potential soiling of art work  in five Southern
California museums.  The authors concluded that a significant fraction of fine elemental
carbon and  soil dust particles  had penetrated to the indoor atmosphere of the museums
studied and may constitute a soiling hazard  to displayed  art work. The seasonally averaged
indoor/outdoor ratios for paniculate matter  mass  concentrations ranged from 0.16 to 0.96 for
fine particles and  from  0.06 to 0.53 for coarse particles, with lower values observed for
building with sophisticated ventilation systems  that include filters for particulate removal.
4.     Societal Costs
       a.     Soiling/Property Value
       The effect of particles  on aesthetic quality depends in part on  human perception of
pollution.  The reduction of aesthetic quality may arise from the  soiling of buildings or other
objects of historical or social interest from the  mere dirty appearance of a neighborhood. A
number of studies have indicated that such perceptions of neighborhood degradation are
revealed indirectly through effects on the value of residential property.  That is, when
residential properties similar in other respects are compared, the  properties in the more
highly polluted areas typically have lower value.
         Freeman (1979), reporting on 14 prope/ty value studies  that used particulate matter
or dustfall as one of their pollutant measures, noted that the results generally supported the
premise  that property values are affected  by the full range of particle pollution. He
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November 1995                             VII-20
cautioned, however, that direct comparison of the monetary results is not possible since the
studies cover a number of cities and use different data bases, empirical techniques, and
model specifications.
       The extent to which the city-specific results represent soiling as opposed to
perceptions of the effects of particles on health and visibility is not clear. Therefore, the
results of these studies cannot provide reliable quantitative estimates of the effects of soiling
on property values (U.S. EPA, 1982b).
       b.     Soiling/Materials
       Airborne particles soil a wide range of materials in all sectors of the economy.
Assuming that these sectors are not as well off in a dirtier state as a cleaner one, soiling will
result in an economic cost to society.  While the household sector has been examined by a
number of investigators,  their results have been questioned because of methodology
problems and their failure to appropriately address particle size, composition,  and deposition
rates.   As a  result, no single study has produced a completely satisfactory estimate of soiling
costs for the household sector. It is unfortunate that little or no effort has been expended to
account for soiling costs  in the commercial, manufacturing, or public sectors.   Results from
MathTech, Inc. (1983) suggest that soiling  costs for the manufacturing sector  alone could be
significant.
       In the review of effects of household soiling,  the staff paper has relied principally on
Booz, Allen and Hamilton, Inc., (1970); Watson and Jaksch, (1978, 1982) [which was cited
in the CD and discussed  in more detail in the 1982 criteria document]; and MathTech, Inc.,
(1983) to derive estimates of household soiling costs.  For the year 1970, the estimate for
amenity loss due to exterior household soiling was estimated to range  form 1  to 3.5 billion
dollars (1978 dollars).  The 14 /tg/m3 reduction in U.S. annual TSP levels between 1970 and
1978 was estimated to  have, resulted in an annual benefit for the year 1978 of 0.2 to 0.7
billion dollars or 14 to 50 million dollars for each jig/m3 of reduction  (U.S. EPA,  1982a).
MathTech, Inc. (1983) estimated household soiling costs in the range of $88.3 million to
$1.2 billion (1980 dollars) for attaining the primary PM10 standard nationwide.  Gilbert
(1985) used a household  production function  framework to design and estimate  the short-run
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November 1995                             VII-21
costs of soiling. The results were comparable to those reported by MathTech (1983).
Finally, McClelland et al. (1991) concluded that households were willing to pay $2.70 per
/ig/m3 change in particle level to avoid soiling effects.
       Haynie (1989), using fine and coarse mode particle levels calculated from 1987 EPA
AIRS data for PMio and TSP, estimated that $1.74 billion of annual national residential
repainting costs could be attributed to soiling (using national average painting costs and
frequencies). Haynie and Lemmons (1990) estimated that the national soiling costs associated
with repainting the  exterior walls of houses probably were within the range of $400 to $800
million a year in  1990. This lower estimate, as compared to Haynie (1989), reflects that
households in dirtier areas may not respond with average behavior but mitigate their behavior
by (1) accepting greater reductions in reflectance before repainting, (2) washing surfaces
rather than painting as often, or (3) selecting materials or  paint colors that do not tend to
show dirt.  Haynie  and Lemmons  (1990) extrapolated their findings for houses to all exterior
paint surfaces and produced a range from $570 to $1,140  million per year.
5.     Staff Considerations Pertaining to the Effects of PM on Soiling
       It is clear  that,  at high enough concentrations, particles become a nuisance and result
in increased cost and decreased enjoyment of the environment.  The available data are
limited, however, and do not permit any definitive findings with respect to societal costs or
provide clear quantitative relationships between ambient particle loading and soiling.   Absent
sufficient data,  the  staff concludes that there is not a sufficient basis to set a separate
secondary standard  based on soiling effects alone.  The recommended suite of primary
ambient air quality  standards and the regional haze program should reduce  the soiling  and
nuisance effects associated with particle pollution.   The effects associated with dustfall are
likely to be very localized and thus,  more appropriately addressed at  the local level.
D.    Summary  of Staff Conclusions and Recommendations on Secondary NAAOS
       This summary of staff conclusions ariii recommendations for the PM secondary
NAAQS draws from the discussions contained in the previous  sections of this Staff Paper.
The key findings  are:
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November 1995                            VH-22
1)     Anthropogenic fine particles impair visibility nationally.  The level of this impairment
       varies greatly from East to West, in terms of total loadings, pollutant mix, and
       resulting total light extinction.  Background levels of fine particles and humidity vary
       regionally as well, with the East having higher levels than the West.
2)     Because of regional variations in natural background levels of fine particles,  annual
       average humidity, pollutant mix, and  resulting total light extinction, the staff
       concludes that a national secondary standard to protect visibility would not be the
       most effective approach for addressing visibility impairment.  Therefore,  the staff
       recommends that the Administrator consider establishing regional haze regulations
       under section 169A of the Act.
3)     The available data assessed in the CD does not provide an adequate basis to establish
       a national secondary standard to protect against soiling and materials damage effects.
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                          PM STAFF PAPER
                            REFERENCES
Abbey, D. E.; Lebowitz, M. D.; Mills, P. K.; Petersen, F. F.;
     Beeson, W. L.; Burchette, R. J.  (1995) Long-term ambient
     concentrations of particulates and oxidants and development
     of chronic disease in a cohort of nonsmoking California
     residents. Inhalation Toxicol. 7: 19-34.

Abbey, D.E.; Ostro, B.E.; Petersen, F.; Burchette, R.J.  (1995b)
     Chronic respiratory symptoms associated with estimated long-
     term ambient concentrations of fine particulates less than
     2.5 microns in aerodynamic diameter (PM2.5) and other air
     pollutants.  J. of Exp. & Environ. Epidem. 5: 137-159.

Abbey, D.E.; Hwang, B.L.; Burchette, R.J.; Vancuren, T.; Mills,
     P.K. (1995c)  Estimated long-term ambient concentrations of
     PM10 and development of respiratory symptoms in a non-
     smoking population.  Arch, of Environ. Hlth:50(2).

Abbey, D.E.; Petersen, M.P.H.; Mills, P.K.; Beeson, W.L. (1993)
     Long-term concentrations of total suspended particulates,
     ozone, and sulfur dioxide and respiratory symptoms in a
     nonsmoking populations.  Arch, of Environ. Hlth:48: 33-46.

Abbey, D. E.; Mills, P- K.; Petersen, F. F.; Beeson, W. L. (1991)
     Long-term ambient concentrations of total suspended
     particulates and oxidants as related to incidence of chronic
     disease in California Seventh-Day Adventists. Environ.
     Health Perspect. 94: 43-50.

Ackermann - Leibrich et al., (in press).

Akira, S.; Kishimoro, T.; (1992) Ih-6 and Nf-IL6 in acute phase
     response and viral infection.  Immunol. Rev- 127:25-50.

Anderson, P. J.; Wilson, J. D.; Killer, F. C.  (1990) Respiratory
     tract deposition of ultrafine particles in subjects with
     obstructive or restrictive lung disease. Chest 97: 1115-
     1120.

Anuszewski, J.; Larson, T.V-; Koenig, J.Q. (1992)  Simultaneous
     indoor and outdoor particle light scattering measurements at
     nine homes using a portable nephelometer.  Presented at:
     meeting of the American Association for Aerosol Research;
     paper no. 3A.5.

Askey, A.; Lyon, S.B.; Thompson, G.E.; Johnson, J.B.; Wood, G.C.;
     Sage, P.W.; Cooke, M.J. (1993) Effect of fly-ash
     particulates on the atmospheric corrosion of zinc and mild
     steel.  Corros. Sci. 34:  1055-1081.
-------
Avol, E.L.; Linn, W.S.; Whynot, J.D.; Anderson, K.R.; Shamoo,
     D.A.; Valencia, L.M.; Little, D.E.; Hackney, J.D.  (1988a)
     Respiratory dose-response study of normal and asthmatic
     volunteers exposed to sulfuric acid aerosol in  the sub-
     micrometer size range.  Toxicol. Ind. Health 4:173-184.

Avol, E.L.; Linn, W.S.; Wightman, L.H.; Whynot, J.D.; Anderson,
     K.R.; Hackney, J.D.  (1988b) Short-term respiratory effects
     of sulfuric acid in  fog: a laboratory study of  healthy and
     asthmatic volunteers.  JAPCA 38:258-263.

Baedecker, P.A.; Edney, E.G.; Moran, P.J.; Simpson,  T.C.;
     Williams, R.S.  (1991)  Effects of acidic deposition on
     materials.  In: Irving, P.M., ed. Acidic deposition:  state
     of science and technology, volume III: terrestrial,
     materials, health and visibility effects.  Washington, DC:
     The U.S. National Acid Precipitation Assessment Program.
     (State of science and technology report no. 19).

Barton, K. (1958) The influence of dust on atmospheric corrosion
     of metals.  Werkst.  Korros. 8/9: 547-549.

Bates, D.V.  (1992)  Health indices of the adverse effects  of air
     pollution:  the question of coherence.  Environ. Res.
     59:336-349.

Bobak, M.; Leon, D. A. (1992) Air pollution and infant mortality
     in the Czech Republic, 1986-1988. Lancet  (8826): 1010-1014.

Booz, Allen and Hamilton, Inc.  (1970) Study to determine
     residential soiling  costs of particulate air pollution.
     Washington, DC:  U.S. Department of Health, Education, and
     Welfare, National Air Pollution Control Administration;
     Available from: NTIS, Springfield, VA; PB-250807.

Bouhuys, A.; Beck, G. J.; Schoenberg, J. B. (1978) Do present
     levels of air pollution outdoors affect respiratory health?
     Nature  (London) 276: 466-471.

Brauer, M., Koutrakis, P., Spengler, J.D.  Personal  exposures to
     acidic aerosols and  gases.  Environ. Sci. Tech. 1989; 23:
     1408-12.

Braun-Fahrlander, C.; Ackermann-Liebrich, U.; Schwartz, J.;
     Gnehm, H. P.; Rutishauser, M.; Wanner, H. U. (1992) Air
     pollution and respiratory symptoms in preschool children.
     Am. Rev. Respir. Dis. 145: 42-47.
-------
Brook, J.R.; Dann, T.F.; Burnett, R.T.  (In press).  The
     relationship among TSP, PMIO, PM2.5 and  inorganic constituents
     of atmospheric particulate matter at multiple Canadian
     locations.

Buechley, R.W. (1975).  SO2 Levels,  1967-1972  and Perturbations
     in Mortality.  Contract No. ES-5-2101.  Report available
     from National Institute of Environmental Health Sciences,
     Research Triangle Park, NC.

Burnett, R.T., Dales, R.; Krewski, D.; Vincent, R.; Dann, T.;
     Brook, J.F.  (1995) Associations between ambient particulate
     sulfate and admissions to Ontario hospitals for cardiac and
     respiratory diseases.  Am. J. Epidemiol. 142: 15-22.

Burnett, R. T.; Dales, R. E.; Raizenne, M. E.; Krewski, D.;
     Summers, P. W.; Roberts, G. R.; Raad-Young, M.; Dann, T.;
     Brook, J. (1994) Effects of low ambient levels of ozone and
     sulfates on the frequency of respiratory admissions to
     Ontario hospitals. Environ. Res. 65: 172-194.

Butlin, R.N.; Coote, A.T.; Devenish, M.; Hughes, I.S.C.;
     Hutchens, C.M.; Irwin, J.G.; Lloyd, G.O.; Massey, S.W.;
     Webb, A.H.; Yates, T.J.S. (1992)  Preliminary results from
     the analysis of stone tables from the National Materials
     Exposure Programme (NMEP). Atmos. Environ. Part B 26: 189-
     198.

Butlin, R.N.; Coote, A.T.; Devenish, M.; Hughes, I.S.C.;
     Hutchens, C.M.; Irwin, J.G.; Lloyd, G.O.; Massey, S.W.;
     Webb, A.H.; Yates, T.J.S. (1992)  Preliminary results from
     the analysis of metal samples from the National Materials
     Exposure Programme (NMEP). Atmos. Environ. Part B 26: 199-
     206.

Campbell, G.G.; Schurr, G.G.; Slawikowski, D.E.; Spence, J.W.
     (1974)  Assessing air pollution damage to coatings. J. Paint
     Technol. 46: 59-71.

Carey, W.F. (1959)  Atmospheric deposits in Britain: a study of
     dinginess.  Int. J. Air Pollut. 2: 1-26.

Chapman, R. S.; Calafiore, D. C.; Hasselblad, V.  (1985)
     Prevalence of persistent cough and phlegm in young adults in
     relation to Icing-term ambient sulfur oxide exposure.
     Am. Rev. Respir. Dis. 132: 261-267.

Chappie, M.; Lave, L. (1982) The health effects of air pollution:
     a reanalysis. J. Urban Econ. 12: 346-376.
-------
Chen, L. C.; Fine, J. M.; Qu, Q.-S.; Amdur, M. O.; Gordon, T.
     (1992) Effects of fine and ultrafine sulfuric acid aerosols
     in guinea pigs: alterations in alveolar macrophage function
     and intracellular pH. Toxicol. Appl. Pharmacol. 113:  109-
     117.

Chestnut, L.G.; Dennis, R.L.; Latimer, D. A.  (1994) Economic
     Benefits of Improvements in Visibility:  Acid Rain
     Provisions of the 1990 Clean Air Act Amendments.
     Proceedings of Aerosols and Atmospheric Optics:  Radiative
     Balance and Visual Air Quality- Air & Waste Management
     Association International Specialty Conference, pp. 791-802.

Chow, J.C. (1995)  Measurement Methods to Determine Compliance
     with Ambient Air Quality Standards for Suspended Particles.
     J. of the Air and Waste Management Association. May 1995.
     45:320-382.

CEPA/FPAC Working Group on Air Quality Objectives and Guidelines
     (1995).  National ambient air quality objectives for
     particulate matter less than 10 /xm (PM,0) .

Ciocco, A. and D.J. Thompson (1961).  A follow-up of Donora ten
     years after:  methodology and findings. J. Pub. Health 51:
     155-164.

Cohen, J.P-; Iwamiya, R.K. Particulate Matter Data Analysis for
     the NAAQS Project. Report prepared for the U.S. EPA by
     Systems Applications International, San Rafael, CA.
     February 24, 1995.

Cohen, J.P.; Noda, A.M.; Eberly, S.I.; Gray.- H.A. ; Iwamiya, R.K.;
     McAuliffe, K.A.; Looker, R.E. Statistical Support for the
     Particulate Matter NAAQS. Report prepared for the U.S. EPA
     by Systems Applications International, San Rafael, CA
     (SYSAPP-95/039). July 1995.

Cohen, S.; G.W. Evans; D. Stokols; D.S. Krantz (1986) Behavior,
     Health and Environmental Stress.  Plenum Press, New York,
     NY.

Cooper, R.L.; Goldman, J.M.; Harbin, J.J., eds.  (1991)  Aging and
     environmental toxicology: biological and behavioral
     perspective.  Baltimore, MD: John Hopkins University Press
     (series in environmental toxicology).

Costa, D.L.; Lehmann, J.R.; Smith, S.; Dreher, K.L. (1995)
     Amplication of particle toxicity to the lung by pre-existing
     inflammation. Am. J. Respir. Grit. Care Med.:151:A265.
-------
Costa, D.L.; Lehmann, J.R.; Frazier, L.T.; Doerfler, D.; Ghio, A.
     (1994)  Pulmonary hypertension:  a possible risk factor in
     particulate toxicity  (Abstract).  Am. Rev. Respir. Dis. 149
     (4, p. 2): A840.

Council on Environmental Quality (1978) Visibility Protection for
     Class I Areas, the Technical Basis.  Washington, DC.

Cowling, J.E.; Roberts, M.E. (1954) Paints, varnishes, enamels,
     and lacquers.  In:  Deterioration of materials:  causes and
     preventive techniques.  New York, NY:  Reinhold Publishing
     Corp.; pp. 596-645.

Crapo, J.; Miller, F.J.; Mossman, B.; Pryor, W.A.; Kiley, J.P-
     (1992)  Relationship between acute inflammatory responses to
     air pollutants and chronic lung disease.  Am. Rev. Respir.
     Dis. 145:1506-1512.

Creighton, P J.; Lioy, P. J. ; Haynie, F. H. ; Lemmons, T J. ;
     Miller, J. L.; Gerhart, J. (1990) Soiling by atmospheric
     aerosols in an urban industrial area.  J. Air Waste Manage.
     ASSOC. 40:  1285-1289.

Gulp, D.J.; Latchney, L.R.; Frampton, M.W.; Jahnke, M.R.; Morrow,
     P.E.; Utell, M.J.  (1995).  Composition of human airway
     mucins and effects after inhalation of acid aerosols. Am. J.
     Physiol.: in press.

Cupitt, L.T.; Glen, W.G.; Lewtas, J.  (1994) Exposure and risk
     from ambient particle-bound pollution in an airshed
     dominated by residential wood combustion and mobile sources.
     In: Symposium of risk assessment of urban air:  emissions,
     exposure, risk identification, and risk quantitation; May-
     June 1992; Stockholm, Sweden. Environ. Health Perspect. 102
     (suppl. 4): 75-84.

Dahl, A.R.; Snipes, M.B.; Muggenburg, B.A.; Young, T.C.  (1983)
     Deposition of sulfuric acid mists in the respiratory tract
     of beagle dogs.  J. Toxicol. Environ. Health 11:141-149.

Dassen, W.; Brunekreef, B.; Hoek, G.; Hofschreuder, P.; Staatsen,
     B.; De Groot, H.; Schouten, E.; Biersteker, K.  (1986)
     Decline in children's pulmonary function during an air
     pollution episode. J. Air Pollut. Control Assoc. 36:
     1223-1227.
-------
Delfino, R.J.; Becklake, M.R.; Hanley, J.A. (1993).  Reliability
     of Hospital Data for Population-based Studies of Air
     Pollution.  Arch, of Environ. Health 48:(No. 3):140-145.

Dieher, K.; Jaskot, R.; Kodavanti, U.; Lehmann, J.; Winsett, D.;
     Costa, D. (1995)  Role of Soluble Metals in Acute Pulmonary
     Toxicity of Residual Oil Fly Ash Particles.  (Abstract).  Am.
     J. Respir. Grit. Care Med. 151:A265.

Dockery, D.W.; Schwartz, J.; Pope, C.A., III. (1995).  Comment
     from original Investigators, in: Particulate Air Pollution
     and Daily Mortality:  Replication and Validation of Selected
     Studies.  Prepared by:  Health Effects Institute, 141
     Portland Street, Suite 7300, Cambridge, MA 02139.  August
     1995.

Dockery, D. W.; Pope, C. A., III. (1994) Air pollution and
     mortality: the authors reply [letter], N. Engl. J. Med. 330:
     1238.

Dockery, D. W.; Pope, C. A., III. (1994) Acute respiratory
     effects of particulate air pollution. Annu. Rev. Public
     Health 15: 107-132.

Dockery, D. W.; Pope, C. A., Ill; Xu, X.; Spengler, J. D.; Ware,
     J. H.; Fay, M. E.; Ferris, B. G., Jr.; Speizer, F. E.  (1993)
     An association between air pollution and mortality in six
     U.S. cities. N. Engl. J. Med. 32y: 1753-1759.

Dockery, D. W.; Schwartz, J. (1992)  The authors' response to
     Waller and Swan. Am. J. Epidemiol. 135: 23-25.

Dockery, D.W.; Schwartz, J.; Spengler, J.D. (1992)  Air pollution
     and daily mortality: associations with particulates and acid
     aerosols.  Environ. Res. 59: 362-373.

Dockery, D. W.; Speizer, F. E.; Stram, D. O.; Ware, J. H.;
     Spengler, J. D.; Ferris, B. G., Jr. (1989) Effects of
     inhalable particles on respiratory health of children. Am.
     Rev. Respir. Dis. 139: 587-594.

Dockery, D. W.; Ware, J. H.; Ferris, B. G., Jr.; Speizer, F. E.;
     Cook, N. R.; Herman, S. M. (1982) Change in pulmonary
     function in children associated with air pollution episodes.
     J. Air Pollut. Control Assoc. 32: 937-942.

Dreher, K.; Jaskot, R.; Koduvanti, J.; Lehmann, J.; Winsett, D.;
     Costa, D. (1995)  Role of soluble metals in acute pulmonary
     toxicity of residual oil fly particles.  (Abstract).  Am. J.
     Respir. Crit. Care Med. 151:A265.
-------
Dusseldorf, A.; Kruize, H.; Brunekreef, B.; Hofschreuder, P.; de
     Meer, G.; van Oudvorst, A. B. (1994) Acute effects of PM10
     and airborne iron on respiratory health: a panel study among
     adults living near a steel industry in the Netherlands.
     Am. J. Respir. Grit. Care Med.: submitted.

Dye, J.A.; Richards, J.R.; Dreher, K.L.  (1995)  Injury of rat
     tracheal epithelial cultures by exposure to ozone and/or
     residual oil fly ash. (Abstract) Am. J. Respir. Grit. Care
     Med. 15HA265.

Edney, E.O.; cheek, S.F.; Corse, E.W.; Spence, J.W.; Haynie, F.H.
      (1989) Atmospheric weathering caused by dry deposition of
     acidic species.  J. Environ. Sci. Health Part A 24: 439-457.

El-Fawal, H.A.N.; Schlesinger, R.B.  (1994)  Nonspecific airway
     hyperresponsiveness induced by inhalation exposure to
     sulfuric acid aerosol: an invitro assessment.  Toxicol.
     Appl. Pharmacol. 125:70-76.

Euler, G.L.; Abbey, D.E.; Hodgkin, J.E.; Magie, A.R. (1988)
     Chronic obstructive pulmonary disease symptom effects of
     long-term cumulative exposure to ambient levels of total
     oxidants and nitrogen dioxide in California Seventh-Day
     Adventist residents. Arch, of Environ. Hlth 43:279-285.

Fairley, D. (1990) The relationship of daily mortality to
     suspended particulates in Santa Clara county, 1980-86.
     Environ. Health Perspect. 89: 159-168.

Fine, J.M.; Gordon, T.; Thompson, J.E.; Sheppard, D. (1987)  The
     role of titratable acidity on acid aerosol-induced
     bronchoconstriction.  Am. Rev. Respir. Dis. 135:826-830.

Firket, M. (1931) Sur les causes des accidents survenus dans la
     vallee de la Meuse, lors des brouillards de decembre 1930
      [The causes of accidents which occurred in the Meuse Valley
     during the fogs of December 1930]. Bull. Acad. R. Med.  Belg.
     ll[ser. 5]: 683-741.

Fishman, A.P. (1976)  Chronic cor-pulmonale.  Am. Rev. Resp. Dis.
     114:775-794.

Fochtman, E.G.; Langer, G. (1957) Automobile paint damaged by
     airborne iron particles.  J. Air Pollut. Control Assoc. 6:
     243-247.

Frampton, M. W.; Morrow, P. E.; Cox, C.; Levy, P. C.; Condemi, J.
     J.; Speers, D.; Gibb, F. R.; Utell, M. J.  (1995) Sulfuric
     acid aerosol followed by ozone exposure in healthy and
     asthmatic subjects. Environ. Res.: in press.
-------
Frampton, M.W.; Voter, K.Z.; Morrow, P.E.; Roberts, N.J., Jr.;
     Gulp, D.J.; Cox, C.; Utell, M.J.  (1992)  Sulfuric acid
     aerosol exposure in humans assessed by bronchoalveolar
     lavage.  Am. Rev. Respir. Dis. 146:626-632.

Frankenthal, R.P-; Lobnig, R.; Siconolfi, D.J.; Sinclair, J. D.
     (1993) Role of particle contamination in the corrosion of
     electronic materials and devices, J. Vac. Sci. Technol. A
     11:  2274-2279.

Freeman, A.M., III.  (1979)  The benefits of environmental
     improvement: theory and practice.  Baltimore, MD: The Johns
     Hopkins University Press.

Gardner, D.E.; Miller, F.J.; Illing, J.W.; Kirtz, J.M. (1977).
     Increased Infectivity with Exposure to Ozone and Sulfuric
     Acid.  Tox. Lett. 1:59-64.

Gergen, P.J.; Weiss, K.B. (1992)  The  increasing problem of
     asthma in the United States.  Am. Rev. Respir. Disease.
     146:823-824.

Ghio, A.J.; Hatch, G.E.  (1993)  Lavage phospholipid concentration
     after silica installation in the rat is associated with
     complexed [fe3+] on the dust surface.  Am. J. Respir. Cell
     Mol. Biol. 8:403-407.

Ghio, A.J.; Kennedy, T.P.; Whorton, A.R.; Crambliss, A.L.; Hatch,
     G.E.; Hoidal, J.R.  (1992)  Role of surface complexed iron
     for oxidant generation and lung inflammation induced by
     silicates.  Am. J. Physiol. 263:L511-L518.

Ghio, A.J.; Jaskot, R.H., Hatch, G.E.  (1994)  Lung injury after
     silica instillation is associated with an accumulation of
     iron in the rat.  (Abstract) Am. J. Respir. Crit. Care Med:
     149:A453.

Glasser, M., and L. Greenburg  (1971).  Air pollution and
     mortality and weather, New York City, 1960-64.  Arch.
     Environ. Health 22:334-343.

Glezen, W. P. (1989) Antecedents of chronic and recurrent lung
     disease: childhood respiratory trouble. Am. Rev. Respir.
     Dis. 140: 873-874.

Godleski, J.J.; Hatch, V.; Hauser, R.; Christian!, D.; Gasula,
     G.; Sioutas, C.  Ultrafine particles in lung macrophages of
     healthy people.  Am. J. Respir. Crit. Care Med. 1995;
     151:A264.
-------
Gold, D. R.; Tager, I. B.; Weiss, S. T.; Tosteson, T. D.;
     Speizer, F. E. (1989) Acute lower respiratory illness in
     childhood as a predictor of lung function and chronic
     respiratory symptoms. Am. Rev. Respir. Dis. 140: 877-884.

Goodwin, J.E.; Sage, W.; Tilly, G.P. (1969) Study of erosion by
     solid particles.  Proceedings of the Institution of
     Mechanical Engineers 184(15): 279-292.

Hancock, R.P.; Esmen, N.A.; Furber, C.P- (1976)  Visual response
     to dustiness.  J. Air Pollut. Control Assoc. 26: 54-57.
     Citations: 0024, 10; 0150, I; 0671, 09.

Hausman, J. A.; Ostro, B. D.; Wise, D. A. (1984) Air pollution
     and lost work. Cambridge, MA: National Bureau of Economic
     Research; NBER working paper no. 1263.

Haynie, F. H.  (1989) Environmental factors affecting the
     corrosion of galvanized steel.  In:  Dean,  S. W.; Lee,
     T.S., eds. Degradation of metals in the atmosphere:  a
     symposium sponsored by ASTM Committee G-l on corrosion of
     Metals; May 1986; Philadelphia, PA.  Philadelphia, PA:
     American Society for Testing and Materials; pp. 282-289.
     (ASTM Spec. Tech. Publ. 965).

Haynie F. H.; Lemmons, T. J. (1990) Evaluation of an atmospheric
     corrosion rate monitor as a time-of-wetness meter.  Mater.
     Perform. 31: 48-52.

Haynie, F.H.; Spence, J.W.  (1984)  Air pollution damage to
     exterior household paints.  J. Air Pollut. Control Assoc.
     34: 941-944.  Citations: 0082, 12; 0671, 09; 0746, 05.

Haynie, F. H.; Upham, J.B (1974)  Correlation between corrosion
     behavior of steel and atmospheric pollution data.  In:
     Coburn, S. K., ed. Corrosion in natural environments:
     presented at the 76th annual meeting American Society for
     Testing and Materials; June 1973; Philadelphia, PA; pp. 33-
     51.  (ASTM special technical publication 558).

Health Effects Institute.  Particulate Air Pollution and Daily
     Mortality - Replication and Validation of Selected Studies.
     Report prepared by:  Health Effects Institute, 141 Portland
     Street, Suite 7300, Cambridge, MA 02139.  August 1995.

Hefflin, B. J.; Jalaludin, B.; McClure, E.; Cobb, N.; Johnson, C,
     A.; Jecha, L.; Etzel, R. A. (1994) Surveillance for dust
     storms and respiratory diseases in Washington State, 1991.
     Arch. Environ. Health 49: 170-174.
-------
                                10

Helin, H. (1986)  Macrophage procoagulant factors - mediators  of
     inflammatory and neoplastic tissue lesions.  Med. Biol.
     1986; 64:167-176.

Hennekens, C.H.; Buring, J.E. (1987)  Epidemiology in Medicine.
     Little, Brown and Company.   Boston/Toronto.

Hermance, H.W.  (1966) Combatting the effects of smog on wire-
     spring relays.  Bell Lab. Rec. (February):  48-52.

Hill, A. B.  (1965) The environment and disease: association or
     causation? Proc. R. Soc. Med. 58: 295-300.

Hoek, G.  (1992) Acute effects of ambient air pollution episodes
     on respiratory health of children [thesis]. Wageningen, The
     Netherlands: Agricultural University of Wageningen.

Hoek, G.; Brunekreef, B. (1995)   Effect of photochemical air
     pollution on acute respiratory symptoms in children.  Am. J.
     Respir. Crit. Care Med. 151: 27-32.

Hoek, G.; Brunekreef, B. (1994)   Effects of low-level winter air
     pollution concentrations on respiratory health of Dutch
     children. Environ. Res. 64: 136-150.

Hoek, G.; Brunekreef, B. (1993)  Acute effects of a winter air
     pollution episode on pulmonary function and respiratory
     symptoms of children. Arch. Environ. Health 48: 328-335.

Ito, K.; Kinney, P-; Thurston, G. D. (1995)  Variations in PM10
     concentrations within two metropolitan areas and their
     implications to health effects analyses. Inhalation
     Toxicol.: accepted.

Ito, K.; Thurston, G. D.; Hayes, C.; Lippmann, M. (1993)
     Associations of London, England,  daily mortality with
     particulate matter, sulfur dioxide, and acidic aerosol
     pollution. Arch. Environ. Health 48: 213-220.

Janssen, N.A.H.; Hoek, G.; Harssema, H.; Brunekreef, B. (1995).
     A Relation Between Personal and Ambient PM10 Epidemiology;
     July 1995, Vol. 6, No. 4 Supplement.

Jaskot, R.H.; Costa, D.L.; Kodavanti,  P.; Lehmann, J.R.; Winsett,
     D.; Dreher, L.  Comparison of lung inflammation and airway
     reactivity in three strains of rats exposed to residual oil
     fly ash particles.  Am. J.  Respir. Crit. Care Med. 1995;
     151:A264.
-------
                                11

Jedrychowski, W.; Becher, H.; Wahrendorf, J.; Basa-Cierpialek, Z.
     (1990) A case-control study of lung cancer with special
     reference to the effect of air pollution in Poland.
     J. Epidemiol. Cominun. Health 44: 114-120.

John, W.; Wall, S.M.; Ondo, J.L.; Winklmayr, W. (1990) Modes in
     the size distributions of atmospheric inorganic aerosol.
     Atmos. Environ. Part A 24: 2349-2359.

Johnson, J.B.; Elliot, P-; Winterbottoro, M.A.; Wood, G.C.  (1977)
     Short-term atmospheric corrosion of mild steel at two
     weather and pollution monitored sites.  Corros. Sci. 17:
     691-700.

Johnson, K. G.; Loftsgaarden, D. O.; Gideon, R. A.  (1982) The
     effects of Mount St. Helens volcanic ash on the pulmonary
     function of 120 elementary school children. Am. Rev. Respir.
     Dis. 126: 1066-1069.

Kalkstein, L.S. (1991)  A new approach to evaluate the impact of
     climate on human mortality.  Environ. Health Perspect. 96:
     145-150.

Katsouyanni, K.; Hatzakis, A.; Kalandidi, A.; Trichopoulos, D.
     (1990a) Short-term effects of atmospheric pollution on
     mortality in Athens. Arch. Hellen. Med. 7: 126-132.

Katsouyanni, K.; Karakatsani, A.; Messari, I.; Touloumi, G.;
     Hatzakis, A.; Kalandidi, A.; Trichopoulos, D.  (1990b) Air
     pollution and cause specific mortality in Athens.
     J. Epidemiol. Commun. Health 44: 321-324.

Katsouyanni, K.; Pantazopoulou, A.; Touloumi, G.; Tselepidaki,
     I.; Moustris, K.; Asimakopoulos, D.; Poulopoulou, G.;
     Trichopoulos, D. (1993) Evidence for interaction between air
     pollution and high temperature in the causation of excess
     mortality. Arch. Environ. Health 48: 235-242.

Kenny, R.A., ed. (1989)  Physiology of aging.  St. Louis, MO:
     Mosby-Year Book, Inc.

Kim, C.S.; Lewars, G.A.; Sackner, M.A.  (1988).  Measurement of
     total lung aerosol deposition as an index of lung
     abnormality.  J. Appl. Physiol. 64:1527-1536.

Kinney, P. L.; Ito, K.; Thurston, G. D.  (1995) A sensitivity
     analysis of mortality/PM10 associations in Los Angeles.
     Inhalation Toxicol. 7: 59-69.
-------
                                12

Kinney, P- L.; Ozkaynak, H.  (1991) Associations of daily
     mortality and air pollution  in Los Angeles County. Environ.
     Res. 54: 99-120.

Kleinman, M.T.; Bhalla, O.K.; Mautz, W.J.; Phalen, R.F.  (1995)
     Cellular and Immunologic Injury with PM-10 Inhalation.
     Inhalation Toxicol. 7:  589-602.

Kodavanti et al., 1995

Koenig, J. Q.; Dumler, K.; Rebolledo, V.; Williams,  P. V.;
     Pierson, W. E.  (1993) Respiratory effects of  inhaled
     sulfuric acid on senior asthmatics and  nonasthmatics. Arch.
     Environ. Health 48: 171-175.

Koening, J.Q.; Covert, D.S.; Pierson, W.E.  (1989)  Effects of
     inhalation of acidic compounds on pulmonary function in
     allergic adolescent subjects.  In: Symposium  on the health
     effects of acid aerosols; October 1987; Research Triangle
     Park, NC.  Environ. Health Perspect. 79:173-178.

Koutrakis, P.; Briggs, S.L.K.; Leaderer, B.P.  (1992)  Source
     apportionment of indoor aerosols in Suffolk and Onondaga
     Counties, NY.  Environ. Sci. Technol. 26:521-527.

Lawther, P.J.  (1973)  Compliance  with the Clean Air  Act: Medical
     Aspects.  J. of the Instit.  of Fuel:Volume XXXVI, No.
     271:341-344.

Lawther, P- J.; Waller, R. E.; Henderson, M.  (1970)  Air pollution
     and exacerbations of bronchitis. Thorax 25: 525-539.

Li,  Y.; Roth, H.D.  (1995).   Daily Mortality  analysis by using
     different regression models  in Philadelphia County, 1973-
     1990.  Inhalation Toxicol 7:45-58.

Ligocki, M. P.; Salmon. L. G.; Fall, T.; Jones, M. C. ; Nazaroff,
     W. W.; Cass G. R.  (1993) Characteristics of airborne
     particles inside southern California museums.   Atmos.
     Environ. Part A 27: 697-711.

Linn,  W.S.; Shamoo, D.A.; Anderson, K.R.; Peng, R.C.; Avol,  E.L.;
     Hackney, J.D.  (1994)  Effects of prolonged, repeated
     exposure to ozone, sulfuric  acid, and their combination on
     healthy and asthmatic volunteers.  Am.  J. Respir. Crit  Care
     Med.  150:431-440.

Lioy,  P.J.  (1990)  Assessing total human exposure  to
     contaminants.  Environ. Sci. Technol. 24: 938-945.
-------
                                13

Lioy, P.J.; Waldman, J.M.; Buckley.- T.; Butler, J.; Pietarinen,
     C. (1990)  The personal, indoor and outdoor concentrations
     of PM-10 measured in an industrial community during the
     winter.  Atmos. Environ. Part B 24: 57-66.

Lipfert, F. W. (1994a) Air Pollution and Community Health - a
     Critical Review and Data Source book.  Chapter 5 - The Air
     Pollution Disasters. New York, NY: Van Nostrand Reinhold.
     Pgs. 111-142.

Lipfert, F. W. (1994b) Application of spatial filtering
     techniques to cross-sectional analysis of air
     pollution-mortality relationships. Am. J. Respir. Crit. Care
     Med. 149: A661.

Lipfert, F. W. (1994c) A simulation study of the effect of
     measurement error on the determination of empirical
     dose-response functions [draft]. Palo Alto, CA: Electric
     Power Research Institute

Lipfert, F. W. (1994d) Filter artifacts associated with
     particulate measurements: recent evidence and effects on
     statistical relationships. Atmos. Environ. 28: 3233-3249.

Lipfert, F. W. (1993) Community air pollution and mortality:
     analysis of 1980 data from US metropolitan areas. I.
     Particulate air pollution. Upton, NY:  U.S. Department of
     Energy, Brookhaven National Laboratory; report no. BNL
     48446-R.

Lipfert, F. W. (1984) Air pollution and mortality: specification
     searches using SMSA-based data. J. Environ. Econ. Manage.
     11: 208-243.

Lipfert, F. W.; Malone, R. G.; Daum, M. L.; Mendell, N. R.; Yang,
     C.-C.  (1988) A statistical study of the macroepidemiology of
     air pollution and total mortality. Upton, NY: Brookhaven
     National Laboratory; report no. BNL-52122.

Lippmann, M.  (1989a) Progress, prospects, and research needs on
     the health effects of acid aerosols. In: Symposium on the
     health effects of acid aerosols; October 1987; Research
     Triangle Park, NC. Environ. Health Perspect. 79: 203-205.

Lippmann, M.  (1989b)  Background on health effects of acid
     aerosols.  Environ. Health Perspect. 79:3-6.

Lippman, M.; Schlesinger, R.B.; Leikanf, G.; Spektor, D.; Albert,
     R.E. (1981).  Effects of sulfuric acid aerosols on
     respiratory tract airways. Inhaled Particles V.
-------
                                14

Lippmann, M.; Thurston, G.D. (in press).  Sulfate concentrations
     as an indicator of ambient particulate matter air pollution
     for health risk evaluations.  Prepared for The Annual
     Conference of the International Society for Environmental
     Epidemiology and the International Society of Exposure
     Analysis, Noordwijkerhout, The Netherlands.

Lowe, D.O.  (1993)  Laboratory investigation of pre-thrombotic
     states.  In: Potter, L.; Thompson, J.M.; eds.  Thrombosis
     and its management.  Edinburgh: Churchill Livingstone,  31-
     46.

Lunn, J. E.; Knowelden, J.; Handyside, A. J. (1967) Patterns of
     respiratory illness in Sheffield infant schoolchildren. Br.
     J. Prev. Soc. Med. 21: 7-16.

MacNee, W.; Selby, C.  (1993)  Neutrophil traffic in the lungs:
     role of haemodynamics, cell adhesion, and deformability.
     Thorax; 48:79-88.

Martin, A. E. (1964) Mortality and morbidity statistics and  air
     pollution.  Proc. R. Soc. Med. 57: 969-975.

Martin, A. E.; Bradley, W. H. (1960) Mortality, fog and
     atmospheric pollution: an investigation during the winter of
     1958-59. Mon. Bull. Minist. Health Public Health Lab. Serv.
     (GB) 19: 56-73.

MathTech, Inc.(1983)  Benefit and net benefit analysis of
     alternative national ambient air quality standards for
     particulate matter (Volume III).  Prepared for the U.S. EPA,
     Office of Air Quality Planning and Standards, Research
     Triangle Park, NC. January 1983.

Mauderly, J, L.; Snipes, M. B. ; Barr, E. B.; Belinsky, S. A.;
     Bond, J. A.; Brooks, A. L.; Chang, I.-Y.; Cheng, Y. S.;
     Gillett, N. A.; Griffith, W. C.; Henderson, R. F.; Mitchell,
     C. E.; Nikula, K. J.; Thomassen, D. G. (1994) Pulmonary
     toxicity of inhaled diesel exhaust and carbon black in
     chronically exposed rats. Part I: neoplastic and
     nonneoplastic lung lesions. Cambridge, MA: Health Effects
     Institute;  research report no. 68.

Mazumdar, S.; Schimmel, H.; Higgins, I. (1981) Daily mortality,
     smoke and SO2 in London,  England 1959 to  1972.  In:
     Frederick,  E. R., ed. A specialty conference on: the
     proposed SOX and particulate standard;  September 1980;
     Atlanta, GA. Pittsburgh, PA: Air Pollution Control
     Association; pp. 219-239.
-------
                                15

Mazumdar, S. and N. Sussman  (1981).  Relationships of air
     pollution to health:  results from the Pittsburgh study.
     Proceedings of the 74th Annual Meeting, Air Pollution
     Control Association, Philadelphia, PA.  June 21-26, 1981.

McFarland, A.R.; Ortiz, C.A.; Rodes, C.E.  (1981).  Wind tunnel
     evaluation of British smoke  shade sampler.  Atmos. Environ.

McFarland, A.R. (1979).  Wind tunnel evaluation of British smoke
     shade sampler.  EPA Contract No. 68-02-2720.  Air Quality
     Laboratory Report 3565/05/79 ARM.  Civil Engineering
     Department, Texas A&M University.

McKinney, N.; Hermance, H. W. (1967) Stress corrosion cracking
     rates of a nickel-brass alloy under applied potential.  In:
     Stress corrosion testing:  a symposium presented at the
     sixty-ninth annual meting of the American Society for
     Testing and Materials; June-July 1966; Atlantic City, NJ.
     Philadelphia, PA:  American  Society for Testing and
     Materials; pp. 274-291.  (ASTM special technical publication
     no. 425).

Middleton, P.  (1993) Brown Cloud  II:  The Denver Air Quality
     Modeling Study, Final Summary Report.  Metro Denver Brown
     Cloud Study, Inc.  Denver, CO.

Miller, F.J.; Anjiluel, S.; Menache, M.G.; Asgharin, B.; Gerrity,
     T.R. (1995)  Dosimetric considerations relating to
     particulate toxicity. Inhalation Toxicology 7:615-632.

Miller, F.J.; Gardner, D.E.; Graham, J.A.; Lee, R.E.; Wilson,
     W.E.; Bachmann, J.D.  Size considerations for establishing a
     standard for inhalable particles.  J. of the Air Pollution
     Control Association, June 1979; Vol. 29, 6:610-615.

Ministry of Health - London - Her Majesty's Stationary Office
     (1954).  Reports on Public Health and Medical Subjects No.
     95 Mortality and Morbidity During the London Fog. December
     1992. Pages 1-60.

Moolgavkar, S. H.; Luebeck, E. G.; Hall, T. A.; Anderson, E. L.
     (1995a) Particulate air pollution, sulfur dioxide, and daily
     mortality: a reanalysis of the Steubenville data. Inhalation
     Toxicol. 7: 35-44.

Moolgavkar, S. H.; Luebeck, E. G.; Hall, T. A.; Anderson, E. L.
     (1995b) Air pollution and daily mortality in Philadelphia.
     J. Exposure Anal. Environ. Epidemiol.: submitted

Morgan, W. K. C. (1978) Magnetite pneumoconiosis. J. Occup. Med.
     20: 762-763.
-------
                                16

Mueller, P. K.; Hidy, G. M. (1983)  The sulfate regional
     experiment (SURE): report of findings. Palo Alto, CA:
     Electric Power Research Institute; EPRI report no. EA-1901.
     3v.

National Academy of Sciences.  Controlling Airborne Particles.
     University Press, Baltimore, MD.

National Academy of Sciences.  Epidemiology and Air Pollution.
     Available from: National Academy Press, 2101 Constitution
     Ave., NW, Washington, DC  20418.

National Acid Precipitation Assessment Program (NAPAP), (1991).
     Office of the Director, Acid Deposition: State of Science
     and Technology.  Report 24, Visibility: Existing and
     Historical Conditions - Causes and Effects.  Washington,
     D.C.

National Center for Health Statistics; Vital and Health
     Statistics:  Current Estimates from the National Health
     Interview Survey, 1993 (DHHS Publication No. (PHS) 95-1518;
     December 1994.

National Research Council, Committee on Haze in National Parks
     and Wilderness Areas  (1993) Protecting Visibility in
     National Parks and Wilderness Areas.  National Academy
     Press, Washington, D.C.

National Toxicology Program (1992).  Toxicology and
     Carcinogenisis Studies of Talc in f344/N rats and B6C3f,
     mice  (inhalation studies) NTP TR 421 NIH Publications No.
     92-3152.U.S. Department of Health and Human Services.

Neas, L.M.; Dockery, D.W.; Koutrakis, P.; Tollerud,  D.J.;
     Speizer, F.E. (1995)  The association of ambient air
     pollution with twice daily peak expiratory flow rate
     measurements in children.  Am. J. Epidemiol. 141:111-122.

Neas, L.M.; Dockery, D.W,; Ware, J.H.; Spengler, J.D.; Ferris,
     B.C., Jr.; Speizer, F.E. (1994) Concentration of indoor
     particulate matter as a determinant of respiratory health in
     children. Am. J. Epidemiol. 139: 1088-1099.

Niinimaa, V.; Cole, P.; Mintz, S.;  Shephard, R.J. (1980)  The
     switching point from nasal to oronasal breathing.  Respir.
     Physiol. 42: 61-71.

Nriagu, J.O.  (1978)  Deteriorative effects of sulfur pollution on
     materials.  In: Nriagu, J.O.,  ed. Sulfur in the environment,
     part II: ecological impacts.  New York, NY: John Wiley &
     Sons; pp. 1-59.
-------
                                17

Oberdorster, G.; Gelein, R.; Ferin, J.; Weiss, B.  (1995a)
     Association of particulate air pollution and acute
     mortality: involvement of ultrafine particles? In:
     Colloquium on particulate air pollution and human mortality
     and morbidity; January; Irvine, CA. Inhalation Toxicol. 7:
     111-124.

Oberdorster et al. (1995b) (Abstract).Am. J. Respir. Crit. Care
     Ned.: in press.

OberdSrster et al. (1995c) (Abstract). In: Advances in combustion
     toxicology: proceedings of an international colloquium;
     Oklahoma City, OK.

Oberdorster, G.; Ferin, J.; Gelein, R.; Soderholm, S. C.;
     Finkelstein, J. (1992) Role of the alveolar macrophage in
     lung injury: studies with ultrafine particles. Environ.
     Health Perspect. 97: 193-199.

Ostro, B. (1993) The association of air pollution and mortality:
     examining the case for inference. Arch. Environ. Health 48:
     336-342.

Ostro, B. D. (1987) Air pollution and morbidity revisited: a
     specification test. J- Environ. Econ. Manage. 14: 87-98.

Ostro, B. D. (1983) The effects of air pollution on work loss and
     morbidity. J. Environ. Econ. Manage. 10: 371-382.

Ostro, B. D.; Sanchez, J. M.; Aranda, C.; Eskeland, G. S.  (1995a)
     Air pollution and mortality: results of a study of Santiago,
     Chile. J. Exposure Anal. Environ. -Epidemiol.: submitted.

Ostro, B. D.; Lipsett, M. J.; Mann, J. K.; Braxton-Owens, H.;
     White, M. C.  (1995b) Air pollution and asthma exacerbations
     among African-American children in Los Angeles. Inhalation
     Toxicol.: in press.

Ostro, B.D.; Lipsett, M.J.; Mann, J.K.; Krupnick, A.; Harrington,
     W.  (1993)  Air pollution and respiratory morbidity among
     adults in Southern California.  Am. J. of Epidem. 137: p.
     691.

Ostro, B. D.; Lipsett, M. J.; Wiener, M. B.; Seiner, J. C.  (1991)
     Asthmatic responses to airborne acid aerosols. Am. J. Public
     Health 81: 694-702.

Ostro, B. D.; Rothschild, S. (1989) Air pollution and acute
     respiratory morbidity: an observational study of multiple
     pollutants. Environ. Res. 50: 238-247.
-------
                                18

Ottaway, C.A.; Warren, R.E.; Saibil, F.G.; et al.  (1984)
     Monocyte procoagulant activity in Whipple's disease.  J-
     Clin. Immunol. 4:348-58.

Ozkaynak, H.; Xue, J.; Severance, P.; Burnett, R.; Raizenne, M.
     (1994) Associations between  daily mortality,  ozone,  and
     particulate air pollution in Toronto, Canada. Presented at:
     Colloquim on particulate air pollution and human mortality
     and morbidity; January; Irvine, CA.  Irvine,  CA: University
     of California at Irvine, Air Pollution Health Effects
     Laboratory; report no. 94-02.

Ozkaynak, H.; Thurston, G. D. (1987) Associations  between 1980
     U.S. mortality rates and alternative measures of airborne
     particle concentration. Risk Anal. 7: 449-461.

Penna, M. L. F.; Duchiade, M. P.  (1991) Contaminacion del aire y
     mortalidad infantil por neumonla [Air pollution and  infant
     mortality due to pneumonia]. Bol. Of. Sanit.  Panam.  110:
     199-207.

Perry, G.B.; Chai, H.; Dickey, D.W.; Jones, R.H.;  Kinsman, R.A.;
     Morrill, C.G.; Spector, S.L.; Weiser, R.C. (1983)  Effects
     of particulate air pollution on asthmatics. Am. J. Public
     Health 73: 50-56.

Pitchford, M.; Malm, W. (1994) Development and Applications of a
     Standard Visual Index.  Atmospheric  Environment, vol. 28,
     no. 5, pp. 1049-1054.

Pope, C. A., III.  (1991) Respiratory hospital admissions
     associated with PMj0 pollution in Utah, Salt Lake, and Cache
     Valleys. Arch. Environ. Health 46: 90-97.

Pope, C. A., Ill; Dockery, D. W.; Schwartz, J. (1995) Review of
     epidemiological evidence of  health effects of particulate
     air pollution. Inhalation Toxicol, 7: 1-18.

Pope, C. A., Ill; Kalkstein, L. S. (1995) Synoptic weather
     modeling and estimates of the exposure-response relationship
     between daily mortality and  particulate air pollution.

Pope, C. A., Ill; Thun, M. J.; Namboodiri, M. M.;  Dockery, D. W.;
     Evans, J. S.; Speizer, F. E.; Heath, C. W., Jr. (1995)
     Particulate air pollution as a predictor of mortality in a
     prospective study of U.S. adults. Am. J. Respir. Grit. Care
     Med. 151: 669-674.
-------
                                19

Pope, C. A., Ill; Kanner, R. E.  (1993) Acute effects of PM10
     pollution on pulmonary function of smokers with mild to
     moderate chronic obstructive pulmonary disease. Am. Rev.
     Respir. Dis. 147: 1336-1340.

Pope, C. A., Ill; Schwartz, J.; Ransom, M. R. (1992) Daily
     mortality and PM,0 pollution in Utah valley. Arch. Environ.
     Health 47: 211-217-

Pope, C. A., III.; Dockery, D. W. (1992) Acute health effects of
     PM10 pollution on symptomatic and asymptomatic children. Am.
     Rev. Respir. Dis. 145: 1123-1128.

Pope, C. A., Ill; Dockery, D. W.; Spengler, J. D.; Raizenne, M.
     E. (1991) Respiratory health and PM10 pollution: a daily time
     series analysis. Am. Rev. Respir. Dis. 144: 668-674.

Pope, C. A., Ill  (1989).  Respiratory Disease Associated with
     Community Air Pollution and a Steel Mill, Utah Valley.  Am.
     J. Public Health 79:623-628.

Quackenboss, J. J.; Krzyzanowski, M.; Lebowitz,  M. D. (1991)
     Exposure assessment approaches to evaluate respiratory
     health effects of particulate matter and nitrogen dioxide.
     J. Exposure Anal. Environ. Epidemiol. 1: 83-107.

Ransom, M. R.; Pope, C. A., III.  (1992) Elementary school
     absences and PM10 pollution  in Utah Valley.  Environ. Res. 58:
     204-219.

Roemer, W.; Hoek, G.; Brunekreef, B.  (1993) Effect of ambient
     winter air pollution on respiratory health of children with
     chronic respiratory symptoms. Am. Rev. Respir. Dis. 147:
     118-124.

Robinson, J.; Nelson, W.C.  (1995)  National human activity
     pattern survey database.  Research Triangle Park, NC: U.S.
     Environmental Protection Agency.

Russell, C.A. (1976) How environmental pollutants diminish
     contact reliability.  Insul. Circuits 22: 43-46.

Saldiva, P.H.N.; Pope, C.A., III; Schwartz, J.; Dockery, D.W.;
     Lichtenfels, A.J.; Salge, J.M.; Barone, I.; Bohm, G.M.
     (1995).  Air Pollution and Mortality in Elderly People: A
     Time-Series Study in Sao Paulo, Brazil. Arch, of Environ.
     Health 50:159-163.
-------
                                20

Samet, J.M.; Zeger, S.L.; Berhane, K. (1995). The Association of
     Mortality and Particulate Air Pollution, in:  Particulate
     Air Pollution and Daily Mortality:  Replication and
     Validation of Selected Studies.  Prepared by:  Health
     Effects Institute, 141 Portland Street, Suite 7300,
     Cambridge, MA 02139.  August 1995.

Samet, J. M.; Tager, I. B.; Speizer, F. E.  (1983) The
     relationship between respiratory illness in childhood and
     chronic air-flow obstruction in adulthood. Am. Rev. Respir.
     Dis. 127: 508-523.

Samet, J.M.; Speizer, F.E.; Bishop, J.D.; Spengler, J.D.; Ferris,
     B.J. (1981).  The relationship between air pollution and
     emergency room visits in an industrial community.  J. Air
     Pollut. Control Assoc. 31:236-240.

Sanyal, B.; Singhania, G.K. (1956) Atmospheric corrosion of
     metals; part I.J. Sex. Ind. Res. Sect. B 15: 448-455.

Schimmel, H. (1978) Evidence for possible acute health effects of
     ambient air pollution from time series analysis:
     methodological questions and some new results based on New
     York City daily mortality, 1963-1976. Bull. N. Y. Acad. Med.
     54: 1052-1108.

Schimmel, H., and T.J. Murawski (1976).  The relation of air
     pollution to mortality-  J. Occup. Med. 18:316-333.

Schwartz, H. (1972)  On the effect of magnetite on atmospheric
     rust and on rust under a coat of paint.  Werkst. Korros. 23:
     648-663.

Schwartz, J. (in press). Short term fluctuations in air pollution
     and hospital admissions of the elderly for respiratory
     disease. Thorax.

Schwartz, J. (in press),  Air pollution and hospital admissions
     for respiratory disease. Epidemiology 7:

Schwartz, J. (1995b) Health effects of air pollution from
     traffic: ozone and particulate matter. In: Fletcher, T., ed.
     Health at the crossroads: transportation policy and urban
     health, proceedings of the fifth annual public health forum
     of the London School of Hygiene and Tropical Medicine;
     April; London, United Kingdom. New York, NY: John Wiley &
     Sons, Inc.; in preparation.

Schwartz, J. (1994a) Total suspended particulate matter and daily
     mortality in Cincinnati, Ohio. Environ. Health Perspect.
     102: 186-189.
-------
                                21

Schwartz, J. (1994b) Air pollution and daily mortality: a review
     and meta analysis. Environ. Res. 64: 36-52.

Schwartz, J. (1994c) What are people dying of on high air
     pollution days? Environ. Res.  64: 26-35.

Schwartz, J. (1994d) Air pollution and hospital admissions for
     the elderly in Detroit, Michigan. Am. J. Respir. Crit. Care
     Med. 150: 648-655.

Schwartz, J. (1994e) Air pollution and hospital admissions for
     the elderly in Birmingham, Alabama. Am. J. Epidemiol. 139:
     589-598.

Schwartz, J. (1994f) PMIO, ozone, and hospital admissions for the
     elderly in Minneapolis, MN. Arch. Environ. Health 49:
     366-374.

Schwartz, J. (1994g) Nonparametric smoothing in the analysis of
     air pollution and respiratory illness. Can. J. Stat. 22:
     1-17.

Schwartz, J. (1994h) The use of generalized additive models in
     epidemiology. Proc. Int. Conf. Biometric Soc. 17: 55-80.

Schwartz, J. (1993a) Air pollution and daily mortality in
     Birmingham, Alabama. Am. J. Epidemiol. 137: 1136-1147.

Schwartz, J. (1993b) Particulate air pollution and chronic
     respiratory disease. Environ.  Res. 62: 7-13.

Schwartz, J.; Morris, R. (in press) Air pollution and
     cardiovascular hospital admissions. Am. J. Epidemiol.

Schwartz, J.; Dockery, D. W.; Neas, L. M. (in press).  Is Daily
     Mortality Associated Specifically with Fine Particles?
     Report to EPA from Environmental Epidemiology Program,
     Harvard School of Public Health, 665 Huntington Ave.,
     Boston, MA 02115.

Schwartz, J.; Dockery, D.W.; Neas,  L.M.; Wypij, D.; Ware, J.H.;
     Spengler, J.D.; Koutrakis, P.; Speizer, F.E.; Ferris, B.C.,
     Jr. (1994)  Acute effects of summer air pollution on
     respiratory symptom reporting in children.  Am. J. Respir.
     Crit. Care Med". 150: 1234-1242.

Schwartz, J.; Slater, D.; Larson, T. V.; Pierson, W. E.; Koenig,
     J.  Q. (1993) Particulate air pollution and hospital
     emergency room visits for asthma in Seattle. Am. Rev.
     Respir. Dis. 147: 826-831.
-------
                                22

Schwartz, J.; Dockery, D. W. (1992a) Increased mortality in
     Philadelphia associated with daily air pollution
     concentrations. Am. Rev- Respir. Dis. 145: 600-604.

Schwartz, J.; Dockery, D. W. (1992b) Particulate air pollution
     and daily mortality in Steubenville, Ohio. Am. J. Epidemiol.
     135: 12-19.

Schwartz, J.; Spix, C.; Wichmann, H. E.; Malin, E.  (1991) Air
     pollution and acute respiratory illness in five German
     communities. Environ. Res. 56: 1-14.

Schwartz, L.W.; Moore, P.P.; Chang, D.P-; Tarkmyton, B.K.;
     Dungworth, D.L.; Tyler, W.S. (1977)  Short-term effects of
     sulfuric acid aerosols on the respiratory tract.  A
     morphological study in guinea pigs, mice, rats, and monkeys.
     In: Lee, S.D., ed. Biochemical effects of environmental
     pollutants.  Ann Arbor, MI: Ann Arbor Science Publishers,
     Inc.; pp. 257-271.

Seaton, A.; MacNee, W.; Donaldson, K.; Godden, D.  (1995)
     Particulate air pollution and acute health effects. Lancet
     (8943): 176-178.

Shumway, R. H. (1988) Applied statistical time series analysis.
     Englewood Cliffs, NJ: Prentice Hall, Inc.

Shumway, R. H.; Azari, A. S.; Pawitan, Y. (1988) Modeling
     mortality fluctuations in Los Angeles as functions of
     pollution and weather effects. Environ. Res. 45: 224-241.

Sinclair, J.D. (1992) The relevance of particle contamination to
     corrosion of electronics in processing and field
     environments. Proc. Electrochem. Soc. 93-1:  325-335.

Sioutas, C.; Koutrakis, P.; Burton, R.M.  (1995)  A technique to
     expose animals to concentrated fine ambient aerosols.
     Environmental Health Perspectives 103:172-177.

Sisler, J.; Malm, W.  (1994)  The Relative Importance of Soluble
     Aerosols to Spatial and Seasonal Trends of Impaired
     Visibility in the United States. Atmospheric Environment.
     vol. 28, no. 5, pp. 851-862.

Sisler, J.; Huffman, D.; Latimer, D, (1993)   Spatial and Temporal
     Patterns and the Chemical Composition of the Haze in the
     United States:  An Analysis of Data from the IMPROVE
     Network, 1988-1991, Fort Collins, CO, 1993.
-------
                                23

Skerry, B.S.; Johnson, J.B.; Wood, G.C. (1988a) Corrosion in
     smoke, hydrocarbon, and SO2 polluted  atmospheres	I.
     General behaviour of iron.  Corros. Sci. 28:  657-695.

Skerry, B.S.; Wood, J.C.; Johnson, J.B.; Wood, G.C.  (1988b)
     Corrosion in smoke, hydrocarbon, and SO2 polluted
     atmospheres	II. Mechanistic implications for  iron from
     surface analytical and allied techniques.  Corros. Sci. 28:
     697-719.

Skornick and Brain (1983)

Spengler, J.D.; Dockery, D.W.; Turner, W.A.; Wolfson, J.M.;
     Ferris, E.G., Jr. (1981)  Long-term measurements of
     respirable sulfates and particles inside and outside homes.
     Atmos. Environ. 15:23-30.

Spence, J. W.; Haynie, F. H. (1974) Design of a laboratory
     experiment to identify the effects of environmental
     pollutants on materials.  In:  Corrosion in natural
     environments.  Philadelphia PA:  American Society for
     Testing and Materials;  ASTM special technical publication
     no.  558; p. 279-291.

Spengler (AQ) personal communication, 1995.

Spix, C.; Heinrich, J.; Dockery, D.; Schwartz, J.; Volksch, G.;
     Schwinkowski, K.; Collen, C.; Wichmann, H. E. (1993)  Air
     pollution and daily mortality in Erfurt, East Germany,
     1980-1989. Environ. Health Perspect.  101: 518-526.

Stern, B. R.; Raizenne, M. E.; Burnett, R. T.; Jones, L.;
     Kearney, J.; Franklin, C. A.  (1994) Air pollution and
     childhood respiratory health: exposure to sulfate and ozone
     in 10 Canadian rural communities. Environ. Res. 66: 125-142.

Stober, W.; Mauderly, J.L.:  (1994)  Model-inferred hypothesis of
     a critical dose for overload tumor reduction by diesel soot
     and carbon black.  Inhalation Toxicology, 6:427-457.

Stringer, B.K.; Imrich, A.; Kobzik, L. (1995)  Lung  epithelial
     cell (A549) uptake of imopsonized environmental particles.
     Am. J. Respiratory Cr. Care Med. 151:A264.

Studnicka, M.J.; Frischer, T.; Meinert, R.; Studnicka-Benke, A.;
     Hajek, K.; Spengler, J.D.; Neumann, M.G.  (1995)  Acidic
     particles and lung function in children:  a summer camp
     study in the Austrian Alps. Am. J. Respir. Crit. Care Med.
     151: 423-430.
-------
                                24

Styer, P-; McMillan, N.; Gao, F.; Davis, J.; Sacks, J.  (1995) The
     effect of airborne particulate matter on daily death counts.
     Environ. Health Perspect.: accepted.

Suh, H.H.; Koutrakis, P.; Spengler, J.D.  The relationship
     between airborne acidity and ammonia in indoor environments.
     J. Expos. Assess. Environ. Epidemiology 1994; 4:1-23.

Sunyer, J.; Saez, M.; Murillo, C.; Castellsague, J.; Martinez,
     F.; Ant6, J. M. (1993) Air pollution and emergency room
     admissions for chronic obstructive pulmonary disease:
     a 5-year study. Am. J. Epidemiol. 137: 701-705.

Sydberger, T.; Ericsson, R.  (1977) Laboratory testing of the
     atmospheric corrosion of steel.  Werkst. Korros. 28: 154-
     158.

Systems Applications International.  Statistical Support for the
     Particulate Matter NAAQS.  Prepared by Systems Applications
     International, 101 Lucas Valley Road, San Rafael, CA 94903.
     July 1995

Tepper, J. S.; Lehmann, J. R.; Winsett, D. W.; Costa, D. L. ;
     Ghio, A. J. (1994) The role of surface-complexed iron  in the
     development of acute lung inflammation and airway
     hyperresponsiveness. Am. Rev. Respir. Dis. 149(4, pt.  2):
     A839.

Thurston, G. D.; Gorczynski, J. E., Jr.; Currie, J. H.; He, D.;
     Ito, K.; Hipfner, J.; Waldman, J.; Lioy, P- J.; Lippmann, M.
      (1994a) The nature and origins of acid summer haze air
     pollution in metropolitan Toronto, Ontario. Environ. Res.
     65: 254-270.

Thurston, G. D.; Ito, K.; Hayes, C. G.; Bates, D. V.; Lippmann,
     M.  (1994b) Respiratory hospital admissions and summertime
     haze air pollution in Toronto, Ontario: consideration  of the
     role of acid aerosols. Environ. Res. 65: 271-290.

Thurston, G. D.; Ito, K.; Kinney, P. L.; Lippmann, M. (1992) A
     multi-year study of air pollution and respiratory hospital
     admissions in three New York State metropolitan areas:
     results for 1988 and 1989 summers. J. Exposure Anal.
     Environ. Epidemiol. 2: 429-450.

Thurston, G. D.; Ito, K.; Lippmann, M.; Hayes, C. (1989)
     Mortality in relation to exposure to acidic aerosols during
     1963-1972 winters. Environ. Health Perspect. 79: 73-82.
-------
                                25

Touloumi, G.; Pocock, S. J.; Katsouyanni, K.; Trichopoulos, D.
     (1994) Short-term effects of air pollution on daily
     mortality in Athens: a time-series analysis. Int. J.
     Epidemiol. 23: 1-11.

U.S. Department of Health, Education, and Welfare. (1964) Smoking
     and health: report of the Advisory Committee to the Surgeon
     General of the Public Health Service. Washington, DC: Public
     Health Service; p. 60.

U.S. Environmental Protection Agency (1995).  Ambient levels and
     noncancer health effects of inhaled crystalline al a
     morphons silica.  Research Triangle Park, NC: National
     Center for Environmental Assessment.  Office of Research and
     Development.  EPA report no. EPA 600/R-95/115.  Final draft.

U.S. Environmental Protection Agency (1994a).  National Air
     Quality and Emissions Trends Report, 1993.  Office of Air
     Quality Planning and Standards. EPA454/R-94-026.  October
     1994.

U.S. Environmental Protection Agency (1994b).  Review of the
     Ambient Air Quality Standards for Sulfur Oxides:  Updated
     Assessment of Scientific and Technical Information,
     Supplement to the 1986 OAQPS Staff Paper Addendum, Office of
     Air Quality Planning and Standards, Research Triangle Park,
     NC, EPA/452/R-94-013.

U.S. Environmental Protection Agency (1994c).  Review of the
     Ambient Air Quality Standards for Sulfur Oxides:  Assessment
     of Scientific and Technical Information, Supplement to the
     1986 OAQPS Staff Paper Addendum, Office of Air Quality
     Planning and Standards, Research Triangle Park,  NC,
     EPA/452/R-94-013.

U.S. Environmental Protection Agency, Office of Air Quality
     Planning and Standards (1993)  Effects of the 1990 Clean Air
     Act Amendments on Visibility in Class I Areas:  An EPA
     Report to Congress.  Research Triangle Park, N.C.

U.S. Environmental Protection Agency (1989).  An acid aerosols
     issue paper:  health effects and aerometrics.  Research
     Triangle Park, NC: Office of Health and Environmental
     Assessment, Environmental Criteria and Assessment Office;
     EPA report no. EPA-600/8-88-005F.  Available from: NTIS,
     Springfield, VA; PB91-25864.

U.S. Environmental Protection Agency (1988).  Report of the Clean
     Air Scientific Advisory Committee  (CASAC) - Recommendations
     for Future Research on Acid Aerosols.  Office of the
     Administrator, Science Advisory Board.  EPA report no: EPA-
     SAB/CASAC-89-002.
-------
                                26

U.S. Environmental Protection Agency. (I986a) Second addendum to
     air quality criteria for particulate matter and sulfur
     oxides (1982): assessment of newly available health effects
     information. Research Triangle Park, NC: Office of Health
     and Environmental Assessment,  Environmental Criteria and
     Assessment Office; EPA report no. EPA-600/8-86-020F.
     Available from: NTIS, Springfield,  VA; PB87-176574.

U.S. Environmental Protection Agency. (1986b) Review of the
     national ambient air quality standards for particulate
     matter: updated assessment of scientific and technical
     information, addendum to the 1982 OAQPS staff paper.
     Research Triangle Park, NC: Office of Air Quality Planning
     and Standards, Strategies and Air Standards Division; report
     no. EPA/450/05-86/012. Available from: NTIS, Springfield,
     VA; PB87-176871/XAB.

U.S. Environmental Protection Agency. (1986c) Air quality
     criteria for ozone and other photochemical oxidants.
     Research Triangle Park, NC: Office of Health and
     Environmental Assessment, Environmental Criteria and
     Assessment Office; EPA report nos.  EPA-600/8-84-020aF-eF.
     5v. Available from: NTIS, Springfield, VA; PB87-142949.

U.S. Environmental Protection Agency. (1982a) Air quality
     criteria for particulate matter and sulfur oxides. Research
     Triangle Park, NC: Office of Health and Environmental
     Assessment, Environmental Criteria and Assessment Office;
     EPA report no. EPA-600/8-82-029aF-cF. 3v. Available from:
     NTIS, Springfield, VA; PB84-156777.

U.S. Environmental Protection Agency- (1982b) Review of the
     national ambient air quality standards for particulate
     matter: assessment of scientific and technical information.
     Research Triangle Park, NC: Office of Air Quality Planning
     and Standards, Strategies and Air Standards Division; report
     no. EPA-450/5-82-001. Available from: NTIS, Springfield, VA;
     PB82-177874.

U.S. Environmental Protection Agency, Office of Air Quality
     Planning and Standards (1979)  Protecting Visibility:  An EPA
     Report to Congress.  Research Triangle Park, N.C.

U.S. Environmental Protection Agency.  (1969)  Air Quality
     Criteria for Particulate Matter.  U.S. Government Printing
     Office, Washington, DC.  AP-49.
-------
                                27

Utell, M.J.; Frampton, M.W.; Morrow, P.E. (1993)  Quantitative
     clinical studies with defined exposures atmospheres.  In:
     Gardner, D.E.; Crapo, J.D.; McClellan, R.O., eds. Toxicology
     of the lung.  2nd ed. New York, NY: Raven Press pp. 283-309.
     (Hayes, A.W.; Thomas, J.A.; Gardner, D.E.; eds. Target organ
     toxicology series).

Utell, M.J.; Mariglio, J.A.; Morrow, P.E.; Gibb, F.R.; Speers,
     D.M. (1989)  Effects of inhaled acid aerosols on respiratory
     function:  the role of endogenous ammonia.  J. Aerosol Med.
     2: 141-147.

Utell, M.J.; Morrow, P.E.; Speers, D.M.; Darling, J.; Hyde, R.W.
     (1983)  Airway responses to sulfate and sulfuric acid
     aerosols in asthmatics:  an exposure-response relationship.
     Am. Rev- Respir. Dis. 128:444-450.

Utell, M.J.; Morrow, P.E.; Hyde, R.W.  (1982)  Comparison of
     normal and asthmatic subjects' responses to snephate
     pollutant aerosols.  In: Walton, W.H.; ed. Inhaled particles
     V. proceedings of an international symposium organized by
     the British Occupational Hygiene Society; September 1980;
     Cardiff, Wales. Ann. Occup. Hyg. 26:691-697.

Utell, M. J.; Aquilina, A. T.; Hall, W. J.; Speers, D. M. ;
     Douglas, R. G., Jr.; Gibb, F. R.; Morrow, P. E.; Hyde, R. W.
     (1980)  Development of airway reactivity to nitrates in
     subjects with influenza. Am. Rev. Respir. Dis. 121: 233-241.

Waller, R.E.  (1980).  The assessment of suspended particulates in
     relation to health.  Atmos. Environ. 14:1115-1118.

Walton, J.R.; Johnson, J.B.; Wood, G.C. (1982) Atmospheric
     corrosion initiation by sulphur dioxide and particulate
     matter	I.  Test-Cell apparatus for simulated atmospheric
     corrosion studies.  Br. Corros. J. 17: 59-64.

Ware, J. H.; Ferris, B. G., Jr.; Dockery, D. W.; Spengler, J. D.;
     Stram,  D. O.; Speizer, F. E.  (1986) Effects of ambient
     sulfur oxides and suspended particles on respiratory health
     of preadolescent children. Am. Rev. Respir. Dis. 133:
     834-842.

Ware, J. H.; Dockery, D. W.; Spiro, A., Ill; Speizer, F. E.;
     Ferris, B. G.," Jr. (1984) Passive smoking, gas cooking,  and
     respiratory health of children living in six cities. Am.
     Rev. Respir. Dis. 129: 366-374.
-------
                                28

Ware, J. H.; Thibodeau, L. A.; Speizer, F. E.; Colome,  S.;
     Ferris, B. G., Jr. (1981) Assessment of  the health effects
     of atmospheric sulfur oxides and particulate matter:
     evidence from observational studies. Environ. Health
     Perspect. 41: 255-276.

Watson, J.G.; Chow, J.C.; Rogers, C.F.; Diaz, S. PM,0  and PM25
     Variations in Time and Space.  Report prepared by  Desert
     Research Institute, Reno, Nevada  (DRI Document No.
     4204.1D1). July 12, 1995.

Watson, J.G.; Rogers, C.F.; Chow, J.C.  (1995)  PM,0 +  PM25
     Variations in Time + Space.  DRI Document No. 4204.IF Report
     to U.S. EPA, October 24, 1995.

Watson, W. D.; Jaksch, J. A.  (1982) Air pollution:  household
     soiling and consumer welfare losses. J.  Environ. Econ.
     Manage. 9: 248-262.

Watson, W. D., Jr.; Jaksch, J. A. (1978) Household cleaning  costs
     and air pollution.  Presented at the 71st Annual Meeting,
     Air Pollution Control Association, Houston, Texas,  June 25-
     30.  Paper No. 78-52.3.

Whitby, K.T.; Sverdrup, G.M.  (1980) California aerosols: their
     physical and chemical characteristics.   In: Hidy,  G.M. ;
     Mueller, P.K.; Grosjean, D.; Appel, B.R.; Wesolowski, J.J.,
     eds.  The character and  origins of smog  aerosols:  a digest
     of results from the California Aerosol Characterization
     Experiment (ACHEX).  New York, NY: John  Wiley &  Sons, Inc.;
     pp. 477-517.  (Advances  in environmental science and
     technology: v. 9).

Whitby, K.T.; Charlson, R.E.; Wilson, W.E.; Stevens,  R.K.  (1974)
     The size of suspended particle matter in air.  Science
     (Washington, DC) 183: 1098-1099.

Whitby, K.T.; Husar, R.B.; Liu, B.Y.H.  (1972) The aerosol size
     distribution of Los Angeles smog.  J. Colloid. Interface
     Sci. 39: 177-204.

White and Roth.  Progressive  Lung Injury in Pulmonary Hibrination
     from Monocrotaline,  In: J.O. Cantor, ed. (Handbook of  Am.
     Model of Pulmonary Disease, Vol. 2, Boca Raton,  FL; CRC
     Press, 1989).

Whittemore, A. S.; Korn, E. L. (1980) Asthma  and air  pollution in
     the Los Angeles area. Am. J. Public Health 70: 687-696.
-------
                                29

Willeke, K.; Whitby, K.T.  (1975) Atmospheric aerosols: size
     distribution interpretation.  J. Air Pollut. Control Assoc.
     25: 529-534.

Wilson, W.E.; Burton, R.M.; Koutrakis, P.; Suh, H.H.  (1995).
     Differentiating Fine  and Coarse Particles: Definitions and
     Exposure Relationships Relevant to Epidemiological Studies.

Wolff, G.T.; Collins, D.C.; Rodgers, W.R.; Verma, M.H.;  Wong,
     C.A.  (1990) Spotting  of automotive finishes from the
     interactions between  dry deposition of crustal material and
     wet deposition of sulfate.  J. Air Waste Manage. Assoc.  40:
     1638-1648.

Wyzga, R.  E.; Lipfert, F.  W. (1995) Ozone and daily mortality:
     the ramifications of  uncertainties and interactions and some
     initial regression results. Ozone conference: accepted.

Yocom, J.E.; Grappone, N.  (1976) Effects of power plant emissions
     on materials.  Palo Alto, CA:  Electric Power Research
     Institute: report no. EPRI/EC-139.  Available from NTIS,
     Springfield, VA; PB-257 539.

Yocom, J.E.; Upham, J.B.  (1977)  Effects of economic materials
     and structures.  In:  Air pollution: v. 11, the effects of
     air pollution. 3rd ed. New York, NY: Academic Press, Inc.;
     pp. 93-94.
-------
                 APPENDIX A

Considerations in Selecting Particle Size Cut Point
                for Fine Particles
-------
External Review Draft                          A-l                          Do Not Quote or Cite
November 1995
Appendix A. Considerations in Selecting Particle Size Cut Point for Fine Particles
       An important decision relating to the choice of indicator is the choice of measurement
which in a sense serves as an operational definition of fine particles. The  CD concludes that
the minimum of mass between the fine and coarse modes lies between 1 and 3  jam, and that
the scientific data support a cut point to delineate fine particles in this range. Because of the
overlap of fine and coarse particles in this intermodal region, specific cut points are only an
approximation of fine particles.  Thus, the decision within this range is largely a policy
judgement.  Staff recommend the three primary factors to consider in selecting a cut point are
consistency with health data, potential for intrusion of mass from the other mode, and
availability of monitoring technology. The main policy choice centers on  two options:
PM2 5 and PMj. Although most fine particle (accumulation mode) mass is  below l.Oum,
some hygroscopic particles in conditions of high relative humidity may gain  water and grow
above this size.
       From a public health perspective, PlvL) 5 captures all  of the potential  agents of concern
in the fine fraction.  For example,  Plv^  5 captures most sulfates, acids, fine particle metals,
organics, and ultrafme particles and accounts  for most of surface area, and particle number.
Although the CD outlines some conditions (e.g., relative humidity near 100 percent) under
which it is possible that hygroscpic particles may grow above 2.5^m, PIv^ 5 is  still better
able to capture them than PMi.
       PMo 5 has been used directly in  many health studies  as described in the  CD and
Chapter V above (see Table V-5).  Associations have been reported between exposures to
PM2 5 and mortality, hospital  admissions, cough, upper respiratory infection, lower
respirator}' infection, and asthma status,  and pulmonary function changes (although not all  of
these associations are statistically significant).
       PM"> c measurement technologies are  widely available and have been in  routine use in
the field since the early 1980s. For example, the EPA AIRS database contains PM^ 5 data
from  the Inhalable Particle Network  (1982-1984), the IMPROVE network  (1989-present), and
NESCAUM network (1988- present). In addition, the California Air Resource Board (CARB)
dichotomous sampler network  has  been  collecting PM^ 5 data routinely since 1980, and  many
-------
External Review Draft                         A-2                          Do Not Quote or Cite
November 1995
other special studies using PN^ 5 have been conducted across the country. Furthermore,
dichotomous samplers allow the coincident measurement of PMi Q and PlVk c, increasing the
certainty of comparability between the two measurements.
       PMj, on the other hand, has not been used in health studies primarily due to lack of
available monitoring data. Comparisons between PMj and other measurements that were used
in the health studies (e.g., PM^Q) are also not widely available due to lack of available PMj
monitoring data.  Furthermore, PMj may not capture as much of the hygroscopic substances
such as sulfates.  Health studies report statistically significant associations between sulfate
measurements and endpoints including increased mortality and hospital admissions.
       PMi sampling technologies have been developed and some limited validated data are
available from locations such as Phoenix, Arizona.  However,  the PMi samplers have not
been widely field-tested to date.
       Proponents of the PMj option are concerned that the intrusion of particles generated
by grinding or crushing (i.e., coarse mode particles) into the daily PM9 c measurement could
                                                                 £*» *J
create spurious NAAQS exceedances.  Given the lack of PMj  data  currently available, it is
difficult to determine how much intrusion might occur or what areas might be affected during
the implementation of the PM NAAQS. The available data show that typically only 5-15
percent (on the order of 1 to  5 ug/m ) of the PN^ 5 mass is attributable to soil-type sources
even in dusty areas such as San Joaquin Valley, California, and Phoenix, Arizona.  However,
this percentage may increase during events such as high winds.
       The staff judges that hi typical urban areas, the potential for this type of intrusion may
be smaller, but without sufficient data these determinations remain very uncertain.  A sharper
inlet for the Federal Reference Method may help to minimize the intrusion of coarse mode
particles into the PM2 5 measurement.  Although intrusion of coarse mode particles into daily
PM9 5 measurements is not anticipated to be significant in most situations, if in light of more
data  a problem is identified, this issue might be better addressed on a case-by-case in the
monitoring and implementation programs.
       Finally, the staff concludes that PM2 5 measurements are more appropriate than some
of the measurements historically used in the  epidemiological studies (e.g., BS, CoH) although
-------
External Review Draft                         A-3                          Do Not Quote or Cite
November 1995
these measurements have been useful in advancing the state of scientific knowledge of particle
effects.  British Smoke (BS) reading varies more with darkness of particles  (i.e., carbon
content)  than with mass, making associations with mass highly site- and time-specific.  Using
a similar principle to  BS, the principle of COH is that visible light is transmitted through (or
reflected from as in the case of BS) a section of filter paper before and after ambient air is
drawn through it.  Thus, COH associations with mass are also highly site- and time-specific.
The BS method emphasizes control of primary elemental carbon emissions;  however,
elemental carbon is a minor contributor to fine and total mass in current U.S. atmospheres.
Furthermore, lack of consistent relationships between BS reflectance and PM mass
measurements diminishes one of the major advantages:  BS is not related to the available
quantitative health data from U.S.  cities with as much certainty as  the PVU 5 mass
measurements although BS is used in many other countries.
       Thus, because of the consistency with health  data,  small potential for intrusion, and
availability of monitoring technology and existing air quality database, the staff judges that
the PM2 5 measurement is more appropriate for regulatory purposes than PMj, or historical
measurements such as BS or COH.
-------
                APPENDIX B




Chemical Composition Data for Participate Matter
-------
               PM2.5 COMPOSITION  (24-h AVG)
                                             EASTERN U.S.
               Units g ug/m3
 D
 T1
 I
 O
 O
 Z
 O
 H
O
 C
 O
 H
 m
O
»
n
H— «
H
tn
Ref
Site
Dates
Hours
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Nl
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
TI
V
Zn
1
Smoky Mtns
9/20-26/78
12
12
24.00
222
1.10
0.30
12.00

<0.054
<0.003

0.018
0.016

<0.010

0.003
0.028
0.040






0.097

3.744

0.001
0.038


<0.006
-------
             PM2.5 COMPOSITION  (24-h AVG)     WESTERN U.S.
 Tl
 H

 6
 o

 "Z
 o
 H

O
 C
 O
 H
 m
n
>— i
H
tn
                                                                                    Units as ug/m3
Ref
Site
Dates
Hours
Our
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Ni
P
Pb
Rb
S
Sb
Se
SI
Sn
Sr
Ti
V
Zn
8(a)
Res.Tr.Pk
1980
24
3
28.77





0.073
0.002

0.007
0.035



0.016
0.120
0.148

0.003


0.001
0.042
0.106

2.835

0.002
0.350




0.018
9(g)
Los Angeles
Summer'87
4,5 and 7
11 days
41.10
8.27
2.37
4.34
9.41

0.035
0.022
0.015
0.013
0.022

0.093
0.022
0.063
0.099
0.041
0.024
0.016

0.202
0.005
0.060
0.038

2.832

0.013
0.052

0.019
0.005
0.006
0.090
9(g)
Los Angeles
Fall'87
4 and 6
6 days
90.20
18.46
7.28
22.64
4.38

0.250
0.015
0.043
0.065
0.335

0.453
0.025
0.273
0.557
1 0.217
0.075
0.043

0.466
0.007
0.046
0.185

1.998

0.011
0.520

0.028
0.060
0.007
0.298
10f.)
San Joaquln Valley
6'88-6'89
24
~35
29.89
4.87
3.24
8.17
3.00

0.152

0.012
0.010
0.096
<0.007
0.094
0.003
0.096
0.180
0.188

0.006


0.016
0.007
0.029
0.001
1.242
<0.002
0.001
0.460
<0.015
0.002
0.017
0.015
0.078
110)
Phoenix
10/13/89-1/17/90
6 h, 2x/day
~ 100 days
29.37
10.10
7.47
3.60
1.33

0.130
.<0.020
<0.106
0.011
0.170
<0.018
0.365
0.003
0.015
0.216
0.207

0.023
<0.006

0.003
<0.051
0.039
<0.0025
0.437
<0.033
<0.002
0.430
<0.028

<0.030
<0.016
0.056
5(d)
Boise
12/86-3/87
7am-7pm-7a
12
35.70
12.70
1.70



0.102
0.002

0.014
0.026

0.122
0.001
0.011
0.022
0.145

0.002
0.002



0.045

0.603

0.001
0.069


i
0.001
0.019
12(0
Nevada
11/86-1/87
00-2400
24
24
56.92
19.97
15.17
2.43
1.67

0.275
0.001
0.013
0.033
0.215

0.145
0.002
0.010
0.310
0.280

0.015


0.006
0.041
0.115
0.001
0.765

0.000
0.860

0.004
0.043
0.009
0.033
8(a)
TarrantCA
1980
24
6
57.05





0.177


0.102
0.455


0.002
0.047
0.316
0.186

0.032


0.003

0.619

2.578


0.583


0.010

0.095
8(a)
Five Points C
1980
24
3
31.80





0.239


0.015
0.150

0.004
0.001
0.024
0.216
0.244

0.005


0.025
0.007
0.087

1.129

0.001
0.656


0.005
0.006
0.016
8(a)
Riverside CA
1980
24
4
35.18





0.036


0.037
0.301

0.009

0.040
0.127
0.120

0.007


0.007

0.376

1.653

0.001
0.234



0.003
0.029
References are listed In Table 1 Appendix. Associated notes are explained In Table 1.

Values for this size fraction are calculated from the average measured values reported for the other two size fractions.
                                                                                                                                               w
                                                                                                                                               I
-------
           PM2.5 COMPOSITION  (24-h AVG)
                                                           CENTRAL U.S.
Unite » ug/m3
Ret
Site
Dates
Hours
Dur
Number
Mass
! OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
C!
Cr
Cu
Fe
K
' Mg
Mn
Mo
Na
Ni
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
Ti
V
Zn
8(a)
San Jose CA
1980
24
6
56. 26





0.123
0.001

0.188
0.089

0.050
0.003
0.043
0.148
0.248

0.006


0.006
0.013
0.891

0.852


0.292



0.002
0.061
8(a)
Honolulu
1980
24
1
21.10





1.127


0.017
1.024

0.518
0.004
0.018
0.726
0.371

0.020


0.002
0.002
0.071

0.313


2.363


0.063
0.001
0.011
8(a)
Winnemucca
1980
24
5
9.6T





0.361


0.006
0.243



0.026
0.231
0.149

0.003


0.001

0.042

0.358


0.914


0.009

0.011
8(a)
Portland
1980
24
4
37.15





0.581
0.012

0.093
0.154

0.021
0.009
0.072
0.270
0.218

0.052


0.027
0.017
0.422

1.944

0.001
0.377


0.005
0.014
0.081
8(a)
Seattle
1980
24
1
10.70





0.002
0.006

0.019
0.037


0.002
0.024
0.098
0.080

0.004


0.006
0.006
0.215

0.831

0.001
0.092




0.059
5(d)
Albuquerque
12/84-3/85
7am-7pm-7am
12
20.60
13.20
2.10



0.077


0.085
0.059

0.036


0.045
0.074


0.000



0.237

0.507


0.076




0.007
13
Denver
1/11-30/82
6f\m-6pm-6a
12
~26
26.73
7.11
2.15
2,22
2.06

0.394
<0.002
0.031
0.103
0.047
0.006
0.052
<0.009
0.010
0.079
0.079

0.011


0.003
0.043
0.326
<0.003
0.709


0.277

,<0.003
<0.027

0.046
14(m)
Urban Denver
11/87-1/88
9am-4pm-9am
7&17
~136
19.67
7.25
4.41
3.96
1.55

0.037


0.018
0.056
0.005
0.141
0.003
0.017
0.111
0.077

0.012


0.002

0.075

0.642
0.004
0.001
0.272
0.006
0.001
0.009

0.031
14(aa) 15
Non-urban Denver Chicago
11/87-1/88 7/94
9am-4pm-9am 0800-0800
78,17 24
"150 16
10.35 13.57
5.39
1.31



0.046
<0.003
< 0.091
0.004
0.045
<0.029
0.011
<0.005
0.011
0.089
0.061
0.012
0.005
<0.002
0.022
<0.001
0.008
0.027

1.321
<0.042
<0.001
0.074
<0.049

<0.029
<0.009
0.052
H
tn
  References are listed in Table 1 Appendix. Associated notes are explained in Table 1.

* Values for this size fraction are calculated from the average measured values reported for the other two size fractions.
-------
                  PM2.5 COMPOSITION (24-h AVG)
                                                           CENTRAL U.S.
 O
 O

 2
 O
 H

O
 d
 o
 H
 m
o
H-l
H
m
                                                  Units = ug/m3
Ref
Site
Dates
Hours
Our
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Ni
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
Ti
V
Zn
16
Houston
9/10-19/80
12
20
38.60
5.68
1.42
0.59
14.61

0.123
<0.005
0.048
0.055
0.155
<0.003
0.032
<0.005
0.028
0.162
0.119

0.014

<0.38
0.004
0.028
0.465
<0.002
4.834
0.006
<0.002
0.210
<0.005
<0.002
<0.014
<0.008
0.084
6,7
Harriman
5/80-5/81
0000-0000
24
256
20.80



8.10
36.1



0.038
0.150

0.021


0.120


0.017


BQL

0.180

2.500

0.002
0.120



BQL

17 6,7
Harriman Kingston
9/85-8/86 5/80-6/81
0000-0000
24 24
330 169
21.00 24.60



8.70
36.1



0.044
0.120

BQL


0.097


0.010


BQL

0.194

2.400

0.002
0.200



BQL

6,7
Portage
3/79-5/81
0000-0000
24
271
11.00



6.81
10.5



0.011
0.045

0.027


0.049


0.003


BQL

0.061

1.400

0.001
0.075



BQL

6,7
Topeka
8/79-5/81
0000-0000
24
286
12.50



6.05
11.6



0.045
0.250

0.031


0.090


0.004


BQL

0.163

1.100

0.000
0.190

i

BQL

8(a)
El Paso
1980
24
10
27.16





0.155
0.025

0.070
0.332


0.001
0.036
0.134
0.127

0.004


0.001

0.481

0.823

0.002
0.436


0.003

0.055
8(a)
Inglenook
1980
24
8
32.03





0.082
0.001

0.040
0.326

0.003
0.002
0.032
0.281
0.408

0.037


0.001
0.008
0.309

2.655

0.001
0.685




0.133
8(a)
Braldwood
1980
24
1
28.20





0.089


0.003
0.084



0.024
0.071
0.052

0.001


0.001

0.041

2.060

0.001
0.220




0.011
8(a)
Kansas City KS
1980
24
8
25.66





0.091
0.003

0.027
0.519


0.004
0.032
0.189
0.311

0.006


0.002
0.013
0.180

1.816

0.001
0.434


0.004

0.034
  References are listed in Table 1 Appendix

* Values for this size fraction are calculated
 Associated notes are explained in Table 1.

from the average measured values reported for the other two size fractions.
                                                                                                                                        w
-------
              PM2.5 COMPOSITION (24-h AVG)
                        CENTRAL U.S.
Units « ug/m3
o
H

O
C
O
H
o
h~<
H
m
Ref
Site
Dates
Houre
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
*Ba
Br
Ca
Cd
8(a)
Minneapolis
1980
24
6
15.50






0.004

0.047
0.103

Cl |
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Nl
P
Pb
Rb
S
Sb
Se
SI
Sn
Sr
Tl
V
Zn
0.001
0.035
0.087
0.092

0.005


0.001

0.308

0.907

0.001
0.169




0.045
8(a)
Kansas City MO
1980
24
3
16.77






0.007

0.064
0.213


0.002
0.021
0.140
0.142

0.006


0.001

0.369

0.763


0.177




0.046
8(a)
Akron
1980
24
7
36.09





0.046
0.012

0.039
0.110


0.010
0.037
0.609
0.268

0.085


0.006
0.059
0.412

3.419

0.008
0.522


0.009

0.150
8(a)
Cincinnati
1980
24
2
29.80





0.062
0.013

0.024
0.062


0.003
0.024
0.174
0.136

0.011


0.004
0.043
0.343

2.876

0.005
0.328


0.003

0.053
8(a)
Buffalo
1980
24
14
38.75





0.192
0.009

0.003
0.218


0.002
0.026
0.671
0.310

0.033


0.008
0.060
0.359

3.706

0.005
0.241



0.001
0.078
8(a)
Dallas
1980
24
4
28.93





0.111
0.033

0.223
0.691


0.005
0.043
0.248
0.125

0.015


0.002
0.018
1.066

1.514


0.442


0.007
0.002
0.054
8(a)
St Louis
1980
24
5
23.06





0.119
0.003

0.025
0.090



0.018
0.076
0.126

0.002


0.002
0.020
0277

2.333

0.002
0.170

i


0.023
18(k)
St Louis
8-9/76
6-12
34.00





0.203
0.002
0.020
0.132
0.132
0.004
0.087
0.006
0.029
0.275
0.261

0.036


0.004
0.001
0.688
0.000
4.655
0.006
0.004
0.458
0.009
0.002
0.112
0.002
0.101
6,7 17
St Louis St Louis
9/79-6/81 9/85-8/86
0000-0000
24 24
306 311
19.00 17.70



8.10 8.00
10.3 9.7



0.078
0.101

0.052


0.190


0.021


0.003

0.327

2.100

0.002
0.160



BQL

6.7
Steubenville
4/79-4/81
0000-0000
24
499
29.60



12.80
25.2



0.042
0.097

0.092


0.590


0.029


0.005

0.216

4.700

0.005
0.290



0.011

                References are listed In Table 1 Appendix,

                Values for this size fraction are calculated
 Associated notes are explained In Table 1.

from the average measured values reported for the other two size fractions.
-------
               PM10 COMPOSITION (24-hr AVG)
                                            EASTERN U.S.
 •n
 H
 6
 o
 z
 o
 H
O
 d
 o
 H
 m
n
N-H

3
Units a ug/m3
Ref
Site
Dates
Hours
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Ni
P
Pb
Rb
S
Sb
Se
SI
Sn
Sr
Tl
V
Zn
1
-------
PM10 COMPOSITION  (24-hr AVG)
                                       WESTERN U.S.
Units * ug/m3
Ref
Site
Dates
Hours
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
C!
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Nl
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
Ti
V
Zn
8(a.q)
Res.Tr.Pk
1980
24
3
36.53





0.679
0.002

0.010
0.121


0.002
0.026
0.302
0.216

0.006


0.001
0.042
0.119

3.058

0.002
1.737


0.021

0.025
9(9)
Los Angeles
Summer'87
4,5 and 7
1 1 days
67.40
11.61
3.19
9.47
11.28

0.758
0.007
0.070
0.016
0.585

1.119
0.023
0.022
0.836
0.237
0.335
0.033

1,632
0.005
0.187
0.084

3.353

0.008
2.040

0.018
0.077
0.005
0.114
9(g)
Los Angeles
Fall'87
4 and 6
6 days
98. 7u
23.35
8.49
27.50
5.39

0.847
0.019
0.127
0.072
1.190

0.880
0.042
0.178
2.192
0.460
0.287
0.063

0.518
0.005
0.099
0.251

2.262

0.010
2.162

0.024
0.165
0.009
0.293
10fl)
San Joaquln Valley
6'8&-6'89
24
~35
74.05
10.59
5.62
10.55
3.62

3.570

0.051
0.015
1.057

0.487
0.010
0.087
1.633
0.820

0.037


0.010
0.059
0.061
0.004
1.463

0.001
8.037

0.014
0.147
0.014
0.094
110)* 5(d)
Phoenix Boise
10/13/89-1/17/90 12/86-3/87
7am-7pm-7a
6h.2x/day 12
~ 100 days
62.45
14.56
8.30
4.46
2.34

2.67
BQL
0.01
0.01
2.10
BQL
0.56
0.01
0.04
1.47
0.88
BQL
0.05
BQL
BQL
0.01
0.05
0.06
BQL
0.62
BQL
BQL
7.44
BQL
0.01
0.14 '
BQL
0.09
12(0 B(a,q)*
Nevada Tarrant CA
11/86-1/87 1980
00-2400
24 24
24 6
100.90





2.407


0.149
4.543


0.007
0.077
1.257
0.441

0.067


0.006
0.002
0.786

2.888


5.791


0.093

0.147
8(a,q)*
Five Points CA
1980
24
3
124.37





7.317


0.019
1.786

0.026
0.007
0.037
3.275
1.437

0.055


0.037
0.155
0.105

1.422

0.001
16.657


0.277
0.013
0.032
8(a,q)*
Riverside CA
1980
24
4
106.26





3.549


0.065
5.082

0.173
0.005
0.061
2.015
1.081

0.049


0.013
0.144
0.489

2.373

0.001
7.778


0.182
0.003
0.059
References are listed
  Values Tor this size
In Table 1 Appendix. Associated notes are explained In Table 1.
fraction are calculated from the average measured values reported for the other two size fractions.
-------
PM10 COMPOSITION  (24-hr AVG)
                                         CENTRAL U.S.
Units g ug/m3
Ref
Site
Dates
Hours
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Ni
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
Ti
V
Zn
8(a.q)*
San Jose CA
1980
24
6
66.68





2.053
0.001

0.250
0.771

0.480
0.009
0.071
1.214
0.508

0.027


0.014
0.045
1.119

1.109


5.506


0.086
0.002
0.105
8(a,q)*
Honolulu
1980
24
1
46.90





2.992


0.023
1.981

1.456
0.009
0.025
1.384
0.665

0.034


0.005
0.002
0.093

0.571


6.129


0.130
0.001
0.019
8(a,q)*
Winnemucca
1980
24
5
65.42





6.925


0.010
2.177

0.176
0.006
0.043
1.995
1 1.200

0.044


0.003

0.063

0.573


12.817


0.173

0.026
8(a,q)*
Portland
1980
24
4
117.55





6.932
0.014

0.121
1.459

0.197
0.019
0.109
2.059
0.805

0.108


0.036
0.028
0.537

2.371

0.001
12.505


0.191
0.018
0.119
8(a,q)*
Seattle
1980
24
1 .
36.00





2.296
0.008

0.033
0.585

0.228
0.005
0.041
1.001
0.231

0.022


0.007
0.006
0.292

0.952

0.001
4.424


0.091

0.093
8(a.q)* 13(q)*
Albuquerque Denver
12/84-3/85 1/11-30/82
7am-7pm-7am 6am-6pm-6am
12 12
~26
56.46
7.11
2.15
2.22
2.45

3.294
<0.004
0.089
0.127
0.705
0.018
1.287
<0.018
0.018
1.033
0.727

0.031


0.008
0.155
0.424
0.005
0.709
<0.004
<0.004
7.737
<0.004
; 0.009
0.09
<0.004
0.085
14(m) 14(aa) 15(3)*
Urban Denver Non-urban Denver Chicago
11/87-1/88 11/87-1/88 7/94
9am-4pm-9am 9am-4pm-9am 0800-0800
7417 7&17 24
~136 ~150 16
28.54
5.39
1.31

5.46

0.269
<0.0043
<0.130
0.011
0.761
<0.041
0.047
<0.0073
0.017
0.432
0.161
0.118
0.013
<0.0041
0.022
<0.0018
0.035
0.032

1.363
<0.059
<0.0017
0.813
<0.070

0.019
<0.013
0.090
References are listed
  Values for this size
in Table 1 Appendix. Associated notes are explained in Table 1.
fraction are calculated from the average measured values reported for the other two size fractions.
-------
D
O

2
O
H
O
c
O
H
m
o
?o

n
                     PM10 COMPOSITION (24-hr AVG)
CENTRAL U.S.
Units » ug/m3
Ref
Site
Dates
Hours
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Ni
P
Pb
Rb
S
Sb
Se
SI
Sn
Sr
TI
V
Zn
16(q)*
Houston
9/10-19/80
12
20
63.40
8.78
1.42
2.22
15.52

1.216
<0.015
0.139
0.091
2.935
<0.012
0.398
0.007
0.046
0.766
0.289

0.035

<1.49
0.008
0.128
0.589
<0.006
4.83
0.006
<0.003
3.200


0.036
<0.045
0.142
6,7(P.q) 17*
Harriman Harriman
5/80-5/81 9/85-8/86
0000-0000
24 24
256 330
32.50 30.00



11.14 8.70
36.1



0.052
1.800

0.050


0.690


0.038


0.001

0.237

2.500

0.002
2.000



ND

6J(p.q)
Kingston
5/80-6/81
0000-0000
24
169
35.40



13.63




0.056
0.960

0.018


0.360


0.027


ND

0.234

2.400

0.002
1.900



ND

6,7(p.q)
Portage
3/79-5/81
0000-0000
24
271
18.20



7.29




0.014
0.380

0.083


0.230


0.009


0.001

0.074

1.500

0.001
0.980



ND

6.7(P,q)
Topeka
8/79-5/81
0000-0000
24
286
26.40



6.60




0.055
2.400

0.031


0.580


0.020


0.001

0.203

1.200

0.000
2.500



ND

8(a,q)*
El Paso
1980
24
10
76.21





2.903
0.037

0.103
3.964

0.043
0.004
0.083
0.946
0.623

0.027


0.002

0.672

1.072

0.003
5.813


0.080

0.112
8(a,q)*
Inglenook
1980
24
8
72.45





2.508
0.001

0.061
2.924

0.003
0.006
0.059
1.474
0.717

0.07B


0.003
0.030
0.388

2.969

0.001
6.997


0.116

0.188
8(a,q)*
Braidwood
1980
24
1
56.90





2.020
0.002

0.006
1.490


0.002
0.044
0.727
0.355

0.018


0.002
0.014
0.054

2.632

0.002 '
5.987


0.083

0.023
8(a,q)*
Kansas City KS
1980
24
8
70.33





2.144
0.003

0.036
4.371


0.010
0.048
0.989
0.660

0.026


0.005
0.013
0.237

2.031

0.001
4.976


0.076

0.060
                    References are listed In Table 1 Appendix. Associated notes are explained In Table 1.

                      Values tor this size fraction are calculated from the average measured values reported for the other two size fractions.
                                                                                                                                         w
                                                                                                                                         I
-------
             PM10 COMPOSITION (24-hr AVG)
                                           CENTRAL U.S.
Units m ug/m3
Ref
Site
Dates
Hours
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Ni
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
Tl
V
Zn
8(a,q)«
Minneapolis
1980
24
6
46.35





2.191
0.005

0.069
1.674

0.293
0.003
0.057
0.831
0.402

0.031


0.002

0.406

1.131

0.001
4.848


0.062

0.072
B(a,q)«
Kansas City MO
1980
24
3
58.43





2.284
0.010

0.093
3.967

0.530
0.006
0.036
1.119
0.503

0.031


0.003

0.478

1.043


4.986


0.074

0.086
8(a,q)*
Akron
1980
24
7
70.90





2.555
0.015

0.064
1.541

0.572
0.024
0,055
2.249
0.592

0.129


0.011
0.059
0.509

3.870

0.008
5.531


0.116

0.219
8(a,q)*
Cincinnati
1980
24
2
62.95





2.972
0.013

0.041
1.374

0,103
0.005
0.038
1.057
0.499

0.032


0.007
0.080
0.442

3.265

0.005
6.961


0.099

0.201
8(a,q)*
Buffalo
1980
24
14
83.32





3,000
0.009

0.015
2.768

0.728
0.017
0.048
2.711
0.516

0.111


0.017
0.060
0.467

4.471

0.005
2.916


0.051
0.001
0.121
8(a,q)*
Dallas
1980
24
4
61.55





1.405
0.039

0.274
4.127

0.029
0.010
0.066
0.968
0.335

0.035


0.004
0.018
1.318

1.754


3.652


0.058
0.002
0.084
8(a,q)*
St. Louis
1980
24
5
56.82





3.956
0.004

0.046
1.874

0.053
0.001
0.032
0.663
0.417

0.019


0.004
0.020
0.372

2.612

0.002
4.638

i
0.058

0.044
18(x)*
St. Louis
8-9/76
6-12
62.00





1.412
0.003
0.054
0.179
2.949
0.005
0.344
0.015
0.043
1.493
0.653

0.071


0.009
0.099
0.877
0.002
5.188
0.007
0.005
4.928
0.010
0.009
0.587
0.006
0.175
6,7(p,q) 17*
SL Louis St Louis
9/79-6/81 9/85-8/86
0000-0000
24 24
306 311
31.40 27.60



11.14 8.00
9.7



0.099
1.600

0.145


0.770


0.040


0.005

0.415

2.300

0.002
2.100



ND

6,7(p,q)
Steubenville
4/794/81
0000-0000
24
499
46.50



17.60




0.052
1.120

0.303


2.200


0.068


0.008

0.259

5.500

0.005
2.300



0.013

o
o

z
o
H

o
c
o
H
m

o
?o

O
*—I
H
m
             References are listed

               Values for this size
in Table 1 Appendix. Associated notes are explained in Table 1.

fraction are calculated from the average measured values reported for the other two size fractions.
-------
O
O
Z
O
H
O
G
O
O
a
             COARSE COMPOSITION  (24-hr AVG)     EASTERN U.S.
                                                                          Units = ug/m3
Ref
Site
Dates
Hours
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
AS
A3
Ba
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Nl
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
Ti
V
Zn
1(0)
Smoky Mtns
9/20-26/78
12
12
5.60





<0.300
<0.001

0.005
0.322

<0.012

<0.005
0.118
0.108




<0.002

0.014

<0.560

<0.0006
0.580


0.018

<0.004
1(0)
Shenandoah
7/23-5/08/80
12
28
7.40



078

0.311
<0.002

0.003
0.304

0.179

0.006
0.158
0.129

<0.006


<0.003

0.009

<0.711

<0.001
0.813


0.017

0.006
2(b)
Camden
7/14-8/13 '82
6am-6pm-6am
12
50
11.40
<3.00
0.42
0.57
<0.90

0.550


0.015
0.360
<0.006
0.069
<0.009

0.490
0.151

0.011


0.004

0.054

0.230
0.181
<0.0015
1.610
<0.009
0.002
0.065
0.007
0.030
3(ab) 4(c) 5(d) 5(d)
Philadelphia Deep Creek Raleigh Roanoke
7/25-8/14/94 8/83 1/85-3/85 10/88-2/89
4x daily 7am-7pm-7a 7am-7pm-7am
24 6 12 12
21 98
8.42





0.325


0.003
0.421

0.047

0.014
0.352
0.100
0.104
0.006

0.136
0.002
0.027
0.013

BQL

BQL
0.933


0.030
BQL
0.052
6,7(o,p)*
Watertown
5/79-6/81
0000-0000
24
354
9.30



2.44




0.022
0.209

0.305


0.276


0,006




0.076

0.200


1.000





8(a.o)
Hartford
1980
24
2
27.85





1.875


0.046
0.864

0.302
0.008
0.026
1.070
0.310

0.021


0.005
0.033
0.171

0.428


4.517


0.094
0.008
0.054
8(a,o)
Boston
1980
24
1
105.60





3.458
0.001

0.025
1.069

0.301
0.004
0.023
1.612
0.533

0.029


0.022
0.016
0.177

0.502


6.760


0.154
0.008
0.054
References are listed In Table 1 Appendix.  Associated notes are explained In Table 1.

  Values for this size fraction are calculated from the average measured values reported for the other two size fractions.
-------
COARSE COMPOSITION  (24-hr AVG)
WESTERN U.S.
Units « ug/m3
Ref
Site
Dates
Hours
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Ni
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
Tl
V
Zn
8(a,o)
Res.Tr.PK
1980
24
3
8.17


a


0.606


0.003
0.086


0.002
0.010
0.182
0.068

0.003




0.013

0.223


1.387


0.021

0.007
9(9)*
Los Angeles
Summer'87
4,5 and 7
11 days
26.30
3.34
0.82
5.13
1.87

0.723
SQL
0.055
0.003
0.563

1.026
0.002
BQL
0.737
0.196
0.311
0.017

1.431
BQL
0.127
0.046

0.520

BQL
1.988

BQL
0.072
BQL
0.024
9(9)*
Los Angeles
Fall'87
4 and 6
6 days
8.50
4.89
1.21
4.86
1.01

0.597
0.004
0.084
0.006
0.854

0.426
0.017
BQL
1.635
0.243
0.212
0.021

0.052
BQL
0.053
0.066

0.264

BQL
1.642

BQL
0.106
0.003
BQL
10«*
San Joaquin Valley
6'88-6'89
24
~35
44.17
5.71
2.38
2.38
0.62

3.418
0.000
0.040
0.006
0.961

0.393
0.007
BQL
1.453
0.632
0.000
0.031

0.000
BQL
0.052
0.032

0.222

0.000
7.577

0.012
0.130
BQL
0.016
11(j) 5(d)
Phoenix Boise
10/13/89-1/17/90 12/86-3/87
7am-7pm-7a
6h. 2x/day 12
~ 100 days
33.09
4.46
0.84
0.86
0.37

2.539
<0.002
<0.077
0.002
1.929
<0.016
0.194
0.008
0.021
1.259
0.669

0.032
<0.005

0.003
0.038
0.022
0.003
0.178
<0.030
< 0.002
7.013
<0.026
0.014 ,
0.121
<0.014
0.034
12(f) 8(a,o)
Nevada Tarrant CA
11/86-1/87 1980
00-2400
24 24
24 6
43.85





2.230


0.047
4.088


0.005
0.030
0.941
0.255

0.035


0.003
0.002
0.167

0.310


5.208


0.083

0.052
8(a,o)
Five Points CA
1980
24
3
92.57





7.078


0.004
1.636

0.022
0.006
0.013
3.059
1.193

0.050


0.012
0.148
0.018

0.293


16.001


0.272
0.007
0.016
8(a,o)
Riverside CA
1980
24
4
71.03





3.513


0.028
4.781

0.164
0.005
0.021
1.888
0.961

0.042


0.006
0.144
0.113

0.720


7.544


0.182

0.030
References are listed In Table 1 Appendix. Associated notes are explained In Table 1.
* Values for this size fraction are calculated from the average measured values reported for the other two size fractions.
-------
             COARSE COMPOSITION  (24-hr AVG)
                                                           CENTRAL U.S.
                                                                                Unto = ug/m3
Ref
Site
Dates
Hours
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Ni
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
Ti
V
Zn
8(a,o)
San Jose CA
1980
24
6
30.40





1.930


0.062
0.682

0.430
0.006
0.028
1.066
0.260

0.021


0.008
0.032
0.228

0.257


5.214


0.086

0.044
8(a.o)
Honolulu
1980
24
1
25.60





1.865


0.006
0.957

0.938
0.005
0.007
0.6581
0.294

0.014


0.003

0.022

0.258


3.766


0.067

0.008
8(a,o)
Wlnnemucca
1980
24
5
55.74





6.564


0.004
1.934

0.176
0.006
0.017
1.764
1.051

0.041


0.002

0.021

0.215


11.903


0.164

0.015
8(a.o)
Portland
1980
24
4
80.36





6.351
0.002

0.028
1.305

0.176
0.010
0.037
1.789
0.587

0.056


0.009
0.011
0.115

0.427


12.128


0.186
0.004
0.038
8(a,o)
Seattle
1980
24
1
25.30





2.294
0.002

0.014
0.548

0.228
0.003
0.017
0.903
0.151

0.018


0.001

0.077

0.121


4.332


0.091

0.034
5(d) 13(o)
Albuquerque Denver
12/84-3/85 1/11-30/82
7am-7pm-7am 6am-6pm-6a
12 12
~26
35.73



0.39

2.900

0.058
0.024
0.658
0.012
1.235
<0.009
0.008
0.954
0.648

0.021


0.005
0.113
0.099
0.005
<0.48


7.460

0.009
0.090

0.039
14(m) 14(ab) 15(s)
Urban Denver Non-urban Denver Chicago
1 1 /87-1 /88 11 /87-1 /88 7/94
9am-4pm-9am 9am-4pm-9am 0800-0800
7&17 78.17 24
~136 ~150 16
14.97





0.223
<0.0013
<0.038
0.007
0.716
<0.012
0.036
<0.0024
0.006
0.344
0.101
0.106
0.008
<0.0017
<0.017
<0.0007
0.027
0.005

0.043
<0.017
<0.0006
0.739
<0.021

0.019
<0.004
0.038
c
o

"Z
o
H

O
c
o
H
m
n

H
m
References are listed

  Values for this size
in Table 1 Appendix  Associated notes are explained in Table 1.

fraction are calculated from the average measured values reported for the other two size fractions.
-------
                 COARSE COMPOSITION  (24-hr AVG)
                                                        CENTRAL U.S.
O
o
z
o
H
O
H
n
h— H
H
m
                                                                  Units g ug/m3
Ref
Site
Dates
Hours
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
Cl
Cr
Cu
Fe
K
Mg
Mn
Mo
Na
Nl
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
Ti
V
Zn
16(o)
Houston
9/10-19/80
12
20
24.80
3.10

1.63
0.91

1.093
<0.006
0.091
0.036
2.780
<0.006
0.366
0.007
0.018
0.604
0.170

0.021

<0.74
0.004
<0.1
0.124
<0.003
<1.29
<0.009

2.990
<0.009
<0.008
0.036
<0.03
0.058
6,7(o.p)*
Harrlman
5/80-5/81
0000-0000
24
256
11.70



3.04




0.014
1.650

0.029


0.570
1

0.021


0.001

0.057

BQL


1.880





17 6,7(o,p)*
Harriman Kingston
9/85-8/86 5/80-6/81
0000-0000
24 24
330 169
9.00 10.80








0.012
0.840

0.018


0.263


0.018


BQL

0.040

BQL


1.700





6,7(o,p)*
Portage
3/79-5/81
0000-0000
24
271
7.20



0.48




0.003
0.335

0.056


0.181


0.006


0.001

0.013

BQL


0.905





6,7(o,p)*
Topeka
8/79-5/81
0000-0000
24
286
13.90



0.55




0.010
2.150

0.000


0.490


0.016


0.001

0.040

BQL


2.310





8(a,o)
El Paso
1980
24
10
49.05





2.748
0.012

0.033
3.632

0.043
0.003
0.047
0.812
0.496

0.023


0.001

0.191

0.249

0.001
5.377

i
0.077

0.057
8(a,o)
Inglenook
1980
24
8
40.43





2.426


0.021
2.598


0.004
0.027
1.193
0.309

0.041


0.002
0.022
0.079

0.314


6.312


0.116

0.055
8(a,o)
Braldwood
1980
24
1
28.70





1.931
0.002

0.003
1.406


0.002
0.020
0.656
0.303

0.017


0.001
0.014
0.013

0.572

0.001
5.767 '


0.083

0.012
8(a,o)
Kansas City KS
1980
24
8
41.67





2.284
0.003

0.029
3.754

0.530
0.004
0.015
0.979
0.361

0.025


0.002

0.109

0.280


4.809


0.074

0.040
                                                                                                                                     w
                                                                                                                                     I
References are listed

* Values for this size
In Table 1 Appendix. Associated notes are explained In Table 1.

fraction are calculated from the average measured values reported for the other two size fractions.
-------
 O
 O
 z
 O

O
 C
 O
 H
m

o
?a
o

m
              COARSE COMPOSITION (24-hr AVG)
                                   CENTRAL U.S.
Units =; ug/m3
Ret
Site
Dates
Houra
Dur
Number
Mass
OC
EC
Nitrate
Sulfate
Acidity
Al
As
Ba
Br
Ca
Cd
C!
Cr
Cu
8(a,o)
Minneapolis
1980
24
6
3o.es





2.191
0.001

0.022
1.571

0.293
0.002
0.022
Fe 0.744
K
Mg
Mn
Mo
Na
Nl
P
Pb
Rb
S
Sb
Se
Si
Sn
Sr
Tl
V
Zn
0.310

0.026


0.001

0.098

0.224


4.679


0.062

0.027
8(a,o)
Kansas City MO
1980
24
3
4l.6>





2.284
0.003

0.029
3.754

0.530
0.004
0.015
0.979
0.361

0.025


0.002

0.109

0.280


4.809


0.074

0.040
8(a,o)
Akron
1980
i
24
7
34.81





2.509
0.003

0.025
1.431

0.572
0.014
0.018
1.640
0.324

0.044


0.005

0.097

0.451


5.009


0.107

0.069
8(a.o)
Cincinnati
1980
24
2
33.15





2.910


0.017
1.312

0.103
0.002
0.014
0.883
0.363

0.021


0.003
0.037
0.099

0.389


6.633


0.096

0.148
8(a,o)
Buffalo
1980
24
14
44.57





2.808


0.012
2.550

0.728
0.015
0.022
2.040
0.206

0.078


0.009

0.108

0.765


2.675


0.051

0.043
8(a,o)
Dallas
1980
24
4
32.63





1.294
0.006

0.051
3.436

0.029
0.005
0.023
0.720
0.210

0.020


0.002

0.252

0.240


3.210


0.051

0.030
8(a,o)
St. Louis
1980
24
5
33.76





3.837
0.001

0.021
1.784

0.053
0.001
0.014
0.587
0.291

0.017


0.002

0.095

0.279


4.468


0.058

0.021
18(k.r)
St. Louis
8-9/76
6-12
28.06





1.209
0.001
0.034
0.047
2.817
0,001
0.257
0.009
0.014
1.218
0.392

0.035


0.005
0.098
0.189
0.002
0.533
0.001
0.001
4.470
0.001
0.007
0.475
0.004
0.074
6.7(o,p)* 17
St Louis St Louis
9/79-6/81 9/85-8/86
0000-0000
24 24
306 311
12.46 9.§6



3.04




0.021
1.499

0.093


0.580


0.019


0.002

0.088

0.200


1.940



BQL

6.7
-------
                                             B-16
List of References

1.     Stevens, R.K., Dzubay, T.G., Lewis, C.W., and Shaw, R.W. (1984). Source apportionment
       methods applied to the determination of the origin of ambient aerosols that affect visibility in
       forested areas. Atmos. Environ. IS 261.

2.     Dzubay, T.G. and Stevens, R.K. (1988). A composite receptor model applied to Philadelphia
       aerosol. Environ. Sci. Techn. 22 46-

3.     Unpublished data from J. Pinto, U.S. EPA, Research Triangle Park, NC (1995>.

4.     Vossler,  T.L., Lewis,  C.W.,  Stevens,  R.K.,  Dzubay,  T.G.,  Gordon,  G.E.,  Tuncel,
       S.G.,Russworm, G.M., and Keeler, G.J.  (1989).  Composition and origin of summertime air
       pollutants at Deep Creek Lake, Maryland. Atmos. Environ. 211535.

5.     Stevens, R.K., Hoffman, A.J., Baugh, J.D., Lewis, C.W., Zweidinger,  R.B., Cupitt, L.T.,
       Kellogg, R.B. and Simonson, J.H. (1995).  A comparison of air quality measurements in
       Roanoke, Va, and other integrated air cancer project monitoring locations.  In: Measurement of
       Toxic and Related Air Pollutants. Proceedings of the 1993 U.S. EPA/A&WMA International
       Symposium. A&WMA, Pittsburgh,  PA, p!85.

6.     Spengler, J.D. and Thurston, G.D.  (1983). Mass and elemental composition of fine and coarse
       particles in six US cities. JAPCA 221162.

7.     Dockery, D.W., Pope, C.A., Xu, X., Spengler, J.D., Ware, J.H., Fay, M.E., Ferris, E.G. and
       Speizer, F.E.  (1993). An association between air pollution and mortality in  six U.S. cities. New
       Eng. J. Medicine 222 1753.

8.     Davis, B.L. Johnson, L.R., Stevens, R.K., Courtney, WJ. and Safriet, D.W. (1984). The quartz
       content and elemental composition of aerosols from selected sites of the EPA inhalable paniculate
       network. Atmos. Environ. 18 771.

9.     Chow, J.C., Watson, J.G., Fujita, E.M., Lu, Z.,  Lawson, D.R. and Ashbaugh, L.L. (1994).
       Temporal and spatial variations of PM2.S and PM10 aerosol in the Southern California Air
       Quality Study. Aerosol Sci. and Tech. 212061.

10.    Chow, J.C., Watson, J.G., Lowenthal, D.H., Solomon, P.A., Magliano, K.L. Ziman, S.D. and
       Richards, L.W. (1993). PM10 and PM2.5 compositions in California's San Joaquin Valley.
       Aerosol Sci & Tech. 1£ 105.

11.    Unpublished data from the Desert Research Institute (1995).

12.    Chow, J.C., Watson, J.G., Pritchett, L., Lowenthal, D.H., Frazier, C., Neuroth, G. and Evans
       K. (1990). Wintertime visibility in Phoenix, Arizona. Paper 90-66.6 in Proceedings of the 83rd
       National Meeting of the Air & Waste Management Association, Pittsburgh, PA, 24-29 June,
       1990.

13.    Lewis, C.W., Baumgardner,  R.E., Stevens, R.K.,  and Russworm,  G.M. (1986). Receptor
       modeling study of Denver winter haze. Environ. Sci. Techn. 2Q 1126.
                                                        DRAFT-DO NOT QUOTE OR CITE
-------
                                          B-17

14.     Watson, J.G., Chow, J.C., Richards, L.W., Neff, W.D., Andersen, S.R., Dietrich, D.L. Houck,
       I.E.  and Olmez, I. (1988). The 1987-88 metro  Denver brown cloud study, vol 3: data
       interpretation. Desert Research Institute. Document No. 8810 1F3.

15.     Unpublished data (1995).

16.     Johnson, D.L., Davis, B.L., Dzubay,  T.G.,  Hasan, H., Crutcher, E.R.,  Courtney,  W.J.,
       Jaklevic, J.M., Thompson, A.C., and Hopke, P.K.  (1984). Chemical and physical analyses of
       Houston aerosol for interlaboratory comparison of  source apportionment procedures. Atmos.
       Environ. 1£, 1539.

17.     Dockery, D.W., Schwartz, J. and Spengler, J.D. (1992). Air pollution and daily mortality:
       associations with particulates and acid aerosols. Environ. Research 52 362.

18.     Dzubay, T.G. (1980). Chemical elements balance method applied to dichotomous sampler data.
       In: Annals of the New York Academy of Sciences 338 126.

19.     Stevens, R.K. (1985). Sampling and analysis methods for use in source apportionment studies
       to determine impact of wood burning on fine particle mass. Environment International H 271.

20.     Mukerjee, S., Stevens, R.K., Vescio, N., Lumpkin, T.A., Fox, D.L., Shy, C. and Kellogg, R.B.
       (1993). A methodology to apportion ambient air measurements to investigate potential effects on
       air quality near waste incinerators. In: Proceedings of  the  1993 Incineration Conference,
       Knoxville, TN. 527.

21.     Koutrakis,  P.  and  Spengler, J.D.  (1987).  Source apportionment of  ambient particles in
       SteubenvDle, OH using specific rotation factor analysis. Atmos. Environ. 2JL 1511.

22.     Chow, J.C.,   Watson, J.G., Ono,  D.M.  and Mathai,  C.V. (1993). PM10 standards and
       nontraditional paniculate source controls: a summary of the A&WMA/EPA international specialty
       conference. Air & Waste 43 74.

23.     Solomon, P.A.  and Moyers, J.L. (1986). A chemical characterization  of wintertime haze in
       Phoenix, Arizona. Atmos. Environ.  2_Q 207.

24.     Ellenson, W.D., Schwab,  M., Egler, K.A.,  Shadwick,  D. and  Willis, R.D.  (1994).  Draft
       technical report for the pilot project of Lower Rio Grande Valley environmental study. ManTech
       Environmental Technology, Inc. Submitted to the U.S. EPA.

25.     Chow, J.C., Watson, J.G., Frazier, C.A., Egami, R.T., Goodrich, A. and Ralph, C. (1988).
       Spatial and temporal source contributions to PM10 and PM2.5 in Reno,  NV. In:  Transactions:
       PM10 Implementation of Standards, an APCA/EPA international  specialty conference.  Air
       Pollution Control Association, 439.

26.     Pope, C.A., Schwartz, J. and Ransom, M.R. (1992). Daily mortality and PM10 Pollution in Utah
       Valley.  Archives of Environ. Health 47 211.

27.     Fairley, D. (1990). The relationship of daily mortality to suspended particulates in Santa Clara
       county 1980-1986. Environ. Health Perspectives £9j  159.
                                                      DRAFT-DO NOT QUOTE OR CITE
-------
                                           B-18

28.    Chow, J.C., Watson, J.G., Lowenthal, D.H., Solomon, P.A., Magliano, K.L. Ziman, S.D. and
       Richards, L.W. (1992). PM10 source apportionment in California's San Joaqin Valley. Atmos.
       Environ. 26A 3335.

29.    Chow, J.C., Fairley, D., Watson, J.G., De Mandel, RM Fujita, E., Lowenthal, D.H.,  Lu, Z.,
       Frazier, C.A., Long, G. and Cordova, J. (1994). Source apportionment of wintertime PM10 at
       San Jose, CA. J. Environ Engineers, in press.

30.    Watson, J.G., Chow, J.C., Lu, Z.,  Fujita, E.M.,  Lowenthal, D.H.,  Lawson,  D.R. and
       Ashbaugh, L.L. (1994).  Chemical mass  balance source apportionment of PM10 during the
       Southern California Air Quality Study. Atmos. Environ. 12 2061.

31.    Wolff, G.T., Ruthkosky,  M.S., Stroup, D. adn Korsog, P.E. (1991). A characterization of the
       principal PM10 species in Claremont (summer) and Long Beach (fall) during SCAQS. Atmos.
       Environ. 25A 2173.

32.    Ashbaugh, L.L., Watson, J.G. and Chow, J. (1989).  Estimating fluxes from California's dry
       deposition monitoring data. Paper 89-65.3 in: Proceedings of the 82nd Annual Meeting of the
       Air & Waste Management Association,  Anaheim, CA.

33.    Chow, J.C.,  Watson, J.G.,  Solomon, P.A., Thuillier,  R.H.,  Magliano, K.L. Ziman, S.D.,
       Blumenthal, D.L. and Richards, L.W. (1994). Planning for SJVAQS/AUSPEX Paniculate matter
       and visibility sampling and analysis. In: Planning and  Managing Regional Air Quality, ed. by
       Paul Solomon. CRC Press, Inc.

34.    Schwartz, J.  (1994).  Air pollution and hospital admissions for the elderly in Birmingham,
       Alabama. Am. J. Epidemiology. 139 589.

35.    Schwartz, J. and Dockery, D.W. (1992). Increased mortality in Philadelphia associated with daily
       air pollution concentrations. Am.  Rev. Respir. Dis. 145 600.

36.    Suh, H.H., Koutrakis, P. and Spengler, J.D. (1993). Validation of personal exposure models for
       sulfate and aerosol strong acidity. J. Air Waste Manage.  Assoc.  4J 845.

37.    Conner, T.L., Miller, J.M., Willis, R.D,, Kellogg, R.B. and Dann, T.F. (1993). Source
       apportionment of fine and coarse particles in Southern Ontario, Canada. In: Proceedings of the
       86th Annual Meeting of the Air & Waste Management Association, Denver, CO. Paper 93-TP-
       58.05.

38.    Kim, B.M., Zeldin, M. and Liu, C. (1992). Source apportionment study for state implementation
       plan development in  the Coachella  Valley. In: PM10  Standards and nontraditional paniculate
       source controls.  Chow and Ono,  Eds., Air & Waste Management Association, Pittsburgh, PA,
       979.

39.    Houck, J.E., Rau] J.A., Body, S. and  Chow, J.C. (1992).  Source apportionment - Pocatello,
       Idaho PM10 nonattainment area. Ibid, 219.
                                 /
40.    Chow, J.C., Watson, J.G., Lowenthal, D.H., Frazier, C.A., Hinsvark, B.A., Pritchett, L.C. and
       Neuroth,  G.R. (1992).  Wintertime PM10  and PM2.5 chemical compositions and source
       contributions in Tuscon, Arizona. Ibid,  231.
                                                      DRAFT-DO NOT QUOTE OR CITE
-------
                                               B-19
41.    Vermette, S.J., Williams, A.L. and Landsberger, S. (1992). PM10 source apportionment using
       local surface dust profiles: examples from Chicago. Ibid, 262.

42.    Thanukos, L.C., Miller, T., Mathai, C.V., Reinholt, D. and Bennett, J. (1992). Intercomparison
       of PM10 samplers and source apportionment of ambient PM10 concentrations in Rillito, Arizona.
       Ibid, 244.

43.    Skidmore, L.W., Chow,  J.C. and Tucker, T.T. (1992). PM10 air quality assessment for the
       Jefferson County, Ohio air quality control region. Ibid, 1016.
                                                          DRAFT-DO NOT QUOTE OR CITE
-------
            APPENDIX C
Summary of PM2 5 Air Quality Databases
    and Model for Predicting PM2 5
-------
External Review Draft                        C-l                         Do Not Quote or Cite
November 1995

Appendix C.  PM2 5 Databases and Models for Predicting PM2 5 from PM10 Values


PM2.5 Databases


       Most of the air quality analyses used all available PMjQ and PN^ 5 data (1982-1993)


from sites with both PM measurements in the AIRS, IMPROVE, NEPART and Inhalable


Particle Network (IPN) monitoring networks, and some analyses used data from the California


Air Resources Board (CARB) Dichot and Southern California Air Basin (SCAB) Intensive


Monitoring Network databases.  Table C-l describes the concurrent PMjQ and PM2 5


databases.  See SAI February 1995 report for more details.


       For the peak-to-mean analyses, the combined data from the AIRS, IMPROVE, IPN,


CARB Dichot and SCAB Intensive Monitoring Network databases were used.  NEPART data


were not used because of frequent cases with PM2 ^/PMjQ ratios above 1 (due to the use of


different measuring instruments).




Predicting Daily PM2 c Values


       Because there are more PMjQ data than fine particle data, some efforts were made to


predict PM2 c concentrations from PMjQ values.  However, variation monitoring techniques


and variation in the coarse fraction can complicate the ability to predict daily values,


especially in areas with relatively large coarse fractions. Predictions of annual PM2 5 values


are more reliable than estimates of daily PM2 5 values.


       In view of the difficulties hi predicting daily PM2 5 values from PMjQ mass alone,


alternative approaches to the ratio estimators were used to provide better estimates of PM2 5


based on PMin and other available data such as region, season, and windspeed.
-------
IMPROVE'
NFS
Class f areas
56
since 10/89
rural
data in-house

                                                                                                                         I
NESCAUM
(NEPART),
NESCAUM
Class I areas
         since 9/88
               NE, rural
             only PM2 5 is described in
             reference
AIRS
               Mostly Northeastern
               Urban sites
                    68,
                    (8 rural)
         since '83
               mostly NE,
               urban
IPN
EPA
All regions, but
most in northeast
36,
(6 rural)
1/82- 1/84
mostly NE,
urban
dlchots
CARS Dichot
Network
CARB
California sites
         routine since
         1/80
               W, mostly
               urban?
                                                                                          o
                                                                                          NJ
SJVAQS
DRI
San Joaquin Valley,
CA
6
6/88 - 6/89
SW,urban
& rural
3 urban, 3 rural
seasonal data summary in-
house
SNAPS-II
DRI
Reno, NV
         2/87 - 3/87
               SW, urban
             data (graph) In-house (JAPCA
             1990)
Phoenix PM10
DRI
Phoenix,, AZ
8
9/89-1/90
SW, urban
data summary In-house
Phoenix Urban
Haze
DRI
Phoenix,'A2
         9/89- 1/90
               SW, urban
             6-hr samples
             (mornlng/afteroon); data
             summary in-house
Tucson PMt0
DRI
Tucson, AZ
         9/89-1/90
               SW, urban
             data summary In-house
Tucson Urban
Haze
fJRI
Tucson, AZ
         9/89 • 1/90
               SW, urban
             6-hr samples
             (morning/afternoon)
                                                                                                                          to
                                  n
                                  «T
SCAB Intensive
Monitoring
SCAQMD
Downtown Los
Angeles, CA
          1/88- 12/86
               SW, urban
             data In-house
-------
	
fcftjOY " ""
#h>'M < ' -
Neighborhood-
Scale Rubidoux
Oregon AQSN
Jefferson
County SIP
PREVENT
Shenandoah
Visibility
MOHAVE
AUSPEX
CADMP
Acid Aerosol
Forest Response
Puget Sound Air
Toxics
ma*?* '
W*" 
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External Review Draft                          C-4                          Do Not Quote or Cite

November 1995




By significantly augmenting the database of PM9  5 concentrations, these regression




predictions could be used to provide more complete information on the impact of proposed




alternative PM9 c NAAQS formulations. The applicability of these results would depend
              4*t »?



upon the strength of the regression model (predictive accuracy).




       For the regression modeling the 1988-1993 AIRS PM database was combined with




wind speed data (daily maximum and daily mean) for the nearest monitor, and AIRS daily




maximum hourly ozone data (for the nearest monitor within 20 miles).




       The models  included regressions on selected measured factors and variables such as




season, region, wind speed, and daily maximum hourly ozone; however, the predictions of




daily PM7 r values still has uncertainties as represented by a low R squared correlation
         jLi • _J



statistic (R  = 0.4)  and by high mean squared errors of the predicted  ratio (0.025) and PN^ 5




concentration.










       The best model was selected using a stepwise regression procedure to avoid including




terms that would increase the complexity of the model without significantly improving the




model  accuracy.  This model expresses the  mean ratio as the sum of terms for season, land




use, region, log daily maximum hourly ozone concentration, log daily maximum wind speed,




log daily mean wind speed,  some of their two-factor interactions and  quadratic terms,




together with a multiple of PMjQ. (An interaction measures the extent to which the effect of




one variable varies  with the level of another variable.  For example, the inclusion  of a




season/region interaction term means that the model assumes that the  mean ratio for a season




is different for different regions.)
-------
External Review Draft
November 1995
                                      C-5
                                                       Do Not Quote or Cite
       The final model had a R-squared statistic of 0.4. The "typical" error, as defined by the

root mean square error divided by the mean measured value, is about 30 percent for the ratio

and about 40 percent for the predicted PN^ 5.  Table C-2 gives more information about the

regression models, including a list of the independent variables. For more details about this

table and about the regressions, see SAI, 1995.
  TABLE C-2. Summary of GLM ratio predictions for 1988-1993 using 3 regression
  models.
Model
                    Effects
                          1
Range of
Predicted
 Ratios
                                                              Mean Square Error
                                                              Predicted  Predicted
                                                 R-Square    Ratio
                                                            PM
                                                                            2 5
1.  Full
2.  Best
3.  PM
   Only
S,R,L,0,P,W,M,SR,
SL,SO,SW,SM,RL,RO,
RW,RM,LO,LW,LM,
OO,OW,OM,WW,WM,
MM
S,R,L,O,W,M,SR,SL,
SO,RL,RO,RW,RM,
LO,MM,OO,P
S,R,L,SR,LR,SL
                                   0.125 to
                                     1.005
                                                     0.402      0.0254     63.20
                                   0.164 to
                                    0.997

                                   0.241 to
                                    0.785
                                                     0.399      0.0254     63.01
                                                     0.345      0.0259     69.43
  1 S = Season; R = Region; L = Land use; P = PMjQ-, O = Log Ozone; W = Log
  Maximum Wind Speed; M = Log Mean Wind Speed.

  All predictions are based on 4,158 observations, of which 2,221  had
  PM1Q > 30 /xg/m3.
-------
External Review Draft
November 1995
C-6
Do Not Quote or Cite
                              Table C-3.  Regression Coefficients
Description
Intercept
11
ri
r2
r3
r4
61
62
83
M
W
O
MM
00
P
rl*sl
r2*Bl
r3*El
r4*6l
rl«s2
r2*s2
r3*B2
r4*B2
rl*s3
r2*e3
r3*63
rl*0
r2*O
r3*0
r4*O
rl*M
r2*M
r3*M
r4*M
ll*O
61*0
62*0
B3*O
Il*r3
rl*W
r2*W
r3*w
r4*W
11*61
11*62
11*63
Coefficient
1.3959325348
0.3073145307
-0.3776503620
-0.1340208501
-0.1666333810
-0.0279404757
-0.1074828313
0.0008228475
0.0378687052
0.0077850304
-0.0571402112
-0.3013312495
-0.0166049496
0.0272285221
-0.0005619142
-0.0063374696
-0.0234241617
-0.0022432622
-0.0039536140
-0.0034235951
0.0106803520
0.0030315657
0.0013630935
-0.0316804924
0.0050697115
-0.0041470165
0.0448202236
-0.0014492506
0.0457880844
0.0063878655
-0.0162975221
-0.0566163387
0.0015303057
-0.0048482228
-0.0839335316
0.0328830035
0.0006064914
0.0025819148
0.0243145834
0.0962484064
0.0682528572
-0.0026358922
-0.0120560988
0.0304714189
-0.0087578574
0.0130235897
Std. Error
0.1474182834
0.0956879182
0.1309241123
0.0539672399
0.0402760651
0.0229316883
0.0378706642
0.0228386788
0.0229151628
0.0246859620
0.0247969456
0.0597227364
0.0076897974
0.0074196893
0.0001437664
0.0108643150
0.0060784225
0.0036520019
0.0025380381
0.0072239755
0.0037837339
0.0024723039
0.0016068555
0.0134740214
0.0051831044
0.0033092445
0.0247292661
0.0105907134
0.0075674780
0.0043171802
0.0401053217
0.0187467621
0.0125849727
0.0096187141
0.0230356244
0.0086496791
0.0052878957
0.0054471383
0.0082318869
0.0428591060
0.0222493632
0.0157960596
0.0108329495
0.0147528462
0.0089204190
0.0082105759
                          P  = PMjO' O = log (daily maximum hourly ozone),
                          W  = log (daily maximum wind speed),
                          M  = log (daily mean wind speed) rl-r4, sl-s3,
                          11 are coded region, season, and land-use variable
-------
             APPENDIX D

       Strengths and Limitations
of Experimental Human and Animal Studies
-------
External Review Draft                                                   j)o Not Quote or Cite
November 1995                             D-l
                                     Appendix D
    STRENGTHS AND LIMITATIONS OF CONTROLLED HUMAN AND ANIMAL
                                      STUDIES

      As discussed above, the adverse effects of particulate matter exposure have been
shown to be consistent between historical and more recent studies. The effects can be severe
and tend to be concentrated in sensitive sub-populations who have pre-existing conditions or
characteristics that tend to make them vulnerable to respiratory insult (the very young and
old, asthmatics, COPD patients, patients with pneumonia etc). The additional risk of
reported mortality and morbidity from particulate matter exposure is relatively small in terms
of the whole population.  Therefore, large numbers of people must be exposed before effects
can be discerned in studies.  The question arises as to how to elucidate the mechanism of
action of particulate matter in humans. What are the considerations that must be taken into
account when an analysis of the body of human clinical data and experimental animal work is
done in  order to infer a plausible mechanism for particulate matter effects?
1.    Numbers of Individuals Affected
      An issue of primary concern is that of statistical power. The nature of the effect
described in epidemiological work is consistent, and serious, but occurring in a relatively
small fraction of the total population (1 in a  million increased risk for daily mortality).
Therefore, theoretically a relatively large number of animals would be needed to mimic the
frequency of response at similar doses. The use of a similar number of animals to mimic the
frequency of response to ambient air concentrations of particles which have been associated
with effect in humans is impractical.  Therefore, in many experimental paradigms,  relatively
large concentrations are often given investigate the response from a limited number of
animals. However, the questionable relevancy and sensitivity of such paradigms limits their
use in the determination of the mechanism of action of relatively  low changes in
concentrations of inhaled particulate matter.
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External Review Draft                                                     Do Not Quote or Cite
November 1995                              D-2
2.     Heterogeneity of Human Population
       The human population for which the effects are most demonstrable are a sub-
population from a genetically heterogenous group.  Furthermore, consistency of response is
highly variable among the population at risk (e.g., a relatively small group of asthmatics
have aggravation of symptoms and not all patients with pneumonia or COPD die as a result
of an increase in inhaled particle concentration). The CD suggests that for clinical studies
involving  asthmatics, differences among subjects may explain in part the differing results
between laboratories who study effects of acid aerosols.  As an example of differential
susceptibility to a respiratory insult, a minority of individuals (3-5%) who are exposed to
etiologic agents responsible for hypersensitivity pneumonitis (allergic alveolitis) will develop
disease.  Determinants of susceptibility for that disease have been described as both the
genetic  constitution of the individual and the presence of preexisting lung disease.  Similar
factors probably play a role in susceptibility to inhaled paniculate matter effects.
       By contrast experimental animals are bred as much as possible to be homogenous
genetically so  as to give great consistency in response. They are also usually studied in their
prime in regard to age and general health.  Presence  of disease is generally considered to be
a confounding factor to be stringently controlled in most animal paradigms.  As stated above,
those segments of the general population most affected from PM,0 exposure are the sick, the
very young, and the  old. Therefore the sensitivity of studies using relatively  small numbers
of healthy, genetically homogenous, laboratory animals who are in their prime is diminished
in exploring mechanism of paniculate matter effects.
3.     Heterogeneity of PM10 Composition
       Another key element helps to frame the discussion of the relevance of human clinical
studies and experimental animal work to establish a mechanism of action of paniculate  matter
in humans.  That is the issue of heterogeneity of both the composition of and exposure  to
paniculate matter. Paniculate matter  is a broad class of physically and chemically diverse
substances (as described in Chapter IV). The PM,0 fraction is composed of two distinct sub-
fraction of particle:  fine and coarse particles.   PM10 samplers collect all of the fine particles
-------
External Review Draft                                                     DO Not Quote or Cite
November 1995                              D-3
and a portion of the coarse ones.  There is a fundamental uncertainty regarding which
components or properties of particulate matter is essential to the observed effects in humans.
       Coarse particles are typically composed of re-suspended dusts from fields and streets
and may contain metal oxides of silica, aluminum, magnesium, titanium, and iron. Coal and
oil fly ash, calcium carbonate, sodium chloride, sea salt, small pollen, mold spores,  and
plant parts may also be present.  Fine particles are generally composed of sulfate, nitrate,
hydrogen ion, elemental carbon, organic compounds, biogenic organic compounds such as
terpenes, and metals such as iron, lead, cadmium, vanadium, nickel, copper, and zinc.
Some materials which are more typically found in the coarse fraction, may be also found the
fine  fraction.  Similarly, some materials typically found in the fine fraction may also be in
the coarse fraction due to particle growth in conditions of high relative humidity (e.g.,
sulfates).  Additionally, the properties of PM,0 vary greatly from place to place because of
differences in source mixes and atmospheric conditions.
       Thus unlike a typical experimental paradigm, where the agent to be studied is isolated
and the effects of exposure  described in well controlled studies, the heterogeneity of the PMj0
entity forces a different experimental approach. Typically constituents of the fraction are
tested individually to see if effects similar to those observed in humans are reproduced.
Consequently, animal studies are further weakened in regard to ability to  establish a
mechanism of action of particulate matter and to either refute or validate epidemiological
observation of effect in humans.
4.     Dosimetric Heterogeneity
       Finally, as discussed above in section V.A.I.,  dosimetric comparisons between
laboratory animals and humans, show that there are significant differences in the respiratory
architecture and ventilation of the two which adds additional complication to comparisons of
experimental and observed  data.  Ventilation differences coupled with differences in upper
airway respiratory tract structure and size, branching pattern, and structure of the lower
respiratory tract occur between species as  well as between healthy versus diseased states.
These differences may result in significantly different patterns of airflow affecting particle
deposition patterns in the respiratory tract (CD, Section  13).  Additionally, inter-species
-------
External Review Draft                                                      Do Not Quote or Cite
November 1995                              D-4
variability in regard to cell morphology, numbers, types, distribution, and functional
capabilities between animal and human respiratory tracks, leads to differences in clearance of
deposited particles which may in turn affect the potential for toxicity. (CD, Section 13).
Consequently the difficulty of using experimental animal data to investigate particulate matter
effects is further defined.
5.     Lack of Distinct Disease Pathology
       The background levels of cardiopulmonary disease as the cause of death for the
general population is very high.  Given  that COPD and heart diseases are frequent causes of
death, it is difficult to discern those who die from the additional effects of particulate matter
from those already  dying from such diseases and  to do autopsy to identify a specific
pathology associated with particulate matter caused mortality.  Even in historical studies
involving higher levels resulting in more pronounced effect it is hard to get an adequate
characterization of pathology related to particulate matter effects.  Thus without such a
characterization of the pathology of particulate matter induced mortality, development and
validation of appropriate models to study such effects are more difficult.
6.     Lack of Appropriate Equivalents to Epidemiological Endpoints
       Animal lexicological equivalents of such epidemiological endpoints as hospital
admissions and emergency  room visits as an indication of morbidity cannot be obtained.
Although mortality  can be recreated in a laboratory setting, the relevance of mechanism is
currently an issue.  In addition, there is question as to what the most appropriate measure of
particulate matter is in regard to its toxicity.  Specifically is it the inhalable mass which is
the most relevant metric of the toxic quantity of particulate matter or is it the number of
particles which reaches  specific targets?  Particles may have low inherent toxicity at one size,
yet greater potency at another (CD, Section 11).  A recent study by Chen et al. (1995)
confirmed that the number  of particles in the exposure atmosphere not just total mass
concentration is an  important factor in biological responses following acidic sulfate inhalation
(CD, Section 11).   Specifically, ultrafine particles with a diameter of 20 /xm have an
approximately 6 order of magnitude increased number than a 2.5 /*m diameter particle of the
-------
External Review Draft                                                    Do Not Quote or Cite
November 1995                              D-5
same mass concentration (CD, Section 11).  Comparisons of particle number and size are
shown in Table 11-1 of the CD.
      In addition to considerations of dose (inhalability and appropriate metric), the nature
of the response to particles and correlations of the appropriate response to susceptible
population are yet to be resolved.  Thus, identification of the dosimeter which induces
mortality and morbidity has not been elucidated with consequent difficulty interpretation and
design of controlled animal and human studies.
-------
                       APPENDIX E




Epidemiological Evidence of Short-term Exposure Mortality Effects
-------
> TABLE 12-4. SUMMARIES OF PUBLISHED PM10-ACUTE MORTALITY
3. EFFECTS STUDIES BASED ON VARIOUS PM MEASURES
VO
Ui
Health Outcome Synthesis Study
Total Mortality Ostro (1993)



Dockery and Pope
(1994)





to
i
^ Respiratory Mortality Dockery and Pope
(1994)

O
j> Cardiovascular Mortality Dockery and Pope
Jjj (1994)
D'
O
z
O
H
O
d
o
H
W
0


Location
London UK
Steubenville OH
Philadelphia PA
Santa Clara CA
St. Louis MO
Kingston TN
Birmingham AL
Utah Valley UT
Philadelphia PA
Detroit MI
Steubenville OH
Santa Clara CA

Birmingham AL
Utah Valley UT
Philadelphia PA
Santa Clara CA
Birmingham AL
Utah Valley UT
Philadelphia PA
Santa Clara CA










Original PM
Measurement
BS
TSP
TSP
COH
PM10
PM10
PM,0 (3d)
PM10 (5d)
TSP (2d)
TSP
TSP
COH

PM10 (3d)
PM10 (5d)
TSP (2d)
COH
PM10 (3d)
PM10 (5d)
TSP (2d)
COH










Mean
Equivalent PM10
80
61
42
37
28
30
48
47
40
48
61
35

48
47
40
35
48
47
40
35









Percent Change
Per 10 fig/m3
PM10 Equivalent
0.3
0.6
1.2
1.1
1.5
1.6
1.0
1.5
1.2
1.0
0.7
0.8

1.5
3.7
3.3
3.5
1.6
1.8
1.7
0.8










95 Percent
Confidence Interval
(0.29, 0.31)
(0.44, 0.84)
(0.96, 1.44)
(0.73, 1.51)
(0.1,2.9)
(-1.3.4.6)
(0.2, 1.5)
(0.9,2.1)
(0.7, 1.7)
(0.5, 1.6)
(0.4, 1.0)
(0.2, 1.5)

(-5.8, 9.4)
(0.7, 6.7)
(0.1, 6.6)
(1.5,5.6)
(-1.5, 3.7)
(0.4, 3.3)
(1.0,2.4)
(0.1, 1.6)









n
HH
3
-------
                      TABLE  12-3.  SUMMARIES OF RECENTLY PUBLISHED EPIDEMIOLOGICAL  STUDIES
                      RELATING HUMAN MORTALITY TO AMBIENT LEVELS OF PARTICIPATE  MATTER
            PM Measure
           (Concentrations)
                                        Study Description
                                                             Results and Comments
                                                    Reference
      KM (mc.in = 25;
      SD = 11)
                         Total, respiratory, and cardiovascular mortality in
                         Los Angeles County during 1970 to 1979 related to
                         O3, CO, SO2, NO2, HC, daily max. temperature,
                         relative humidity, and KM (a paniculate matter
                         metric of optical reflectance by particles, related  to
                         the ambient carbon concentration). Low pass filter
                         used to eliminate short-wave, so that only long-
                         wave associations are studied.
                                               Frequency domain analyses indicated significant
                                               short- and long-wave associations with KM. The
                                               filtered (i.e., long-wave) data analysis indicated that
                                               air pollution (including KM) was significantly
                                               associated with seasonal variations in LA mortality.
                                                Shumway et al.
                                                (1988)
K>
-U
OC
o
o
z
o
H
O
G
O
H
tn
o
JO
n
^^
H
tn
TSP (OECD Method)
(Lyons, France: 3 year
mean = 87 ,ug/m3}
(Marseilles, France
3 y mean =  126
BS
(mean =  90.1 jig/m3)
(24-h avg. daily max.
709 ;tg/m3)
Daily total, respiratory, and cardiac mortality for
persons  5:65 years of age tested for associations
with S02 and TSP during 1974 to 1976 in Lyons
and Marseilles, France.  Temperature also
considered in analyses.
Daily total mortality analyzed for associations with
BS, SO2, and H2SO4 in London, England, during
1963 to  1972 winters. Mean daily temperature and
relative humidity also considered.
No significant mortality associations found with TSP,
while SO2 was reportedly associated with total
elderly deaths in both cities.  Seasonally addressed
by analyzing deviations from 3-year average of
31-day running means of variables.  However, lags
of temperature not considered and probable seasonal
differences in winter/summer temperature-mortality
relationship not addressed.

PM,  SO2, and H2S04 all indicated as having
significant associations with mortality (0,  1 day lag).
Temperature also correlated (negatively) with
mortality, but with a 2-day lag.  Seasonally
addressed by studying only winters and by applying a
high-pass filter to the series and analyzing residuals.
                                                                                                                              Derriennic et al.
                                                                                                                              (1989)
Thurston et al.
(1989)
-------
                TABLE 12-3 (cont'd).  SUMMARIES OF RECENTLY PUBLISHED EPIDEMIOLOGICAL STUDIES
                     RELATING HUMAN MORTALITY TO AMBIENT LEVELS OF PARTICIPATE MATTER
           PM Measure
          (Concentrations)
             Study Description
            Results and Comments
                                                                                             Reference
     COH (monthly mean
     range = 9 to 12)
      BS
Daily total, respiratory, cancer, and circulatory
associations with daily COH in Santa Clara
County, CA, during 1980 to 1982 and 1984 to
1986 winters.  Daily mean temperature and
relative humidity at 4 PM also considered.

Daily total mortality in Athens, Greece, and
surrounding boroughs during 1975 to 1987
related to BS, SO2, NO2, O3, and CO2 using
multiple regression.
                                           An association found between COH and increased
                                           mortality, even after making adjustments for
                                           temperature, relative humidity, year, and
                                           seasonality.
                                           During winter months 1983 to 1987, the daily
                                           number of deaths was positively and statistically
                                           significantly associated with all pollutants, but the
                                           association was strongest with BS.
                                            Fairley (1990)
                                            Katsouyanni et al.
                                            (1990a)
to
      BS (annual mean range
      = 51.6to73.3/ig/m3)
      (maximum daily value
      = 790 jig/m3)
For the period 1975 to 1982 in Athens, Greece,
199 days with high SO2 (> 150 iigtm*) were
each matched on remperarure, year, season, day
of week, and holidays with two low SO2 days.
Mortality by-cause comparisons made between
groups by analysis of variance by randomized
blocks. BS correlated with SO2 at r  = 0.73, but
not directly employed in the analysis.
Mortality was generally higher on high SO2 days,
with the difference being most pronounced for
respiratory conditions. BS levels for each group
not provided, and BS-SO2 confounding not
addressed,  limiting interpretability of results.
                                                                                       Katsouyanni et al.
                                                                                       (1990b)
-------
XJ
a.
TABLE  12-3 (cont'd).  SUMMARIES OF RECENTLY PUBLISHED EPIDEMIOLOGICAL STUDIES
     RELATING HUMAN MORTALITY TO AMBIENT LEVELS OF PARTICIPATE MATTER
            PM Measure
          (Concentrations)
                           Study Description
             Results and Comments
                                                                                                                                Reference
      KM
      (mean = 25;
      SO -• 11)
             Shumway et al. (1988) 1970 to 1979 Los Angeles
             mortality dataset analyzed using a high-pass filter
             to allow investigation of short-wave (acute)
             associations with environmental variables (by
             removing seasonality effects).   Environmental
             variables considered in regression analyses
             included temperature, relative humidity,
             extinction coefficient, carbonaceous paniculate
             matter (KM), SO2>  NO2, CO, and O3.
Analyses demonstrated significant associations
between short-term variations in total mortality and
pollution, after controlling for temperature.  Day-
of-week effects found not to affect the
relationships.  The results demonstrated significant
mortality associations with O3 lagged 1 day, and
with temperature, NO2, CO,  and KM.  The latter
three pollutants were highly correlated with each
other, making it impossible to separately estimate
paniculate matter associations with mortality.
                                                                                                                         Kinney and Ozkaynak
                                                                                                                         (1991)
N>   TSP
tl*   (mean = 87 ng/m3)
     (24-h avg. range:
     46 to 137 /ig/m3,
     5th to 95th percentiles)
                              Total deaths in Detroit, MI,  1973 to 1982
                              analyzed using Poisson methods. Environmental
                              variables considered included TSP,  SO2, O3,
                              temperature, and dew point.  Seasonality
                              controlled via multiple dummy weather and  time
                              variables.
                                                          Significant associations reported between TSP and
                                                          mortality in autoregressive Poisson models (RR of
                                                          100 /ig/m3 TSP = 1.06).  However, most TSP
                                                          data estimated from visibility, which is best
                                                          correlated with the fine aerosol (and especially
                                                          sulfate) portion of the TSP. Thus, results suggest
                                                          a fine particle association.
                                              Schwartz (1991)
     TSP
     (mean  = 77 /ig/m3)
     (max.  -- 380 jig/m3)
     (5th to 95th percentiles
     37 to 132
             Total and cause specific daily mortality in
             Philadelphia, PA during 1973 to 1980 related to
             daily TSP and SO2 (n «2,700 days).  No other
             pollutants considered in the analysis. Poisson
             regression models, using GEE methods, included
             controls for year, season, temperature,  and
             humidity. Autocorrelation addressed via
             autoregressive terms in model.
Strongest associations found with pollution on the
same and prior days.  Total mortality (mean  =
48/day) estimated to increase 7% (95% C.I.  =
4 to 10%) for a 100 jig/m3 increase in TSP.
Cause-specific effects of TSP were larger (as %).
SO2 associations were non-significant in
simultaneous models with TSP, but correlations of
their coefficients not reported
                                                                                                                         Schwartz and Dockery
                                                                                                                         (1992a)
-------
                 TABLE 12-3 (cont'd).  SUMMARIES OF RECENTLY PUBLISHED EPIDEMIOLOGICAL STUDIES
                     RELATING HUMAN MORTALITY TO AMBIENT LEVELS OF PARTICIPATE MATTER
            PM Measure
           (Concentrations)
                                       Study Description
                                                        Results and Comments
                                                  Reference
to
O
O
'Z
G
O
H
W
      TSP
      (mean = 69 /tg/m3)
      (5th to 95th percentiles
      32 to 120 /tg/m3)
TSP
(mean = 111
(24-h avg. range:
36 to 209 ng/m3,
10th to 90th percentiles)
TSP
(mean =  113 /ig/m3)
(10th to 90th percentiles
 38 to 212 /ig/m3)
Age and cause-specific daily mortality in
Philadelphia, PA during 1973 and 1990 related
to daily TSP, SO2, and O3.  Other environmental
variables included were:  temperature,
barometric pressure, humidity, and precipitation.
Various  models employed, including poisson and
autoregessive. Prefiltering methods also applied
to remove long-waves in data.

Daily total mortality in Steubenville, OH,
between 1974 to 1984 related to TSP, SO2,
temperature, and dew point.  Poisson regression
employed, because of very low death counts/day
(mean = 3.1). Regressions controlled for
season by including dummy variables for winter
and spring, and autoregrcssive methods also used
to address any remaining autocorrelation.
Daily mortality in Steubenville, OH during 1974
to 1984 related to TSP, SO2, temperature, and
dew point (to allow comparisons of results with
Schwartz and Dockery, 1992b). Poisson method
employed.   Analyses  done overall and by-season.
TSP effect found only in winter season. TSP
never significant in by-cause analyses of those
< 15 or ^65 years of age. TSP effects
weakened by the addition of other pollutants
(TSP-SO2 r = 0.57).  However, the inclusion of
barometric pressure and precipitation in these
models may have acted as surrogates for PM,
potentially confounding results. Correlations
between TSP and these variables not presented.
In regressions controlling for season and
weather, previous day's TSP was a significant
predictor of daily mortality.  SO2 was less
significant in regressions, becoming
nonsignificant when entered simultaneous with
TSP.  Auto-regressive models gave similar
results.

In single pollutant models,  the TSP coefficient
was the same as Schwartz and Dockery (1992b),
but  TSP effects were found to be attenuated by
S02 inclusion in the model.  S02 was also
attenuated by the addition of TSP.  It is
concluded that TSP and SO2  effects cannot be
separated in this dataset. Intel-correlations
among these variables not presented.
                                                                                                                  Li and Roth (1995)
                                                                                                                        Schwartz and Dockery
                                                                                                                        (1992b)
Moolgavkar et al.
(1995)
n
-------
                 TABLE 12-3 (cont'd).  SUMMARIES OF RECENTLY PUBLISHED EPIDEMIOLOGICAL STUDIES
                      RELATING HUMAN MORTALITY TO AMBIENT LEVELS OF PARTICIPATE MATTER
          PM Measure
        (Concentrations)
                                      Study Description
                                                                     Results and Comments
                                                     Reference
RS
(mean =
90. 1 ;
-------
vo
vo
                 TABLE 12-3 (cont'd).  SUMMARIES OF RECENTLY PUBLISHED EPIDEMIOLOGICAL STUDIES
                     RELATING HUMAN MORTALITY TO AMBIENT LEVELS OF PARTICULATE MATTER
   PM Measure
  (Concentrations)
                                          Study Description
                                                                   Results and Comments
                                                        Reference
      TSP
      (mean = 52 jug/m3;
      SD = 19.6
                    Daily total and cause-specific mortality in Cincinnati,
                    OH, (mean total = 21/day) during 1977 to 1982
                    related to TSP,  temperature, and dew point. Poisson
                    model employed with dummy variables  for each month
                    and for eight (unspecified) categories of temperature
                    and dew point.  Linear and quadratic time trend terms
                    also included. Spline and nonparametric models also
                    applied.  Autocorrelation not directly addressed.
                                                  TSP was significantly associated with increased risk of total
                                                  mortality.  The relative risk was higher for the elderly and
                                                  for those dying of pneumonia and cardiovascular disease.
                                                  However, the analysis failed to consider other pollutants,
                                                  and there remains the potential for within-month, long-wave
                                                  confoundings.
                                                       Schwartz
                                                       (1994a)
U)
TSP
(mean  =
375 fig/m3)
(maximum
1,003
PM)0
(mean = 47
(24 h max.
365 ,ig/m3)
(5 day max.
297 ,zg/m3)
                 jtg/m3)
Daily deaths during 1989 in two residential areas in
Beijing, China, (mean total deaths = 21.6/day) related
to TSP and S02 using Poisson methods. Controlling
indicator variables for quintiles of temperature and
humidity, as well as for Sunday also included.
Long-wave confounding and autocorrelation not
directly addressed.  However, season-specific results
presented.
Total, respiratory, and cardiovascular mortality in
Utah County, UT, during 1985 to 1989 related to
5-day moving average PM)0, temperature, and
humidity.  Time trend and a random year terms also
included in autoregressive Poisson models employed.
Seasonally not directly addressed in this basic model,
but the addition of four seasonal dummy variables
changed results little.
Significant mortality associations found for In (S02) and In    Xu et al.
(TSP). Associations were strongest for chronic respiratory    (1994)
diseases.  In simultaneous regressions, SO2 was significant,
but not TSP.  However, the two pollutants were highly
correlated with each other (r = 0.6), as well as with
temperature.  In season-specific analyses, both pollutants
were significant in summer, but only SO2 in winter.

A significant positive association between total non-          Pope et al.
accidental mortality and PM,0 was observed, the strongest    (1992)
association being with the 5-day moving average of PM10.
The association was largest for respiratory disease, the next
largest for cardiovascular, and the lowest for all other.
Association noted below 150 jig/m3 PM10. The possible
influence of other pollutants discussed, but not directly
addressed.
-------
 D.
 \o
TABLE 12-3 (cont'd). SUMMARIES OF RECENTLY PUBLISHED EPIDEMIOLOGICAL STUDIES
     RELATING  HUMAN MORTALITY TO AMBIENT LEVELS OF PARTICIPATE MATTER
            PM Measure
          (Concentrations)
                           Study Description
             Results and Comments
                                                                                                                         Reference
      PM
         10
      St. Louis, MO:
      (mean = 28 ^g/m3)
      (24 hr max.  = 97 /tg/m3)
      Kingston/Harriman, TN
      (mean = 30 /ig/m3)
      (24 h max. = 67
             Total mortality in St.  Louis, MO, and
             Kingston/Harriman, TN (and surrounding
             counties), during September 1985 to August 1986
             related to PM)0>  PM2 5, SO2, N02, O3, H + ,
             temperature, dew point, and season using auto-
             regressive Poisson models.
Statistically significant daily mortality associations
found with PM10 and PM2 5 in St. Louis, but not
with other pollutants.  In Kingston/Harriman, PM10
and PM2 5 approached significance, while other
pollutants did not.  Seasonality was reduced by
season indicator, variables, but within season long
wave cycles not directly addressed.
                                                                                                                    Dockery et al.
                                                                                                                    (1992)
      PM10
      (mean = 48 /*g/m3)
      (24 h max. = 163 A 150
             employed addressed seasonal long wave influences /ig/m3. However, the possible role of other
             by the inclusion of 24 sine and cosine terms having pollutants not evaluated.
             periods ranging from  1 mo to 2 years.
             Autoregressive linear  models also applied.
D
O
2
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O
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O
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m
o
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m
PMIO
(mean = 40
(24 h max. = 96
             Total, cardiovascular, cancer, and respiratory
             mortality in Toronto, Canada, during 1972 to 1990
             related to PM10, TSP, SO4, CO, O3, temperature,
             and relative humidity.  Nineteen-day moving
             average filtered data used in OLS regressions.
             Sixty-three hundred and three PM10 values
             estimated based on TSP, S04, COH, visibility
             (Bex() and  temperature data, using model developed
             from 200 PM,0 sampling days during the period.
Significant associations found between all pollutants
considered and mortality, after controlling for
weather and long wave influences.  However, it was
not possible to separate the PM10 association from
other paniculate measures considered. Simultaneous
PM and ozone regressions gave significant
coefficients for each, but intercorrelations among the
pollutants not  presented.
                                                                                                                          Ozkaynak et al.
                                                                                                                          (1994)
-------
 O
 O
 Z
 O
 H
O
n
H
m
                TABLE 12-3 (cont'd).  SUMMARIES OF RECENTLY PUBLISHED EPIDEMIOLOGICAL STUDIES
                     RELATING HUMAN MORTALITY TO AMBIENT LEVELS OF PARTICIPATE MATTER
           PM Measure
         (Concentrations)
                 Study Description
              Results and Comments
 Reference
     PM
         10
     (mean = 58 /*g/m3)
     (24 h max.  =
     177  i/m3)
Total mortality in Los Angeles, CA, during 1985 to 1990
related to PM,0, O3, CO, temperature, and relative
humidity. Poisson models employed addressed seasonal
long-wave influences by including multiple sine and cosine
terms ranging from 1 mo to 2 years in periodicity. OLS
and long linear models also tested. Winter and summer
analyzed separately also.
Association between PMj0 and mortality found to be
only mildly sensitive to modeling method.  CO also
individually significant. The addition of either CO or
03 lowered the significance of PM10 in model
somewhat, but the PM10 coefficient was not as
affected, indicating minimal effects on the PM10
association by other pollutants in this case.
Kinney et
al. (1995)
to
      PM10
      (mean = 38
      (24 h max.
      128 /zg/m3)
Total mortality in Los Angeles, CA and Chicago, IL
during  1985 through 1990 related to PM10, O3, and
temperature.  Analysis focused on importance of monitor
choice to modeling results. Poisson models used
addressed seasonal long wave influences by  including
multiple sine/cosine terms ranging from 1 mo to 2 years
in periodicity.
Average of multiple sites' PM10 found to be
significantly associated with mortality in each city after
controlling for season, temperature and ozone.  Other
pollutants and relative humidity not yet considered.
Individual sites' PM10 varied from non-significant to
strongly significant. Also, dividing the data by season
diminished the significance of the multi-site average
PM10 in mortality regressions.  Both site selection and
sample size concluded to influence results.
Ito et al.
(1995)
-------
VO
\O
                 TABLE 12-3 (cont'd). SUMMARIES OF RECENTLY PUBLISHED EPIDEMIOLOGICAL STUDIES
                      RELATING HUMAN MORTALITY TO AMBIENT LEVELS OF PARTICIPATE MATTER
    PM Measure
   (Concentrations)
                                             Study Description
                                                                   Results and Comments
                                                   Reference
to
      PMIO
      (mean =  115
      (24 h max.
      367 /ig/nv,)
PM10
(mean = 82.4 /ig/m3)
(24 h avg. SE =
38.9 fig/m3)
Total, respiratory, and cardiovascular daily deaths/day
(means = 55, 8,  and  18, respectively) in Santiago, Chili
during 1989 through 1991 related to PM10, O3, SO2, NO2,
temperature and humidity. Seasonal influences addressed
by various methods, including seasonal stratification, the
inclusion of sine/cosine terms for 2.4, 3, 4, 6, and 12
month periodicities, prefiltering, and the use of a
nonparametric fit of temperature. Log of PM10 modeled
using OLS with first order autoregressive terms.
Respiratory mortality  among children < 5 years old
(mean = 3/day) in Sao Paulo, Brazil during May 1990
through April 1991 related to PM10, SO2, NOX, O3, CO,
temperature, humidity, and day of week. Season
addressed by including seasonal and monthly dummy
variables in regressions.   Mortality data adjusted for non-
normality via a square root transformation.
Significant association found between PMto and daily   Ostro et al.
mortality, even after addressing potential confounders   (1995a)
(e.g., weather), other pollutants, lag structure, and
outliers. Strongest associations found for respiratory
deaths.  S02 and NO2 also significantly associated
individually, but only PM10 remained  significant
when all were added simultaneously to the
regression.  Correlations of the coefficients not
reported.
Significant association found between  respiratory       Saldiva et al.
deaths and NOX, but no other pollutants.  No such     (1994)
association found for non-respiratory deaths.
However, auto-correlation not addressed.   Also,
inter-correlations of the pollutant coefficients not
reported (but NOX - PM10 correlation  = 0.68)
      PM
 0
 O
 o
 H
O
 G
 O
 H
 m
         10
                     Total mortality among the elderly (^65 years old)
(mean =  82.4 /ig/m3)  (mean = 63/day) in Sao Paulo, Brazil during May 1990
(24 h avg. SE =
38.9 /lg/m3)
through April 1991  related to two day avg. of PM10, S02,
NOX, O3, and CO, and to temperature, humidity, and day
of week.  Season addressed by  including seasonal and
monthly dummy variables.  Temperature addressed using
three discrete dummy variables.
Significant associations found between total elderly     Saldiva et al.
deaths and all pollutants considered.  In a             (1994)
simultaneous regression, PM10 was the only pollutant
which remained significant.  The PM10 coefficient
actually increased in this regression, suggesting
interpollutant interactions.  Correlations of the
pollutant coefficients not provided.
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I— I
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                TABLE 12-3 (cont'd). SUMMARIES OF RECENTLY PUBLISHED EPIDEMIOLOGICAL STUDIES
                     RELATING HUMAN MORTALITY TO AMBIENT LEVELS OF PARTICIPATE MATTER
         PM Measure
        (Concentrations)
                  Study Description
             Results and Comments
  Reference
      PM10 (Cook County
      median = 37 /xg/m3;
      max = 365 /*g/m3)
      (Salt Lake County
      median = 35 /*g/m3;
      max = 487 jig/m3)
Total, respiratory, circulatory, and cancer mortality in
Cook County, 1985 to 1990.  Elderly, total by race and
sex also evaluated. Poisson regression with seasonal
adjustments, meteorological variables, and  pollen tested.
In Salt Lake Count, total and elderly mortality. One daily
station in Cook County and two daily monitoring stations
in Salt Lake County,  plus multiple	-day stations.
Average and single site PMi0 were significant
predictions of PM,0 in Cook County for total,
elderly, cancer, and elderly white mortality, marginal
for respiratory, circulatory, and elderly black.
Significant Fall and Spring mortality in Cook
County, not Summer or Winter. No significant
effects in Salt Lake County. No copollutants.
Styer et al.
(1995)
to
      PM10 (variable by
      month and year)
Reanalysis of Utah County mortality, 1985 to 1992,
broken down by year, season cause and place of death.
PM10 was entered as a dichotomous variable, less or
greater than 50 ^g/m3.  No adjustment for copollutants or
for weather in Poisson regression, except for daily
minimum temperature.  Poisson regression, not GEE.
Variations in RR did not appear to be associated with  Lyon et al.
high or low PM10 days. High RR for cancer deaths,   (1995)
age < 60, at home. Highest RR in spring.
Increased RR for sudden infant death syndrome.
Patterns appear noncausal.
-------
             APPENDIX F




Miscellaneous Tables of Effects Information
-------
TABLE 11-2. CONTROLLED HUMAN EXPOSURES TO ACID AEROSOLS AND OTHER PARTICLES
l~»
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Ref. Subjects Exposures' MMAD2 GSD3
Anderson et 15 healthy 1): air
al. (1992) 15 asthmatic 2): H^C^ • 100 /ig/m3 1.0 2
18 to 45 years 3): carbon black
»200>ig/nr'
4): acid-coated carbon
with » 100 pg/m3 H2SO4
Aris et al. 19 asthmatic Mouthpiece study:
(1990) 20 to 40 years HMSA3 0 to 1000 /iM + ft j
H2SO4 50 fM vs H2SO4 50
/iM
Chamber study: ^
HMSA 1 mM + HjSC^
5 mM vs H2SO4 5 mM
Aris et al. 10 healthy HNOj 500 fig/m3 or H2O, or =6
( 1 99 1 a) nonsmokers 2 1 air followed by ozone 0.2
to 31 years ppm
ozone sensitive



Aris et al. 18 asthmatics Mouthpiece study:
( 1 99 1 b) 23 to 37 years HjSO, v» NaCI. 0.4 vs « 6
• 3000 fig/m3 with varying
particle size, osmolarity,
relative humidity

Chamber study: H2SO4 vs
NaCI, 960 to 1400 fig/m3 fi
with varying water content









Duration Exercise Temp RH4 Symptoms Lung Function Other Effects
'C %
60 min. VF = 50 22 50 Healthy subjects Largest No change in
L/min more decrements in airway
symptomatic in FVC with air responsiveness
air. exposure.


100 Won 100 HMSA did not No effects on
cycle increase SRaw6
symptoms in
comparison with
, h .25 H'S°< al0ne'


2h 50 min of 22 100 No effects of No direct effects No change in
each h fog exposure of fog exposures, airway
40 L/min Greatest responsiveness
decrements when
ozone preceded
„ ,_ by air.
22 50 '
No effects Increases in SRaw
. , . .... . . with low RH
16 mm With & .. .
... . conditions; no
without „. .- „ . .
• 24 <10vs pollutant-related
exercise. *"L
100 effects

100 Won
1 h cycle =27









Comments
Smoking
status of
subjects not
stated.









Fog may
have
reduced
ozone
effects on
lung
function.
Postulated
that effects
seen in other
studies due
to secretions
or effects on
larynx










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TABLE 11-2 (CONT'D). CONTROLLED HUMAN EXPOSURES TO ACID AEROSOLS AND OTHER PARTICLES

Rrf Subjects
Avol ei al ?1 healthy
(liSS;!) 2\ asthmatic
18 to •)? years




Avol et al. 22 healthy
(!088b) 27. asthmatic
18 to 45 years





Avol et al. 32 asthmatics
(1000) 3 to 16 years




Balmes et 12 asthmatics
al. (1088) responsive to
hypcosmolar
saline aerosol
25 to 41 years











Temp
Exposures1 MMAD2 GSD3 Duration Exercise 'C
Air 0.85to 2.4 to Ih 10 min X 3 21
HjSO4: 0.91 2.5 47 to
Healthy: 363. 40 L/min
1128. 1578
Asthmatic: 396,
999. 1.460
rt'm,
H2O 9.7 to 10.7 1 h 10 min X 3 9
HjSO4: 41 to 46
Healthy: 647. L/min
1.100,2,193
pg/nr1
Asthmatic: 516,
1,085,2,034
Mg/mj
Air 40 min 30 min rest, 21
HjSO446. 127, 0.5 1.9 10 min
and 134 /jg/nr1 exercise
20L/min;m2


Mouthpiece, At rest =23
5.900to
yj.lOOptaf:
NaCl 30 mOsm
HjSO430mOsm -5 to 6 1.5
HNOj 30 mOsm
HjSO4+HN0330
fflOsin
H2SO4 300 mOsm








RH4 Symptoms Lung Function Other Effects
50 Healthy: Slight Healthy: No
increase in cough with effects on hing
highest function or
concentrations. airway reactivity.
Asthma: dose-related Asthma: 1FEV,
increase in lower 0.26 L with
resp. sx. H2SO4 1.460
100 Dose-related increase Healthy: No No effects on
in lower resp. sx. in effects on lung airway
both groups. function. responsiveness

Asthma: tpeak
flow 16% at
2.034 fig/m1
H2S04 .
48 No pollutant effect No pollutant
effect.
One subject
increased SRaw
14.2% with acid
exposure.
Concentration of
acid aerosol
required to
increase SRaw by
100% lower than
forNaCl. No
difference
between acid
species.








Comments







Half the subjects
received acidic
gargle; no
difference in
effects.



Did not
reproduce
findings of
Koeniget al..
1983.

Exposures did
not mimic
environmental
conditions. No
mitigation by
oral ammonia.










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TABLE tl-2 (CONTD). CONTROLLED HUMAN EXPOSURES TO ACID AEROSOLS AND OTHER PARTICLES

Ref. Subjects
Culpctal. 16 healthy
(1995) 20 to 3° yrs




Fine ct al. 8 asthmatics
(19876) 22to29yrs




Fine et al. 10 asthmatics
(1987a) 22 to 34 yrs




Framptonet 12 healthy
al. (1992) 20to39yrs





Frampton et 30 healthy
al. (1995) 30 asthmatics
20 to 42 yrs





Green el al. 24 healthy
(1989) 18 to 35 yrs







Temp
Exposures1 MMAD2 GSD3 Duration Exercise 'C
N»CllOOO/ig/m3 0.9 1.9 2h IOminX4 22
H2SO4 =40 L/min
l.OOOMg/m3



Mouthpiece: 5.3 to 6.2 1.6 to At rest
Buffered and 1-8
unbuffered HC1
•nd
-------
p TABLE 11-2 (CONT'D). CONTROLLED HUMAN EXPOSURES TO ACID AEROSOLS AND OTHER PARTICLES
o
O"
— • H.inlev et
5* al (1'W;)
i—
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Koenig ct
3\ (I9R9)



Koenig et
al (1902)

H- *
I
t— *

Koenig ct
al (1 093)


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Subjects Exposures'
22 asthmatics Mouthpiece:
12 H) 19 yrs 5): Air;
H2SO470, 130fig/m3
2): Air;
H2SO4 70 pg/m3
with and without lemonade


9 asthmatics with Mouthpiece:
exercise-induced Air;
hrnncho-spasm HjSO4 68 fig/m3:
12 to 18 yrs SOjO.l ppm;
HNOj 0.05 ppm
14 astlimatics with Mouthpiece:
exercise-induced Air;
tironcho-spasm H3SO4 35 or 70 |ug/m'
1 3 to 18 yrs



R healthy Mouthpiece:
9 asthmatic Air;
60 to 76 yrs (Nfty^SO^ «70 fig/m3;
H,SO4 -74 to 82 f
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TABLE 11-2 (CONT'D). CONTROLLED HUMAN EXPOSURES TO ACID AEROSOLS AND OTHER PARTICLES
Ref.
Koenig et
al. (1994)








Kulle et al.
(1986)



Laube et al.
(1993)









Linn et al.
(1989)



Linn et al.
(1994)







Subjects
28
asthmatics
12 to 19 yrs







20 healthy
20 to 35 yrs



7 healthy
20 to 31 yrs









22 healthy
19 asthmatic
18 to 48 yrs


15 healthy
30 asthmatic
18 to 50 yrs






Exposures1 MMAD2
Mouthpiece:
Air;
ozone 0.12 ppm+NOj 0.6
0.3 ppm;
ozone 0.12 ppm+NOj
0.3 ppm+HjSO4
68 fig/m •
ozone 0.12 ppm+NOj
0.3 ppm+HNOj
0.05 ppm
Air. activated carbon 517 1 .5
pglttP; SOj 0.99 ppm;
carbon 517 fig/m3 +
SO2 0.99 ppm.

Head dome:
NaCI -SOOpg/m3 10.3
H2SO4 » 500 jig/m3 10.9








H2O 20
H2S04 -2,000 /ig/m3 10
1


Air;
ozone 0.12 ppm; »0.5
H2SO4 lOOpg/m3'
ozone +H2S04





Temp
GSD3 Duration Exercise 'C RH4 Symptoms
90 min X VE 3 X 22 65 No pollutant
2 days resting effects
1.5







1.5 4h 15 minx 2, 22 60 No
35 L/min symptoms
related to
carbon
exposure
1 h 20 min 22 to 25 99 No pollutant
effects









Ih 40 to 45 «10 74 to Increased
L/min 100 total score
with larger
acid
particles.
6.5 h/dX 2 50 min X 6 21 50 Symptoms
-2 d 29 L/min unrelated to
atmosphere






Lung Function
No pollutant effects









No direct or additive
effects of carbon
exposure


No pollutant effects










No pollutant effects




IFEV, AFVCin
ozone, similar for
healthy & asthmatic
subjects. Greater fall in
FEV, for acid + ozone
than ozone alone,
marginally significant
interaction.

Other Effects
No effects on
airway
responsiveness












Trachea!
clearance
increased
(4/4 subjects).
Outer zone
clearance
increased
(6/7 subjects).
No effects on
airway
responsiveness
No effects on
airway
reactivity


Increased
airway
responsiveness
with ozone.
marginal
further
increase with
ozone + acid

Comments
6 subjects with
moderate or
severe asthma did
not complete
protocol





















4 asthmatic
subjects unable to
complete
exposures because
of symptoms.
Avenge subject
lost 100 ml FEV,
with ozone, 189
ml with
ozone -(-acid

Original findings
replicated in
13 subjects
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t— »
TABLE 11-2 (CONT'D). CONTROLLED/ HUMAN EXPOSURES TO
Rrf Subjects
Morrow ei si. 1? asthmatic
'IW-U ?0 tn 57 yrs
_V to ,'i! yrs


I'tcll rt ,il 15 asthmatic
(1W) 19 to 50 yrs
Yang and 30 healthy
Yang(l9i5SO4, tow NH3
Mouthpiece: Bagged
polluted air.
TSP = 202 f.g/m3

Temp
Duration Exercise 'C
2h Asthmatics: 21
10 min X 4
COPD: 7 min
X 1


30 min 10 min
VF3X
resting
?0 min At res!

ACID AEROSOLS AND OTHER PARTICLES
RH4 Symptoms Lung Function
30 No pollutant Asthmatics:
effects. iFEV, slightly
greater after acid
than after NaCI.
COPD: No
effects.
20 to 25 Greater fall in
FEV, with low
NH3(l9%)than
with high NH3
(8%).
Healthy subjects:
no change
Asthmatics:
IFEV, «756

Other Effects




Increased airway
responsiveness
in asthmatics
reported; no
allowance for
change in
airway caliber
Commeno




No control
exposure

'Exposures in environmental chamber unless otherwise stated.
2Mass median aerodynamic diameter.  In some studies expressed as volume median diameter; see test.
'Geometric standard deviation.
4Relative humidity.
'Hydroxyme thane sulfonic acid.
'Specific airways resistance.
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                                    TABLE  5-2.   POSSIBLE RESPONSES TO PARTICLE DEPOSITION IN THE  RESPIRATORY TRACT
     Principal
Region of Deposition
fxtralhorAcfc (ET)
Tracheobronchial (TD)
Potential  Mechanisms
Chemical and mechanical  irritation/stimulation of receptors by
deposited material
                              Slowed,  stopped Mucocillary clearance by wood dust
                              (Schleslnqer  and Llppmann. 1970)
                              Enhanced deposition at larynx  (Sehlesinger and Llppmann, 1976)
Chemical  and mechanical  irritation/stimulation resulting In
bronchoconstrlction (Wlddlcombe  et  aK,  1962; Made). 1973) by:

."Inert"  dusts (granulated  charcoal, coal dust, carbon dust,
 calcium  carbonate, carbon  impregnated plastic, iron
 hydroxide; Widdtcombe et al., 1962; Dubols and Dautrebande,
 1958; Andersen et aK ,1979; Constantine et al.,  1959)
.Resuspended urban dust (crustal materials, sulfates,
 volatiles; Toyama, 1964)
.Coarse organic dusts, aeroallergens (grain dusts, pollens,
 mold, etc.  e.g.i Dosman.  1980)
.Fine acid aerosols (sulfuric acid, ammonium btsulfate;
 Utell et aKt 1981)
.ConmunTFy air pollution with moderately high PH  (Lebowttz
 ct al.,  1974)
.Ffne particles in combination with pollutant gases (SO.;
 Koentg et aJL, 1981;  HcJilton et aj_., 1976)           '
                              Enhanced sensitivity to subsequent bronchoconstrie live
                              agents by sulfuric acid (Utell et a_K. 1981)
                              Altered  clearance  rates,  Increased mucous  production by
                              deposited material  (cigarette  smoke,  sulfuric acid, dusts)
                              (Llppmann et  aK,  1981; Camner et, aK,  1973)
                              Direct damage  to  tissues by acid aerosols
                              Increased deposition at bronchial bifurcations  (Bell and
                              Frledlander,  1973), slower clearance  (Hildlng.  1957)
                              Interaction of carcinogens and ambient particles
Potential Consequences/Observations
Symptomatic Effects:
-Oryness In nose, mouth, and throat (polymerized dust
 containing carbon black, Andersen et a_K, 1979)
-Sneezing, rhinitis (pollen), (MIcheT et aK, 1977)
                                                                Nasal cancer (wood workers. NAS,1977a,p. 15M)
                                                                Laryngeal cancer (cigarette smoke, NAi, 1977a, p. 150)
Reduced respiratory function

Enhanced breathing difficulties or other acute aggravation
of heart and lung disease, including:

-Asthma (Smith and Paulus, 1971)
-Bronchitis (Lawther et a_K. 1970)
-Emphysema and cardiovascular disease (Martin and
< Bradley. 1960)
-Influenza (sodium nitrate, Utell ejl aK, 1980)

Enhanced deposition of fine and coarse particles
(Albert et aK.  1973)
                                                                As above
                                                                 Possible  promotion of  bronchitis by repeated exposure
                                                                 to  sulfuric  acid  (Llppmann et  a_K, 1981)
                                                                 -Increased bronchitis  prevalence In people exposed to
                                                                  community air  pollution  (Holland et al., 1969;
                                                                  Holland  and Reid, 1965)
                                                                 -Increased bronchitis  prevalence In workers exposed
                                                                  to coal  dust,  other dusts (Morgan, 1978)
                                                                 Bronchial  lesions  (Alarie   et^aj,.,  1975)
                                                                 S1te
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                                    TABLE 5-2.  POSSIBLE RESPONSES TO PARTICLE  DEPOSITION IN THE RESPIRATORY TRACT
                                                                    (CONTINUED)
     Principal
Region of Deposition
Pulmonary (Alveolar, AL)
Thoracic, not specific
to TB, AL
Potential Mechanisms
Decreased oxygen transport and probable increased  resistance
of blood flow through pulmonary capillaries
                              Death of macrophages resulting in  release of proteolytlc
                              enzymes that damage alveolar tissues,  by silica, other
                              coarse dusts (Zlskind et aj_.,  1976)
                              Damage to macrophages,  other  host defense mechanisms by
                              surface coating of toxic  materials  (Camner et al., 1974a;
                              Aranyi et al.,  1979)                       ~~ ~

                              Damage to tissues by  acid aerosols
                              Combined effect of exposure and slow clearance of particles
                              (Pratt and K11 burn.  1971)
Possible effects on host  mechanisms (clearance, Immunology)
promoting Infection
                              Successive measurements of respiratory function suggest
                              damage  to the  lung during childhood may be  produced by
                              infection (Speizer et ah, 1980)
                              Absorption of systemic toxicants  (e.g. pesticides, trace
                              elements, carcinogens) resulting  in  extra-respfratory
                              effects.  Absorption efficiency greatest for alveolar
                              deposition
 Potential Conseouencpt/nh
 Aggravation of cardio-pulmonary disease associated
                                                                Increased susceptibility to  infection

                                                                ~taeS"5i TtalUy 1" Jnfected m1ce "posed
                                                                 to Cd, Ni. Hn aerosols (Gardner 1981-
                                                                 Graham etai., 1978;  AdUns eta. {979  1Mtn
                                                                -Loss  of alveolar  surface areriVwhvse™"  ?„ ^ *
                                                                 exposed to H2S04  (Hyde et al!t 1978)      '      °9S
                                                                Accumulation of pigment In  lungs from inhaled
                                                                particulate matter (Pratt and  Kilburn. 1971;
                                                                Sweet et al_., 1978)

                                                                Possible role of community  air pollution In
                                                                emphysema (Ishikawa e_t a^.,  1969)
Increased lower respiratory tract infection  in
children with increased BS+SO  exposure (Donnl
and Waller. 1966; Lunn et al..; 1967)

Increased influenza rates ("Dust"; Kalpazanov
CC pl.t 19/D)
                                                               Persistent changes In airways In those children
                                                               with higher Infection rates previously exposed
                                                               to particulate matter (Colley et al., 1973;
                                                               Klernan et al., 1976)
                                                                                                effects of

                                                               Gastro-intestinal cancer (Winklestein and Kantor,
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TABLE 5-3.  SENSITIVE POPULATION SUBGROUPS
Subgroup
Individuals with
chronic
obstructive
pulmonary diseases
. Bronchitis
. 6ronch1ectas1s
. Emphysema
Individuals with
cardiovascular
disease
Individuals with
Influenza
Asthmatics
Clderly
Children
Smokers
touth or oronasal
breathers
Population Estimates
7,800,000 (DHEU, 1973)
16,100,000 (DOC, 1980)
Unknown
6,000,000 (DHEW, 1973)
24.658.000
>65 years old
(DOC, 1980)
46,300.000
>14 years old
(DOC, 1980)
50,000,000 {DHEW, 1977)
15X of population
(Nllnlmaa et al., 1981;
Salbene et al., 1978)
Rationale (or Criteria)
-Mucus hypersecretlbn and blocked
airways may predispose Individuals to
bronc'hospasm
-Enlarged airspaces Increase blood
flow resistance through the pulmonary
papillary network. Increasing cardiac
stress
-Enhanced sensitivity to difficulties
in breathing
-Increased sensitivity of respiratory
epithelium (Utell et, a_K, 1980)
-Hyperreactlve airways (Boushey et al.,
19801 .
-Reduced lung elasticity (Cotes, 1979)
-Immunologlcally deficient
-Immunologlcal Immaturity .Imolles
diminished protection (Elsen, 1976)
-Childhood respiratory Infection might
prevent the .lungs from reaching their
full size at maturity (Bouhuys, 1977;
Spelzer et al., 1980)
-Ch11dren~Tlk~?1y to spend a greater
amount of. time outdoors and to be
more active. Probably higher venti-
lation rates and thus, Increased
Inhalation of pollutants.
-Urban lung cancer In smokers greater
(Doll, 1978)
-Combinations of PM and carcinogens
may enhance response
-Increased tracheobronchlal. deposition
(Albert et al., 1973)
-Increased particle penetration (CD,
p. 11-20)
Observational/Associations Supporting Increased Sensitivity
Many of the deaths and Illnesses during and after air pollu-
tion episodes were among people with pre-existing obstructive
diseases (Ministry of Health, 1954; Martin, 1964;
Lawther §!§]_., 1970; Martin and Bradley, 1960)
Many deaths and hospital Izatlons during pollution episodes
among cardiovascular patients (Ministry of Health, U.K.,
1954; Martin, 1964)
Influenza patients were more sensitive to NaNO, during their
period of sickness (Utell et al., 1980). J
Highest mortality during Influenza epidemic on days with
highest PM. (Martin and Bradlev. 19601.
Su If uric acid enhanced response to bronchoconstrlctlve agent
In asthmatics, not In normals (Utell et al., 1981)
-Many of the deaths and Illnesses during air pollution
episodes were among elderly (Ministry of Health,
1954; Martin and Bradley. 1960: Greenburg et al.. 1962).
-Increased acute respiratory disease with high particles,
SOX (Lebowltz et al., 1972; Douglas and Waller, 1966)
-Effects of acute respiratory disease acquired during child-
hood persisted until adolescence or young adulthood
(Colley eial., 1973; Klernan et al., 1976).
-Frequency of respiratory symptoms and diseases greater In
smokers exposed to same occupational or community pollution
as non-smokers (Lambert and Reid, 1970: '"'iSH, 1976).


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