AIR
POLLUTION
INDICES
A Compendium
and Assessment
of Indices
Used In the
United States
and Canada
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A O
AIR POLLUTION INDICES
A Compendium and Assessment
of
Indices Used in the United States and Canada
Gary C. Thorn
and
Wayne R. Ott
December 1975
Sponsored by
The Council on Environmental Quality
and
The U.S. Environmental Protection Agency
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FOREWORD
The American public needs to be provided with
accurate, timely, and understandable information about
air quality conditions in the nation’s cities. Aware-
ness of the daily level of urban air pollution is often
important to those who suffer from illnesses which are
aggravated or caused by air pollution, as well as to the
general public. Many inericans who live or work in urban
areas can voluntarily modify their activities at times
when they are cognizant of high air pollution levels.
Further, the success of the nation’s commitment to
improving air quality may depend upon the support of
citizens who are well-informed about local and nation-
wide air pollution problems and the progress of abatement
efforts.
In recent years, dozens of states and municipalities
throughout the United States and Canada have responded to
these public information needs by developing or adopting
various kinds of air pollution indices for daily reporting.
The news media have widely adopted these indices, and the
result has been that most of the air quality information
now provided to the general public is communicated in the
form of an air quality index. Thus, there now exists a
wealth of experience in using air pollution indices for
public reporting.
This report draws upon that experience to summarize
and assess the many air pollution indices that are regularly
being used to communicate air quality information to citizens
of the United States and Canada. The first comprehensive
study of its kind, this compendium and assessment was per-
formed by Gary C. Thom, a consultant to the Council on
Environmental Quality, and Wayne R. Ott of the U.S.
Environmental Protection Agency’s Office of Research and
Development. The study was conducted in response to recent
recommendations of the National Academy of Sciences and the
Congressional Research Service that CEQ, EPA, and other
Federal agencies should increase the efforts devoted to
developing and utilizing better air quality indicators
for public information. The contributions of many state
and municipal agency personnel were invaluable to the
Success of the study.
iii
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The findings of this study are quite disturbing.
The report describes a confusing and scientifically
inconsistent array of air quality reporting methods in
use today. At least 15 basically different kinds of
indices are used, and few of them seem to provide truly
meaningful information to the public.
As a result of this study, the Council on Environmental
Quality established a Federal Interagency Task Force on
Air Quality Indicators in the summer of 1975. The primary
mission of the task force is to develop a standard air
pollution index which the participating Federal agencies
can recommend for nationwide use. The task force consists
of CEQ. the U.S. Environmental Protection Agency, and the
National Bureau of Standards, the National Oceanic and
Atmospheric Administration, and the Office of Environmental
Affairs of the Department of Commerce.
Appendices E and F of this report describe two of the
air pollution indices which are being actively considered
by the task force: the Standardized Urban Air Quality
Index and the Primary Standards Index. Although neither
of these indices has yet received the endorsement of the
task force, both of them were developed by CEQ and EPA
personnel who were cognizant of the findings of this
compendium and assessment of U.S. and Canadian air pollu-
tion indices. It is expected that some of the design
features of both of these candidate indices will become
incorporated into a Standard Air Pollution Index which
will be recommended by the task force. The task force
expects to report its recommendations in the spring of
1976.
Russell W. Peterson, Chairman
Council on Environmental Quality
iv
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ABSTRACT
This report presents the findings of a detailed survey
of air pollution indices that are presently utilized or
available. The survey included a review of the existing
literature on air pollution indices, telephone discussions
with personnel from the 55 largest air pollution control
agencies in the United States and Canada, and a case study
of a three—State region in which an attempt is being made
to develop a uniform air pollution index. These three data
sources have enabled the preparation of the most extensive
compendium of air pollution index material currently in
existence.
Two general types of air pollution indices have been
developed: (1) short—term and (2) long—term. This study
provides the first systematic analysis of the short—term
indices that are used routinely by local agencies and news
media across the Nation to provide the public with simple
guides for assessing the severity of local air pollution.
Of the 55 metropolitan air pollution control agencies
surveyed in the United States, 33 routinely used some form
of short—term air quality index. However, it was found
that nearly all of the indices had different mathematical
formulations and different meanings to the public. For
example, an index value of 100 reported in Washington, D.C.,
meant something entirely different from a value of 100
reported in Cleveland, Ohio. The long-term indices, which
indicate trends in environmental quality, are intended
primarily for use in formulating and evaluating local or
national environmental policies. As a result, virtually
none of the long—term indices are being used by metropolitan
air pollution control agencies.
diversity of air pollution indices creates potential
confusion, raises questions about their technical validity,
and prevents the indices from being used to give a national
picture of air pollution problems. From the case study and
agency comments, it was possible to identify general criteria
which would need to be met by a standardized index. These
criteria were then used to formulate two examples of
possible standardized air quality iridic . To evaluate the
feasibility of establishing a standardize index, it is
recommended that a Federal Interagency Task Force on Air
Pollution Indicators be established.
V
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Th j OF C TENTS
Page
FOREWORD.............. ............ ........ iii
v
LIST OF TABLES . . . . . • • • . . . . e . e . . • • • . • • • • e • . IX
LIST OF FIGURES.........S. ............ .. .. X i
CHAPTER
I • EXECUTIVE SUM1 I1 RY. • . • • . . . • • . . . . . . . . . . • . . . . 1
1. Purpose ofStudy.................... 1
2 . Methodology. . . . . • . . . . . . . . . . . . • . • . . . . 2
3. Findings. • . • . • . • . . . • • . . . • . . . . • . . ••.. 3
4 . Recorrunendat ion. • . . . . . . . . . . . • . • . . . . . . 6
II • SUM1 IPt.RY OF FINDINGS • . . . . . • . . , . . . . • . . . • . , . • 8
III. INTRODUCTION.. . • . . . . . . • . • . . • • • • . . . • . . . . . . . 15
1. Definitionoflndex....,............ 16
2. Air Quality Standards and
Episode Criteria.................. 19
IV. LITERATURE REVIEW. • • . . . . . . . • • . • • • . • • • • • . . . 23
V. SURVEY DESIGN. . • • . • . . . . . . . . . . . . . • • • . . . . . • . 28
1. SurveyPopulation................... 28
2. SurveyApproach..................... 33
3. Case Study... • . • • • • • • . . . . . • . . . . • • . . • 34
VI. SURVEY RESULTS. • • • •• . . . . . • • . . . • • . . . . • . • . • • 36
1. AgenciesUsinglndices.............. 36
vii
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TABLE OF CONTENTS (Cont’d)
Page
2. Index Classification System......... 40
3. Results of Classification.,.......... 53
4. Comments fromRespondents........... 65
5. Display and Dissemination
Techniques.. . . . . . . . . . . . . . . . . . . . . . . 71
VII. A CASE STUDY OF THE DEVELOPMENT OF
A COMMON AIR QUALITY INDEX FOR A
TRI—S TATE R EA. . 74
VIII . CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
IX. FUTURERESEARCHNEEDS..S........, .P,...S .. 88
1. ScientificBasis..,...,, .. .,,,.. ..,. 88
2. PublicAttitudes...,..... . .,..., . . ., 89
3. IndexReportingSystems...,......... 92
4. MonitoringSiting................... 93
5 . Follow—up Study. . . . . . . . . . . . . . . . . . . . . 94
REFERENCES..... ..•....... . . . . . . . . . . . . . . . . • 96
APPENDICES
A. AIR POLLUTION INDEX DATA SHEET...... 99
13. INDEXANALYSISRECORDS...e.e........ 101
C. COMMENTSFROMRESPONDENTS........... 132
D. EXAIVIPLES OF INDEX DISPLAY AND
DISSEMINATION TECHNIQUES... e .. *..... 145
E. STANDARDIZED URBAN AIR QUALITY
INDEX..........,...,..,.,.,......... 150
F. PRIMARYSTANDARDSINDEX......,., . .,. 161
vijI
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LIST OF TABLES
P a e
How 13 Cities Report an Index Value of 25...... 5
1. Differences in the Design Characteristics
of Various Indices......,.. • ............... . • 12
2. National Ambient Air Quality Standards and
Recommended Federal Episode Criteria........... 20
3. Air Pollution Indices Reported in the
Literature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4. U.S. City/County Air Pollution Control
Agencies with Staffs Greater Than 1O.........,. 30
5. State—wide Air Pollution Index Systems........ 31
6. Province—wide Air Pollution Index Systems...... 32
7. Variables Used in U.S. City/County Air
Pollution Indices.. . . . , . . . . . . . . . • • • • .. . . . . . 39
8. Variables Used in State—wide and Province—wide
AirPollution lndjces..........,. ... 41
9. Classification of Indices Reported in the
Literature... . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 54
10. The 15 Index Types and Their Users.........,... 55
11. Summary of Index Classification Results........ 57
12. Number of Variables Included in Index
Calculation.. •......... . ...... 56
13. IndexcalculatjonMethods....,..,............., 58
ix
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LIST OF TABLES (Cont’d)
Page
14. lvlodeoflndexCalcuiation 59
15. Basis for Index Descriptor Categories......,.. 60
16. The Frequency Distribution of the 41 Words
UsedforDescriptorcategories.,,.......,,,.,.. 63
17. Indices Using the More Commonly Occurring
WordsinDescriptorcategorjes...........,...., 64
E—i Breakpoints forSUAQI.,,.,........ 153
E—2 SUAQIDescriptorcategories.. .....,, . .,,, •, • 154
F—i Possible Adverse Health Effects for PSI
Greater Than 100. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
F—2 PSlDescriptorcategories.............. . . 164
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LIST OF FIGURES
Page
1 . Index calculation . . . . . . . . . . • . . e • • • 16
2. Size distribution of U.S. city/county air
pollutioncontrolagencies..................... 38
3. Nomograph for determining the Oak Ridge Air
Quality Index (ORAQI ) . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4. OBAQI function for sulfur dioxide and
part ± cu 1 ate mat te r . . . . . . . . . . . . . . . . . . . • • , • , • • • • • 46
5. Example of a segmented linear function
for carbon monoxide . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
6. Indexclassificationsystem.................... 52
7. Histogram of the number of descriptor
categories used in U.S, city and county
airpollutionindices...............,..,......, 61
E—l SUAQI function for carbon monoxide... ....,..... 155
E—2 SUAQI function for sulfur dioxide.............. 156
E—3 SUAQI function for particulate matter.......... 157
E-4 SUAQI function for the product of sulfur
dioxide and particulate . . ..... . . . . . ....... 158
E—5 SUAQI function for nitrogen dioxide............ 159
E—6 SUAQI function for photochemical oxidants...... 160
xi
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CHAPTER I
EXECUTIVE SUMMARY
1. Purpose of Study
Public awareness of air pollution problems has increased
the need for timely information about changes in air p Oi—
lution levels. Every day, air quality conditions in our
Nation’s cities are presently being reported to millions
of Americans by local agencies and news media. In more
than half of our large cities, the public receives this
information —— on television, on the radio, and in print ——
through the use of various air pollution indices. A typical
air pollution index is an interpretive technique which
transforms complex data on measured atmospheric pollutant
concentrations into a single number or set of numbers in
order to make the data more understandable.
Although many technical papers proposing specific
indices appear in the literature, no detailed study has been
available to describe the characteristics of the many indices
that are actually being used for public reporting. How many
air pollution indices are there in the United States? What
are the experiences of metropolitan agencies with these
indices? Have the indices proposed in the literature been
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adopted by State and local air pollution control agencies?
What pollutants do the indices include? How are the indices
calculated and how are the individual pollutants weighted?
What reporting formats are used to convey this information
to the public?
This study is the first comprehensive effort of its
kind designed to answer these questions by asserthling a
national inventory of the air pollution indices currently
in existence. It draws upon this inventory to compare
different indices, to make inferences about current practices
regarding these indices, and to identify relevant problems
that should be brought to the attention of public officials.
2. Methodology
This study employed three main approaches to gather
information: (1) a review of the existing literature on
air pollution indices; (2) a survey soliciting information
from air pollution control agencies in U.S. cities,
States, and Canadian Provinces; and (3) a case study of a
three—State area in which an attempt is being made to
adopt a uniform air quality index. The information for the
survey was solicited by telephoning the 55 largest
metropolitan (city and county) air pollution control
2
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agencies in the United States, as well as a nurr er of
State and Province agencies that make use of indices.
The case study of the Steubenville —Wheeling—PittSbUrgh
(three—State) area provided information about the problems
encountered when three neighboring jurisdictions, each of
which presently uses a different index, attempt to adopt a
common format.
An extensive library of documentation of air pollution
indices was developed during this study. This report
presents a systematic analysis of the data contained in
this documentation.
3. Findings
This study has revealed a great diversity and lack of
co isistency i. . the vv’ay air cjuality cor ditio .s are reported to
the public by means of air pollution indices. States,
Provinces, and u.s. cities use daily informational indices
which di±fer from each other and which greatly differ from
the more complex, long—term trend indices that appear in
the scientific literature. State and local air pollution
control agencies clearly prefer the simpler types of indices.
Nevertheless, the variation in these simpler indices is
striking. Among the 33 United States cities and five States
3
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currently utilizing daily air pollution indices, there are
15 basically different index types. With two minor exceptions
(when the descriptor categories* are taken into account), no
two indices are the same . This diversity suggests that
consistent scientific rationales have been lacking in the
development of air quality indices.
Because of this variability, the individual who travels
to different cities may easily become confused about air
pollution levels in each city. The table on the following
page illustrates this problem. In 13 cities, a reported
index value of 25 (or 25 ppm for carbon monoxide) would be
accompanied by any of 10 different descriptor words. If a
citizen does not differentiate between index types, he
would encounter descriptor words in different cities
ranging from “unhealthy” to “fair” to “excellent,” all
describing the same index value of 25. Striking dif-
ferences also are found in the way different cities calculate
their indices, the number of pollutants they include, and
the manner in which they report their indices to the public.
To quantitatively summarize these differences, the authors
of this study developed an index classification system.
*A “descriptor category” is the interpretive word
issued along with the index value (for example, “good”,
“unhealthy”, “clean air”).
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HOW 13 CITIES REPORT AN INDEX VALUE OF 25 ”
City
Calculation
Method /
Air Pollution
Descriptor
Tampa, FL
A
Moderate
Denver, CO
B
Fair
Washington, DC
B
Fair
Baltimore, MD
B
Fair
Cincinnati, OH
B
Excellent
Miami, FL
C
Normal
Louisville, KY
C
Good
Los Angeles, CA
D
Stage 1
San Francisco, CA
D
Severe
St. Paul, MN
D
Unhealthy
Trenton, NJ
D
Unsatisfactory
Albany, NY
D
High
New York, NY
D
Unhealthy
‘For methods A, B, and C the index value of 125 is
calculated from one or more pollutant concentrations;
for method D, individual pollutant concentrations are
reported and an index value of 25 corresponds to 25 ppm
carbon monoxide.
The calculation method is the most important component of
the index type; see Chapter VI for further explanation.
5
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The present diversity of air pollution indices creates
potential confusion, raises questions of technical validity,
and. prevents the indices from being used by anyone to obtain
a national indication of air pollution problems. From the
comments received from air pollution control agency personnel,
it is evident that a standard air pollution index, or
a standardized air quality reporting format, might be both
beneficial and welcome. However, as seen in the three-State
case study, a standardization effort is an extremely dif-.
ficult and complex undertaking. From the case study and
agency coments, it was possible to identify general criteria
which would need to be met by any standardized index. Based
on these criteria, two examples are given of possible
standardized indices (Appendices E and F). Such a stand-
ardization effort also should specify the ways in which a
local agency might select the data for the index, including
quality control practices, instrumentation, and site location
criteria.
4. Recommendation
To evaluate the feasibility of establishing a standardized
index and standardized index monitoring criteria, it is
recommended that a Federal Interagency Task Force on Air
6
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Quality Indicators be established. This report should serve
as the starting point for the deliberations of this task force.
The task force also should consider the development of an
Index Monitoring Guidelines document to assist local agencies
that wish to adopt such a standardized index system or
reporting format.
7
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CHAPTER II
SUMMARY OF FINDINGS
This study has revealed great diversity and lack of
consistency in the air pollution indices that are currently
used by air pollution control agencies in the United States
and Canada. Of the 55 largest U.S. metropolitan air poi-.
lution control agencies surveyed in this study (those with
more than 10 staff members), 33 use an air pollution index.
Five States and two Canadian Provinces operate State—wide
(or Province—wide) index systems. Most of these indices
have been initiated since 1970.
No strong relationship emerges between the size of an
agency and its tendency to use or not use an air pollution
index. Small agencies (fewer than 20 staff members) appear
less likely to use indices, perhaps because they lack the
monitoring data or the staff to routinely compute an index.
By developing an “index classification system,” it was
possible to analyze and compare the various indices reported
in the literature and those that are used by the agencies
surveyed. For each index, this system evaluated:
• Number of variables
• Calculation method and mode
8
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• Descriptor categories
The majority of the indices appearing in the literature
incorporate five of the six National Ambient Air Quality
Standards (NAAQS) pollutants (excluding hydrocarbons), use
a nonlinear calculation method, and combine variables into
one number (combined mode) rather than reporting them
separately. The descriptor categories for these indices
are either arbitrary or based on the NAAQS.
The index classification system identified 15 basic
kinds of indices in the city, State, and Provincial agencies.
Among the 33 U.s. cities with indices, 40 percent use indices
of five variables. The remaining agencies are approximately
equally divided among those using one, two, or three variables.
Nearly all of the cities (91 percent) incorporate particulate
matter (total suspended particulates or coefficient of haze,
with the latter twice as common). The next most commonly
used index pollutants are carbon monoxide (73 percent of the
agencies), sulfur dioxide (73 percent), oxidant (52 percent),
and nitrogen dioxide (48 percent). One index includes
visibility and another incorporates particle scattering alone.
A majority of U.S. city agencies (58 percent) favor
a linear calculation method. Approximately one-third
9
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report actual concentration values. Only four agencies
(13 percent) use a nonlinear method. Forty percent of the
agencies base their index on the maximum of one of the
variables it contains, while 33 percent report all variables
individually . Only 27 percent aggregate the variables
together into a combined index. Although most agencies
prefer either three or four descriptor categories, a total
of 41 different descriptor words are identified. The
majority of the U.S. agencies (67 percent) base their
descriptor categories either on the NAAQS or on the
recommended Federal Episode Criteria; the remainder use
arbitrary categories.
The State—wide and regional index systems (Minnesota,
New Jersey, New York, Ohio, and the District of Columbia
metropolitan area) incorporate three, four, or five
variables into their index. Two of these systems report
actual concentrations; two use a linear function; and one
reports actual concentrations along with a nonlinear index.
As in the cities, three or four descriptor categories are
preferred, although one State system uses 12 categories.
All State systems base their categories on the NAAQS or
the Federal Episode Criteria.
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Table 1 summarizes the findings of this report by
comparing the characteristics of the indices appearing in
the literature with those used by U.S. cities, States,
and Canadian Provinces. Very striking differences emerge,
particularly when indices in the literature are compared
with those in current use by air pollution control agencies.
Most published indices are relatively complex: they employ
a nonlinear calculation method and are combined in form.
Although the two Canadian Provinces use this type of index,
the U.S. State and city indices prefer the simpler linear
calculation methods and seldom combine variables. Thus,
the air pollution indices which have been formally proposed
or discussed in the literature are not widely used by U.S.
air pollution control agencies.
Some insight into why this may be so is provided by
the comments from air pollution agency personnel (Chapter VI).
One reason for an agency choosing a simple index, or, in
some cases, choosing no index at all, is the need for the
index values to be consistent with the public’s perception of
air pollution levels (reduced visibility, eye irritation,
etc.). Many of the published indices do not address this
problem.
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TABLE 1
DIFFERENCES IN THE DESIGN CHARACTERISTICS OF VARIOUS INDICES
“Inc1udes both linear with
(see Table 13).
“Includes individual and maximum modes (see Chapter VI).
£/Does not include adjustments for agencies which use two calculation methods
(see Tables 13 and 14).
‘Pindex includes seven variables.
I-
t )
Number of Pollutant
Variables Included
size)
‘ o
I I
.
Appearing in
(8) 37% 63%—’
Use (40) ’ 52% 48%
Calculation Method and Mode
Descriptor
Basis
(11
C
0
•.-
‘U
4
O) ‘ U I 4J
C
—I (U ( Ua)
()
iJ
0 00
Z . C)
63% 37% —
18% 52% 30%
.o
Q)
rtl C
r
C
•rl
0
0
0 C
U
88% 12%
30% 70%
‘U
.-1
1.1
‘DO)
C 4 )
COO
I-
‘U
4
‘DO 4 )
CC0 -d
flj.rl
-I
U)1 I
50% 50%
70% 30%
(33) 54% 46%
(5) /’ 40% 60%
Provinces (2) 50% 50%
12% 58% 30%
20% 40% 40%
100% — -
27% 73%
20% 80%
100% —
67% 33%
100% —
50% 50%
nonconstant coefficients and linear with constant coefficients
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As part of this investigation, a case study also was
conducted in a three—State region attempting to adopt a
common air pollution index. Although many problems arise
from such a multijurisdictional effort, there was general
agreement —— also observed in the comments from some U.S.
Federal agencies —— that confusion could be reduced if the
Federal Government were to develop, endorse, and support
a single, uniform air pollution index. From the study
results, it is evident that the following criteria would
be desirable in any standardized index:
• Easily understood by the public
• Not inconsistent with perceived air
pollution levels
• Spatially meaningful
• Includes major pollutants (and able
to include future pollutants)
• Calculated in a simple manner using
reasonable assumptions
• Rests on a reasonable scientific basis
• Relates to ambient air quality standards
and goals
• Relates to episode criteria
• Exhibits day-to-day variation
• Can be forecast a day in advance
13
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As part of this study, two examples of possible
standardized indices have been developed and are offered
for consideration (Appendices E and F).
14
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CH7 PTER III
INTRODUCTION
In this era of “social indicators,” combining the
many parameters that provide measures of air pollution
into one number is an appealing prospect. Certainly, one
number that could accurately indicate the “severity” of
air pollution in a given city or across the Nation would be
of use both to the general public and to those involved in
implementation of air pollution control policies. While
this goal appears worthwhile, achieving it is not simple.
The complexity of the air pollution problem makes it
difficult to develop an index that is really meaningful.
To see how different air pollution control agencies
have approached this problem, the 55 largest metropolitan
air pollution control agencies in the United States were
surveyed in-depth. Canadian Provincial agencies and State
air pollution control agencies in the United States known to
use air pollution indices were also surveyed. In addition,
the literature was reviewed at length to determine the
characteristics of published air pollution indices and the
experiences with these indices of persons engaged in research
15
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or administration. Finally, a case study was undertaken of
three neighboring United States cities which were attempting
to develop a comon air pollution index.
1. Definition of Index
An ‘air pollution index’ is defined in this study as
a scheme that transforms the (weighted) values of individual
air pollution—related parameters (for example, carbon
monoxide concentration or visibility) into a single number,
*
or set of numbers (Figure 1). The result is
parameter X 1 a
parameter X
2 Transformation • Index
parameter X 3 i g(X 1 , X 2 , X 3 , ... X )
parameter X
Figure 1. Index calculation
a set of rules (for example, an equation) that translates
parameter values —— by means of a numerical manipulation ——
into a more parsimonious form. (In set theory , this process
*Sorne other recent publicat 9ns, such as those of the
Council on,Environmental Quality — 1 and the National Academy of
Sciences,. I have defined indices more broadly to include, for
example, air, water, and recreation. Such a broad definition
was not suitable for the scope of this investigation.
16
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is viewed as mapping of elements contained in one sample
space into another sample space.)
The following evaluations were made to determine
whether an agency used an “index.” If an agency reported
just the actual air pollutant concentration values to the
public -— micrograms per cubic meter or parts per million
(ppm) -— or concentration values along with the Federal
standards, this was not considered an “index.’ Rather,
an index must be based on some set of rules which translate
the values into a new variable, or which make interpretations
of these values. At the very least, an index is any system
in which specific concentrations ranges are grouped into
air quality “descriptor categories.” For example, a system
which designates 0—3 ppm carbon monoxide as “good,” 3—15 ppm
as “satisfactory,” and 15—40 ppm as “unsatisfactory” was
considered to be an index. In its most elaborate form, an
index is an equation which combines many pollutants in some
mathematical expression to arrive at a single number for
air quality.
Air quality indices can be grouped into two categories:
• Long-term indices
• Short—term indices
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The long—term indices are intended to evaluate changes in
air quality over periods of several years or more. A
typical example of such an index is the Mitre Air Quality
Index1 ’ which was applied to air quality data for a
number of cities across the country. Ideally, these indices
are for the purpose of assessing the effectiveness of
enforcement polices in improving air quality; however, few
are being used in practice. Long—term indices appear often
in the literature, as discussed in Chapter IV.
The short—term indices are used widely by State and
local air pollution control agencies and are the focal
point of this investigation. These indices, which seldom
have been described in the literature, usually are intended
to inform the public about daily changes in air pollution levels.
Although episode warning systems are not reported daily, they
do consist of descriptor categories which are reported when-
ever concentrations exceed specified levels. In some cities,
this happens frequently, and the distinction between an
episode warning system and a daily informational index
becomes blurred. Thus, air pollution agencies with episode
warning systems are classified as having indices.
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2. Air Quality Standards and Episode Criteria
Many air pollution indices are based on existing
Federal air quality standards, on recommended Federal pisode
Criteria, or on both. The Clean Air Act authorizes the
Federal Government to establish National Ambient Air Quality
Standards (NAAQS) for those air pollutants which are poten-
tially harmful to the public health and welfare. In April
1971, NAAQS were established for six air pollutants: sulfur
dioxide (so 2 ); particulate matter (total suspended particulate,
TSP); carbon monoxide (CO); photochemical oxidant (principally
ozone, 03); nitrogen dioxide (NO 2 ); and nonmethane hydro—
carbons. ’ The standard for nonmethane hydrocarbons was
established not because hydrocarbons affect health and welfare
but because they are a precursor to oxidant in the atmosphere;
they are therefore controlled to achieve the oxidant standard.
The NAAQS (Table 2) are not to be exceeded more than once a
year. Primary standards are intended to protect against
adverse effects on human health, while secondary standards
are intended to protect against effects on welfare (effects
on vegetation, materials, visibility, etc.). For some
pollutants, both one vear and shorter—term values (1, 3, 8,
or 24 hours) are specified.
19
-------
TABLE 2
NATIONAL AMBIENT AIR QUALITY STANDARDS
A ND
RECOMMENDED FEDERAL EPISODE CRITERIA
Pollutant, Units/
Averaging Time
Secondary
Primary
,
Alert—’
,
Warning ’
Emerc3ency
Signifiqant
Harm /
Sulfur dioxide
og/m 3 (ppm)
1 year
24 hours
3 hours
1
,300(0.5)
80(0.03)
365(0.14)
800(0.3)
1,600(0.6)
2,100(0.8)
2,620(1.0)
Particulate matter
pg/rn 3 (COH)
1 year
24 hours
60
150
75
260
375(3.0)
625(5.0)
875(7.0)
1,000(8.0)
Product of
Sulfur dioxide and
Particulate matter
(ppm x COn)
4
6.5 x 10
(0.2)
5
2.61 x 10
(0.8)
5
3.93 X 10
(1.2)
4.90 X 10
(1.5)
Carbon monoxide
n /m 3 (ppm)
8 hours
1 hour
10(9)
40(35)
10(9)
40(35)
17(15)
34(30)
46(40)
57.5(50)
144 (125)
Oxidant
ug/m 3 (ppm)
1 hour
160(0.08)
160(0.08)
200(0.1)
800(0.4)
1,200(0.6)
1,400(0.7)
Nitro9en dioxide
pg/ma (ppm)
1 year
24 hours
lhour
100(0.05)
100(0.05)
282(0.15)
1,130(0.6}
565(0.3)
2,260(1.2)
750(0.4)
3,000(1.6)
938(0.5)
3,750(2.0)
Hydrocarbons
0gm 3 (ppm)
3 hours
(6 to 9 a.m.)
160(0.24)
160(0.24)
“The Federal Episode Criteria specify that meteorological Conditions are such that pollutant
concentrations can be expected to remain at these levels for twelve (12) or more hours or
increase; or, in the case of oxidants, the situation is likely to reoccur within the next
24 hours unless control actions are taken.
‘Prior2ty 1 regions must have a contingency plan which shall, as a minimum, provide for
taking any emission control actions necessary to prevent ambient pollutant concentration
at any location from reaching these levels.
20
-------
The States are required to develop emergency episode
plans for regions designated by the Federal Government as
“Priority I Regions.” The Federal Government has published
“example regulations”- 2 ” which are intended as guidelines to
assist the States in developing episode plans. These example
regulations include recommended “Episode Criteria” specifying
concentration values which “justify the proclamation of an
air pollution alert, air pollution warning, or air pollution
emergency.” The criteria include values for all pollutants
covered by the NAAQS except hydrocarbons (Table 2). Using
the Federal Episode Criteria, an air pollution control agency
would declare an “Alert”, the first stage of the episode
warning system, whenever the specified concentration for
any one of the five air pollutants is reached or exceeded
at any air monitoring site. The Federal Episode Criteria
also include specified values for the product of sulfur
dioxide and particulate matter.
Two different measurement techniques are commonly used
for particulate matter —_ the high-volume sampler and the
tape sampler. The high—volume sampler gives the 24—hour
average of TSP in micrograms per cubic meter, while the
21
-------
tape sampler gives coefficient—of—haze (COH) units for
averaging periods as short as 2 hours. There is considerable
evidence that the two measurement techniques do not provide
compatible results, and the Federal Government has specified
the high—volume sampler as the “standard reference method”
for use by the States in determining compliance with the
particulate NAAQS. In this report, TSP denotes particulate
matter as measured by the high-volume sampler, while COH
refers to the tape sampler measurement.
22
-------
CHAPTER IV
LIThRATURE REVIEW
The literature on air pollution inäices8 8,’ has
focused on the development of long—term trend indices.
Little has been published on the short—term indices
commonly used by State and local air pollution agencies.
Although the long-term indices have appeared in the
literature, discussions with governmental personnel have
revealed few cases in which such indices have actually
been used to develop or evaluate major air pollution
policies.
Each of the eight air pollution indices reported in
the literature (Table 3) differs in terms of the number of
applicable pollutants, method of index calculation, and
descriptor categories. As a result, the overall meaning of
each index is different. One of the first short—term air
quality indices to be published was Green’s Index.W This
index, which combines subindices for sulfur dioxide and
smoke shade (COH), is based on proposed and adopted air
quality standards and on projected concentration/health
effects relationships. The coefficients and exponents for
23
-------
Grunt Cornbii.d
lrrdtn CI I
Online Air Pollution
od in IAPI I
CI 0.51 840 00943
* 266 Con 0 - 0 l
API 02305 COIl
12t0 soj’
P 1 140 00 =
TSP SO NO 1 CO
375 4430 514
tIC 09
19300 244
wrr.rn 5530 PMSQr
to ntrçi.r In I tr
ORAQI-
[ s. ; IC,l5 4 1]’ 3P
Cr 00 10. 04 pnIInr.rrr
5, nltodird for pollutan T ’
MAOI
l-rndrc.ror or tins
poll..
5.6 CP O Pool Borroad
Vnnr,Ionirr Voronos
0-49 Dinir.d 1.0.1, 0101,
50-59 P,,tr alt o,
mtd i.r.
60.99 Sorond al,tr
en’ Thod 41011
ICC , Porrnrn, Iloal
0-34 A1 0 . 0 1.01.
37-49 Ailoirory 104.1
50-74 Pin Ally
75-99 Oaco,rd A1.rr
100’ bpitnd. lIrrol lrold
• 20 0 nc.lloor
70 39 Good
40-59 Pair
60.19 Poor
80-99 Bid
rot ’ 5 00goroo,
MACI - r no o ld. dod
MA CI ,i 3 ttd,rn.r or
..cnd.d
MACI ‘3 on. Or 01000510
o .c..d.d
B OO ‘ golf nra. bdong Intl
600 - I:ir lion 000114
t.nindd
root is I.ttd on Or000tad and 0009404 air
uuai.rytranro.rdt. SO, 000blorrlliorrt Or Cans
c l I lgor n drlI•r by. ronror 0150 , COP colon
drrlor by o tr Io, 0 r 003 lr.dta it ann lin.ui.
only during coldir 1.11cr, toll.. SO. norm..
IlIr Inn i ore .l.o.rS
Tb. no .41 i100r,00,r,oporomnr r.I.r. API elicit
0 pnllur,00 Ioaltarr.,narl during pill or
poliorron Ipi000et
Anroal poIIor.nr ron000rr.r 001011 rfrnid ld by
Oar roIp rri,o rein -ion. roo m, loon h 00 i
or lurualont Irond.rdl which it bawd on rho
Colrlornra or dry .’ appicprriT olrondordt Tb.
00 coin. irniud., roil eo,nrorad irv In 50 ,
PC 0 hr ‘00. Th t 0011 arm it rho ,trriil,tr
of 0. PM or bOr rem,
ml .. may I . *dInnlirod icr .rc *ombrnarinn
o l roar r r rob poilolaol, cling rurrrocr.ph,
lroiioIiollraod.rdt, 0,, on 24 hr arrapoli-
root or .anondary NAAOS WIlan poilur.rr
0000.nrr.riont ar or liocigrou r d lanai..
Q OAQi - 0 rrrr.rr cli
slaodarrft. ORAOI ITO
100.1 ‘mac no n.iuoi,rad or any nnmb,yarror
c l i. I rnSpoIInri .rrrtir,dir .rnriie ha.ad
on ..nondary NAAO0
— 11100 uorrn.nrr.r ion or nol luiarr I,
dur,mogloog.nrnr.astcr.rroor porodo,
artpaoi lr.dbyer ,ndtrd0 ,, ,
Cr c rrra.n rnrar.n,r.r roe or pol lrild er I,
durorrg Sourly rrrod,ur.rrwor pnriodlr,
a, tp.niirad mo ,r,rrdard 0 rli
I ,r Cilr - ilr
r - 0 ,r Cur 0 ih
led.. reds be roiouiorarl or inn nnnnbin.roe
c li 1 rod poiloraror.. Bit bi..d on beta
sanorrdlrp SAAOS nor nba e.bnd.d nor.
l I ly ono. per 0 00r, Ii,, rh 00 0rrofld,arrd,,
gtoon by
‘no.
A 141 il lC 1 j l
• umonil ion of rho.. c .b .s. C,y. 04111.1
.nn.ad rho Snuriy mt.oiraer.nr porrod
or roollor.nr ia . t,norlrod by .rarrd-
ard 0 10
r 1 1 if fC j,l 1 - 5 ilr
‘Oi l IC 1 5 ‘‘ rli
Tb. cal burn.d ltoo.I it thr.i,raf by non.
bream roof d.liwrru, o.rrmilarrrrp nolorero
onion,. of iru ‘cr0 onrunh rn 0.1 oombu,-
ron eroduor’ I ,. mto.db r,bhg prodoot of ha
onn.nrnm’i ira. eritiog doers end ornd wa.d
TOO 904 leer 0 nilgnr.b.n for toy corrrnrnaronn
of fronr t - 1105 pnl ioranm. nohon oono.r.r.e-
Soot Ira pn.drnr.d by a .orrpla d,Ilu,,.e regd.l
00100 bOll reline 0,101015 data. tI,i pradinrad
torrntrrlr.r ions or. loon .rand.rdr lod to slot ri le
.randard,aad pollurtol in st If 1
—
P1 ‘Yo ’
#0.1.
Table 3
AIR POLLUTION INDICES REPORTED IN THE LITERATURE
P daoea
0.rdbl.n
€ Ouorron
Pare nt
C.r orot
On.orrpriorr
Air.., 1 c .
NA
9’ 1900
0-590°
6 ’ r oar
0- 0000
0- St
0. -
SO, COd
9O , COP
P 5 90 60 CO. 0 r’ ‘ -
NO . OX. PC
Oan A1. Au Or,airly CO 60 r’ TSP,
lOdtt 1096011 50,00
Morr. Air Orairty lnd.t CO. SO., TOP.
1 1 .60 1 1 501.00
Onir.r,r. Vu.., br.. CO, SO,, TSP,
(bIl l 00
Cwnboniorr Prodoort
roast OCPII
Air Qoofirs led.. CO. SO -
06001 NO,.On
ovo .
6 1 ’rr.drn..ot for loch
o c r r,00nl
NA NA .
NA NA
No NA.
AOl C W 1 P 1 1
61’ en.rgfrrtrer.nrorror
P.llo,orr. apo.rirn
Pr 4 I0 1000 00loid poilorant
nd ...
V - pe nal n un
0-000.0 dandard daortludo
0 = prolrtnrod poliur in f norro.nrrir Ion
= et... predot.d poll,ranrnorro.nrr.
I , - trmndiod d.oearron ol rtrtofrnrtd porlo-
raolnono.ulrrnr000r.
24
-------
the sulfur dioxide arid COM index equations were chosen so
that the resulting values fit pre—selected categories. The
combined index value then is obtained by averaging the two
sabiridjces. [ Ontario9 0 ’ uses a similar index (Appendix B),
with the coefficients and exponents changed slightly to fit
air quality standards in effect in Canada.] Green’s index,
exhibits what may be termed an “eclipsing” phenomenon.
Eclipsing occurs because one of the several pollutant
concentrations in the index can exceed its air quality
standard, but the combined index value can simultaneously
be less than a value equivalent to the standard. Eclipsing
is characteristic of many combined indices.
The Pindex equation- ” combines the weighted concentra-
tions of the six NAAQS pollutants with terms representing
solar radiation and the particulate—sulfur oxides synergism.
*
The weighting factors are based on the 1—hour equivalent
of the California standards proposed when the index was
developed. The Pindex equation may be applied to long-term
ambient air quality data or to emission data from specific
*The 1—hour equivalent concentrations are obtained by
a correlation analysis relating the 1—hour and 24—hour
average concentrations.
25
-------
source categories such as transportation, industry, power
plants, space heating, and refuse combustion. As a combined
pollutant index, Pindex exhibits an eclipsing effect.
The Oak Ridge Air Quality Index is based on the 1-hour
equivalent concentrations of the secondary NAAQS. It is
calculated for any combination of from one to five of the
pollutants using a specially designed nomograph. The co-
efficient and exponent of this index have been selected to
give index values of 10 at background pollution levels and
100 when pollutant concentrations exceed the standards.
Although the range is divided into several well-defined
categories, no correlation with health effects is implied
by its developers.
The Mitre Air Quality Index ’ (NAQI) is based on the
secondary NAAQS and is intended to depict quarterly changes
in air quality, using data for the most recent 12—month
period. The index is calculated as the square root of the
sum of squares of five of the six NAAQS pollutants (excluding
hydrocarbons). Each component, in turn, is the square root
of the sum of squares of the normalized pollutant concentra-
tions. These normalized pollutant concentrations are obtained
by dividing the mean pollutant concentration by the standard
applicable to the averaging time.
26
-------
Although this method of calculation guarantees an
index value of at least 1.0 if any pollutant included in
the computation exceeds its standard value, it introduces
a gray area between 1.0 and 3.0 where each pollutant
concentration may or may not exceed its standard. When
index values occur in this range, each indicator is in-
spected to determine if a standard has been exceeded.
Values greater than 3.0 imply that at least one standard
has been exceeded. The purpose of the ö coefficient in the
indicator equation is to eliminate from the index calculation
pollutant concentrations below their respective standards.
This feature prevents eclipsing.
The Extreme Value Index ” (EVI) is calculated in a
fashion similar to the MAQI except that the EVI indicators
sum only those squares of the pollutant/standard ratios
which are greater than or equal to 1.0. Such a calculation
scheme (which avoids the eclipsing phenomenon) measures the
extent of very high—level pollution for short periods of
time and therefore can be used to describe episodes. The
resulting index range is discontinuous between 0.0 and 1.0,
with values greater than 1.0 indicating that standards are
being exceeded.
27
-------
CHAPTER V
SURVEY DESIGN
The existing air pollution literature can provide
little information about the routine use of indices by
air pollution control agencies. To learn which air pol-
lution indices are in common use and to gain insight into
the experiences of air pollution control agencies with
these indices, an in—depth survey of these agencies was
required. In this survey, agencies throughout the United
States and Canada were telephoned and asked to send infor-
mation describing their index. The data base in this
investigation was asseriibled from notes taken during the
telephone conversations, from written materials received
from the agencies, and from a case study involving three
neighboring air pollution agencies in Ohio, Pennsylvania,
and West Virginia (Chapter VII).
1. Survey Population
The population surveyed in this investigation
consisted of the 55 largest metropolitan (city and county)
air pollution control agencies in the United States, along
with State air pollution agencies in the United States
known to operate State—wide air pollution index systems.
28
-------
It also included the Canadian Provinces with air pollution
control agency staffs of 10 or more persons and one Canadian
city which uses an index. To select the survey population,
the total number of staff members from every city and county
air pollution agency was computed using the Directory
Governmental Air Pollution Agencies , published by the Air
Pollution Control Association).2/ Only those U.S. air
pollution agencies having 10 or more staff members were
included in this survey population (Table 4). In the
United States, the resulting survey population consisted
of 55 agencies. Telephone inquiries revealed that, in 14
of these cities, the index was operated as part of a general
State—wide or regional index system. Six States were
operating this type of system: Connecticut, District of
Columbia, New York, New Jersey, Minnesota, and Ohio. These
State indices serve 59 cities (Table 5), but many of these
air pollution agencies have staffs smaller than 10 persons.
Also, the agencies in Baltimore, Maryland, Boston, Massachusetts,
and Portland, Oregon, are operated by the State but are not
part of a State—wide system. In Portland, the State not only
reports the air pollution index but it operates the entire
29
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TABLE 4
Birmingham. AL
Phoenix, AZ
Anaheim, CA
Los Angeles, CA
Riverside, CA
San Bernardino, CA
San Diego, CA
San Francisco, CA
Denver, CO
‘New Haven, CN
‘Washington, DC
Bradenton, FL
Jacksonville, FL
Miami, FL
Sarasota, FL
Tampa, FL
Atlanta, GA
Chicago, IL
Gary, IN
Indianapolis, IN
Louisville, KY
Baltimore, MD
‘Montgomery Co., MD
•Boston, MA
Springfield, MA
Detroit, MI
St. Paul, MN
Kan s City, MO
St. Louis, MO
Albuquerque, NM
‘Albany, NY
Buffalo, NY
e•Mineola, NY
New York City, NY
‘Rochester, NY
Charlotte, NC
‘Akron, OH
‘Cincinnati, OH
Cleveland, OH
Dayton, OH
•Toledo, OH
Oklahoma City, OK
‘Portland, OR
Philadelphia, PA
Pittsburgh, PA
Chattanooga, TN
Memphis, TN
Na ville, TN
Dallas, TX
Et Paso, TX
Houston, TX
Pasadena, TX
“Fairfax Co., VA
Seattle, WA
Milwaukee, WI
17
25
24
380
26
53
53
220
54
11
14
11
15
50
21
16
14
175
18
15
39
90
10
87
12
77
13
15
35
15
237
44
37
382
12
14
13
65
80
45
25
15
20
94
82
22
11
17
21
10
76
45
12
39
25
Discontinued Index
Replaced Index
Replaced Index
U.S. CITY/COUNTY AIR
POLLUTION CONTROL AGENCIES WITH STAFFS
GREATER THAN 10
City/County
Agency
Size
Material
Received
Index
In Use
Comments
S
S
.
S
S
S
.
S
S
S
S
.
S
S
.
.
S
S
S
Replaced Index
Discontinued Index
Replaced Index
Replaced Index
Replaced Index
Discontinued Index
S
.
.
S
S
.
S
S
S
S
S
S
S
.
S
S
S
S
S
S
S
S
.
S
S
S
S
S
S
S
• = City index is operated by State but is not part of statewide index system.
City index is pert of statewide or regional index system.
30
-------
TABLE 5
STATE-WIDE AIR POLLUTION INDEX SYSTEMS
U,
I-J
Connecticut
(Discontinued
Index)
District of Columbia
g/wbere no agency iiie
*State Açency
Alexandria, Va.
Arlington Co., Va.
Fairfax Co., Va.
Prince Georges Co., Md.
Montgomery Co., Md .
Washington, D.C.
Duluth
Minneapolis
Rochester
St. Paul
Ancora
Asbury Park
Atlantic City
Bayonne
Burlington
Canden
Elizabeth
Freehold
Hackensack
Jersey City
Morristown
Newark
Paterson
Paulsboro
Penns Grove
<10
<10
105*
<10
<10
<10
12
C 10
10
14
<10
37*
<10
13
Perth Anboy
Phi llipsburg
Some rvi 1 le
Tons River
Trenton
Albany
Buffalo
Kincjston
Mamaroneck
Mineola.-E isenhower Park
New York City—Roosevelt I l.
Niagara Falls
Rensse lear
Rochester
Schenectady
Syracuse
Utica
Akron
Canton
Cincinnati
Cleveland
Coluntu 5
Dayton
Lorain
Mansfield
Pa inesvi 1 le
Portsmouth
Steubenville
Toledo
Youngstown
13
<10
65
80
228*
45
<10
<10
<10
-------
city air pollution control agency as well. In Baltimore,
on the other hand, the State reports the index, but the
local air pollution agency is organizationally separate
from the State agency.
In Canada, only Montreal operates a city air pOll tj
control agency. Therefore, all Provinces with staffs of 10
or greater were included in the survey population. Alberta
and Ontario operate Province-wide air quality indices.
Eight cities within these Provinces issue daily indices
(Table 6).
TABLE 6
PROVINCE-WIDE AIR POLLUTION INDEX SYSTEMS ”
Province
Applicable City
Agency Size
Alberta
Calgary
Edmonton
<10
26*
Ontario
Hamilton
Happy Valley
Sudbury
Toronto
Welland
Windsor
-
-
70*
-
-
‘Where no agency size is given, size is unknown.
Province agency
32
-------
2. Survey Approach
Telephone calls were made to the agencies in the survey
population from August to December 1975. For each agency,
a respondent was sought who was very familiar with the
agency’s air pollution index, if any. In small agencies,
this usually turned out to be the agency’s director; in
the larger agencies, a public information specialist or a
professional in the field of monitoring and data analysis
usually was the respondent. With the respondent on the
telephone, the investigator went through an informal
question—and—answer session covering many of the items listed
in the “Air Pollution Index Data Sheet” (Appendix A). The
diversity and variety of indices prevented the investigators
from using a standardized questionnaire form, so the data
sheets served only as guides. All respondents contacted
were extremely cooperative and enthusiastic about providing
information.
Each respondent was asked, ‘Can you provide any
literature or description of your index?” Of the 55 agencies
on the major list (Table 4), 28 promised that they would
send written materials, and the materials were received from
all of these. In some cases, the telephone discussion
33
-------
provided sufficient information about the index, and no
mailed material was necessary. Some agencies not using
indices provided material that discussed their reasons
for not adopting an index or their experience with a
previously discontinued index.
The findings reported in this study are based mainly
on the large quantity of information mailed in by the
respondents. This information typically covered the nature
of the index, its method of calculation, the history of its
development, and the way in which it is reported. From
this information, along with the notes taken during the
telephone calls, an “Index Analysis Record” was prepared
for each agency (Appendix B). Analysis of these sheets
yielded the quantitative summaries and conclusions in the
following chapters.
3. Case Study
In the telephone survey, it was learned that three
neighboring cities —— Steubenville, Ohio; Pittsburgh,
Pennsylvania; and Wheeling, West Virginia —— were considering
adoption of a common air quality index. Presently, each
jurisdiction uses a different index, and members of the
public are exposed to all three indices through the news
34
-------
media. This has resulted in confusion about the air
quality in each city and in the region as a whole.
Adoption of a single index in the tn-State region would
alleviate this confusion. Currently, these air pollution
agencies are considering how this might be accomplished,
Because of the relevance of this effort to the present
study, the region was visited several times, and the
problem was examined as a case study (Chapter VII).
35
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CHAPTER VI
SURVEY RESULTS
Initially, information from the mailed responses and
from notes taken during each telephone conversation was
condensed and compiled into tables. The tabular compilation
was found to be inadequate, however, due to the varied and
sometimes extensive information received from the agencies.
Consequently, the information was assembled into the three
appendices. An Index Analysis Record (Appendix B) was
developed to present detailed factual information about
each index in a uniform format. Informal comments from the
agencies were copied into an extended table (Appendix C).
Examples of the ways in which indices are reported by the
news media were also recorded (Appendix D).
1. Agencies Using Indices
During the course of the survey, a total of 30 index
systems were reviewed and analyzed (Appendix C). In the
United States, 25 index systems are currently operating arid
three have been discontinued. In Canada, two are currently
Operating.
Of the 55 United States metropolitan air pollution
control agencies with more than 10 staff members, 33 agencies
36
-------
(60 percent) currently use an “air pollution index,” as
defined in Chapter III. The size distribution of the 55
agencies is skewed to the right (Figure 2), with most
agencies (60 percent) having fewer than 30 staff members.
No clear relationship is apparent between the size of these
agencies and their use of indices. However, small agencies
(fewer than 20 staff members) are less likely to use indices,
either because they do not have sufficient air monitoring
data or because they do not have sufficient staff to
calculate the index routinely.
Index Variables . The variables included in U.S. city/
county air pollution indices are shown in Table 7. If the
soiling index (COH) and high—volume sampler measurements
of total suspended particulate (TSP) are lumped together as
measures of particulate matter, then particulate becomes
the most common air pollutant included by these agencies
in their indices. Of these 33 agencies, 30 (91 percent)
include either COH or TSP; COH is used by 21 agencies and
TSP by 10 (Jacksonville, Florida, uses both). The popularity
of these two measures may be due to the increasing use of
telemetered air monitoring networks which cannot readily
handle TSP data determined by the high volume sampler, and
37
-------
251-
0
In, I
200 250
Agency Size
Agencies Using Indices
Agencies Not Using Indices
300
I
350 400
20
15
10
5
.3
(A) ‘a..
o 0
E
2
1
0
10
I
50
100 150
Figure 2. Size distribution of U.S. city/county air pollution control agencies.
-------
TABLE 7
VARIABLES USED IN U.S. CITY/CC*JNTY AIR POLWTION II ICES
Agency
Size
Co
°2
2
OX
COH
TSP
VIS
PS
Total
Anah.im ,CA 24 • • 3
LosAngelesCA 380 I I S 3
San Francisco, CA 220 I S • 4
*D, v.r, CO 54 • • 2
**Ws.hjngton, DC 14 I I • • 5
Jacksonville, FL 15 • • S S I 6
Niaini,FL 50 • • I S 5
Tan a,FL 16 I • • I • 5
Atlanta, GA 14 5 I 3
Louisvi l le,ICY 39 I • S I 5 5
90 S I S S I 5
‘I ntgorry Co., I 10 5 • I • • 5
Detroit, IC 77 . 1
• 8t.Pau1,) 5 13 • 3
Albany, NY 237 • 3
5 Buffalo, NY 44 5 3
**)t 4 .i Q1., NY 37 5 I 3
RewYorkCity ,NY 382 • • 5
• 5 Rochsst.r, NY 12 I S 3
13 S S • 5 5
**cjflCjp j, 00 65 I • I I 5
**C ev 5 p4, OH 80 • • • S S
• 5 Dayton,0 0 45 5 • S
25 • • 5
*Port1and , OR 20 1
Philadelphia, PA 94 • 2
Pittsburgh, PA 82 . 2
Chattanooga, TN 22 • I
Mm hi., TN 14 • I
Nashville, TN 17 1
Della., TX 21 I 2
**pajrfax Co., VA 12 • 5
Seattle, WA 39 2
TOTAL
24
24
16
17
21
10
1
1
114
COO — Coefficient of Haze
TSP Total Suspended Particulate (High-volwns sampler)
VIS — Visibility
PB — Particle Scattering (Integrating N.ph.lcmster)
* — City Index i. Operated by Stats but ii not Part of Btat.—wid. Index Syst.a
• * City Index is Part of State—wide or Regional Index Systea
39
-------
the shorter averaging time (2—hours) available from the
COH tape sampler. CO and SO 2 are the next most common
pollutants to be included in these indices —— 24 agencies
(73 percent) for each. The next most popular Pollutants
are oxidant (17 agencies, 52 percent) and NO 2 (16 agencies,
48 percent). Visibility is included in one agency’s index,
and particle scattering is the Only variable making up
another agency’s index.
When the air pollution indices used by States (or
regions) and Canadian Provinces are examined (Table 8), a
similar pattern emerges. The most common pollutants are
carbon monoxide, sulfur dioxide, and particulates (COH
and TSP). The least common pollutant is nitrogen dioxide,
with only two agencies —- Ohio and the District of Columbia — -
reporting it in their indices. The two Canadian Province
indices report different numbers of pollutants; the smaller
agency, Alberta, reports five air pollutants, while the
larger, Ontario, reports only two.
2. Index Classification System
To facilitate comparisons of the various air pollution
indices, an index classification system was developed.
40
-------
TABLE 8
VARIABLES USED IN STATE-WIDE AND PROVINCE-WIDE
AIR POLLUTION INDICES
Size
CO
SO 2
NO 2
Ox
COH
TSP
St a.te
District of Columbia
Minnesota
New Jersey
New York
Ohio
Total
14
37
170
237
228
•
S
•
•
•
5
•
S
•
•
•
5
•
•
2
•
•
•
3
•
•
•
3
•
•
2
Province
Alberta
Ontario
26
70
•
S
S
•
•
S
S
41
-------
Although nearly every city with a daily index employs a
different calculation method and different air quality
categories, it was found that the various indices could
be classified according to four criteria:
• Number of variables included in the
index.
• Calculation method used to compute
the index.
• Calculation mode (combined or uncornbjned)..
• Descriptor categories reported with
the index.
Categories which appear broad enough to group all the air
pollution indices were developed from these criteria.
Number of Variables . This number designates the
number of variables incorporated into an air pollution
S
index. These variables include the five NAAQS Pollutants
(excluding hydrocarbons), visibility, and particle scattering.
Calculation Method . According to the index classifica.. .
tion system, there are four calculation methods, three of
which (Types A, B, and C) involve the use o f an equation:
A. Nonlinear - Exponential function with coefficient
Or other nonlinear relationship. Coefficients
may be constant or may vary, but relationship
contains at least one variable raised to a power.
42
-------
B. Linear with nonconstant coefficients — Segmented
linear function of one or more variables or a
product of variables. There are no exponents,
but coefficients are different for different
ranges of the variable C 1 :
I K 1 (C)C 1
C. Linear with constant coefficients — Linear function
of one or more variables with coefficients that do
not change:
I
Coefficients may be chosen as K 1 = 1/C 5 , where
Cs is standard for pollutant, giving aproportionat
relationship; or they may be chosen as K 1 = 100/c 5 ,
which gives percentage relationship; or they may be
arbitrary and not related to any standard.
D. Actual concentration values — Conc ntrations
reported in scientific units (jig/ma, ppm) or
standard units from some commonly used measurement
technique (COH’s, etc.).
An agency reporting just its actual concentration values
is classified as not having an index and is not coded;
however, when the agency reports actual concentrations and
descriptor categories, its index is Type D.
The major nonlinear index (Type A) reviewed in this
study is 0RAQI. ’ ORAQI is designed such that when each
pollutant included in the index is equal to its standard,
the index value is 100 (its critical value). In general,
43
-------
the values for ORAQI may be determined from the nomograph
shown in Figure 3 Or computed from the ORAQI equation.
The nomograph is used by adding the pollutant concentrations
on the “Summing Columns”, placing this sum on the “Measured
Total” column, and then drawing a line to the proper point
on the “Unmeasured Pollutants” column. For example, when
the sum i-s 20, and there are no unmeasured Pollutants, the
index is 28.
Alternatively, One may calculate ORAQI using the
equation shown in Table 3. If less than five pollutants
are used in the index, a different coefficient must be
used. For example, for sulfur dioxide and particulate
matter the equation is:
[ /so
L’ 4 ” 42 ( , O.l0 + 150)]
where SO
o o = the 24—hour average concentration
of sulfur dioxide (ppm) divided
by a 0.10 ppm standard
= the 24—hour average concentration
of suspended particulate matter
(iig/m 3 ) divided by a 150 1g/m 3
standard,
Figure 4 shows a plot of this equation for constant particu-
late matter (PM) concentrations (75, 150, and 225 .ig/m 3 ).
44
-------
(7)
— — 1000
— — 600
— — 600
S0x.c0,Pu — —
——400
OX,SOx,PM — —
— 300
oo 0X N0 2 .C0 — —
N0 2 C0.PM — —
100 0X,N0 2 .PM — —
= 60 OX .C0 — —
: 60 C0 .PM — —
— OX,PM——
— S Ox,NO 2 ,CO — —
= 30 OX.SOx.NO 2 — —
S Ox.N0 2 .PM — —
SOx.c0 — —
0X.s0x — —
— —
=10 N 0 2 ,CO— —
—8 V OX,N0 2 — —
— N0 2 ,PM — —
co— —
— ‘— OX— —
—4 —
— — 3 \\S0X.N0 2 — —
son——
N ——
AIR NONE — —
QUALITY UNMEASURED
INDEX POLLUTANTS
(6)
ORNL-DWG 7,-9e9oR
Ce,
0X.S0x .C0 — —
=
(1)
(2)
— — 0.35
(3)
— — 0.70
(4)
—
(5)
—
—
70 — —
— =
—
— —
—0 )0
—
— —
-—
— —
-=
— —
—
—
— —
50 — —
— 0.09
— 0.30
— — 0.60
—
— — 450
40 — —
—
—008
==
.
I
1:400
—
30——
—
.—
—
—
— 0.25
— - 0.50
—
— —
20—
:
—
—
—
=
—
:
—
— 0.06
—
— 0.20
—
0.40
—
40——
—
—
—
— —
—
— —
:—°°
::
=
— :
— —
— —
—
— — 0.04
— — 0.15
— —
— —
—
0.30
—
— =
— —
—
— —$0
—
— — 200
— —
5——
—
— —
STAPdARD
0.03
=—O. 02
0. (0
==
—0.20
—450
4 - —
3—
—
:
5
— —
—
1:$00
—
—
—
—
— 0.05
— 0.40
— —
2——
— — 0.04
— —
— =
— —
— — 50
——0
— —O
— =0
— —O
CARBON
— ::
PARTICULATE
OXIDANT
(OX)
SULFUR NITROGEN
OXIDES DIOXIDE MONOXIDE MATTER
(SOx) (NO 2 ) (CO) (PM)
-
I — —
MEASURED
TOTAL
N
SUMMING COLUMNS
Figure 3. NomograPh for determining the Oak Ridge Air Quality Index (ORAQI).
-------
200
175
150
125
100
0
75
50
25
0
0
0.05 0.10 0.15 0.20 025
SO 2 , ppm
Figure 4. ORAQI function for sulfur dioxide and particulate matters
46
0.30
-------
The slight curvature (nonlinearity) of the lines is due
to the exponent. When the two pollutants are exactly
equal to the standards (0.10 ppm for SO 2 , 150 jig/rn 3 for
PM), the index reaches its critical value of 100 (Point A).
However, the index can be 100 under many other circumstances
as well. For example, if the SO 2 concentration is 0.05 ppm.
(below the standard), while the particulate concentration
is 225 jig/rn 3 , the index is still 1=100 (Point B), even
through only one standard is exceeded.
A more important problem for this index is “eclipsing” ——
the case when one pollutant exceeds its standard without
the index exceeding its critical value. Suppose, for example,
the SO 2 concentration is 0.12 ppm (above the SO 2 standard)
and the particulate concentration is 75 jig/rn 3 (Point C).
Then the index value is 180, and the SO 2 standard is
exceeded but the index remains below its critical value.
All possible index values for SO 2 eclipsing are shown in
the “SO 2 Eclipsing Region” of Figure 4. A similar region
can be identified for the case where particulate matter
exceeds its standard and SO 2 is below its standard.
The Type B segmented linear calculation method (linear
with nonconstant coefficients) is much simpler than the
47
-------
Type A nonlinear method. Figure 5 shows a plot of the
segmented linear function for carbon monoxide used in the
Washington, D.C. index. Each pair of values (CO , I) are the
coordinates of a breakpoint (represented as a dot). The
resulting function Consists of five straight line segments,
each with different slope. The index value for any con-
centration of carbon monoxide can be determined directly
from the curve. For example at 80 ppm CO, the index value
is 200.
In the Type C (linear with constant coefficients)
Calculation method, the index value is a simple linear
function of a pollutant concentration. The Type D method
reports actual Pollutant concentrations and therefore uses
no index equation.
Calculation Mode . Another important aspect of the
calculation method is how the index variables are treated.
Does the agency report individual index values for each
variable? Does the agency report an index value only for
the variable which has the maximum value of all the index
variables? Does the agency’s index c mbine the variables
in some fashion? Thus, the mode identifies whether the
index is co jned or UnCombined. Uncombjned indices include
48
-------
100
co Concentration, ppm
Figure 5. Exempts of a segmented linear function for carbon monoxide
49
I
(00,100)
(35,50)
100
0
0 20 40
•INDEX
BR EAKPO INTS
80
-------
those in.the individual or maximum mode category; combined
indices are sometimes referred to as aggregated indices.
The mode is indicated by appending a subscript to the
calculation method classification.
1. Individual — An index value for each variable
comprising the index is reported.
2. Maximum — Only the index value for the maximum
variable is reported.
3. Combined — The index variables are aggregated,
through some type of mathematical manipulation,
to give one index value. (This mode exhibits
the eclipsing effect.)
Descriptor Categories . The descriptor categories
result when the index range is subdivided into several
categories. The words assigned to these categories give
a qualitative description of the air quality. For example,
an index may list 0—25 as “good,” 26—50 as “satisfactory,”
51—99 as “unsatisfactory,” and 100—199 as “unhealthy.”
If an index reports actual pollutant concentrations, then
several concentration ranges may be used for the descriptor
categories, Index descriptor categories can be based on
standards, episode criteria, or an arbitrary basis:
A. Standards — The category breakdown is based
on Federal, State, or local ambient air
quality standards -— for example, index
values above 100 exceed the Federal Primary
50
-------
NAAQS and those below fall into several
categories partially based on the Federal
Secondary NAAQS. If actual concentrations
are reported, then these concentrations are
related to the standards.
B. Episode Criteria — Type A (above) is extended
to accommodate index values above 100. These
values are based on the Federal, State, or
local episode criteria —- for example, 100
is the Alert Stage, 200 is the Warning Stage,
etc. For indices reporting actual pollutant
concentrations, these concentrations are
related to the episode criteria.
C. Arbitrary — Categories of this type are
semiempirically based and usually designed
to fit the specific requirements of the
index values, This classification also
covers indices with no descriptor categories.
Summary and Example Application of the Index
Classification System . The result of the classification
system is a four—character code which describes any index.
Using the system, the Oak Ridge Air Quality Index (OR.AQI)
is coded as “5A 3 A” (Figure 6). The number “5” indicates
that the index includes five pollutants or variables;
A 3 denotes the calculation method and mode (i.e., it is
nonlinear and the variables are combined to give one index
value); “Afl refers to the basis for the descriptor categories
(i.e., the categories reported with this index are based
on the NAAQS).
51
-------
Calculation
Method 1
I
5AA
Number
of Mode 2
Pollutants
Basis for Descriptor Categories 3
B.
( ‘S
n.
Nonlinear
Segmented linear
Linear
Actual Concentrations
2/ 1: Individual
2: Maximum
3: Combined
A:
B
C:
Standards
Episode Criteria
Arbitary
t )
Figure 6. Index Classification System
-------
3. Results of Classification
The classification system described in the previous
section was applied to all the indices reviewed in this
study.
Indices Reported in the Literature . Table 9 shows
the classification the eight indices reviewed in Chapter IV.
Seven of the eight use a corr ined calculation mode (Type 3),
and five of these use a nonlinear (Type A) calculation method.
The general complexity of the “A 3 ’ type index equation, with
its inherent eclipsing effect, may have contributed to the
limited use of these indices by local air pollution control
agencies.
Indices Reviewed in the Survey . Application of the
index classification system to the 30 index systems reviewed
*
in the survey revealed 15 basic types (Table 10). To
simplify comparison of these index types, they are grouped
according to their calculation method. Only Type B has no
discontinued indices. The three discontinued indices
apparently were dropped because they were not consistent
with air pollution levels as preceived by the public.
*A basic type refers to the calculation method and
descriptor categories, but not to the number of variables.
53
-------
TABLE 9
CLASSIFICATION OF iNDICES REPORTED IN THE LITERATURE
Index - Classification
Oak Ridge Air Quality Index (ORAQI) nA 3 A, n1 to 5
Mitre Air Quality Index (NAQI) riA 3 A, ri l to 5
Extreme Value Index (EVI) nA 3 A, n1 to 4
Ontario Air Pollution Index (API) 2A 3 B
Green’s Combined Index (CI) 2A 3 C
Combustion Products Index (cPi) IC 1 C
Air Quality Index (AQI) nC 3 C, n l to 5
PINDEX 7C 3 C
54
-------
TABLE 10
THE 15 INDEX TYPES ANI) THEIR USERS
Type
Users
A 1 C Detroit, Oklahoma City, ” Memphis
A 3 A Tampa
A 3 B Minnesota, Ontario
A 3 C Alberta
B 2 B Baltimore, Ohio, Seattle, Washington, D.C.
8 2 C Denver
B 3 C Philadelphia
C 1 C Nashville
C 3 B Louisville, Pittsburgh, Dallas
C 3 C Jacksonville, Miami, Atlanta, Phoenix ”
D 1 A New Jersey, New York State
D B Anaheim, Los Angeles
D 1 C Connecticut,W Portland, Chattanooga
D 2 A New York City
D 2 B San Francisco
‘Discontinued index
55
-------
City/County Indices . Classification of the various
indices used by the survey respondents revealed a striking
diversity and few clear patterns (Table 11). A detailed
analysis, however, reveals some important results.
Of the 33 city/county agencies, 13 (40 percent) include
five variables in their index calculation (Table 12). This
is due mainly to the fact that five agencies in Ohio and
four in the Baltimore—Washington, D.C., area use indices
incorporating five variables. In fact, each of these nine
agencies used the 5B 2 B type of index.
TABLE 12
NUMBER OF VARIABLES INCLUDED IN INDEX CALCULATION
Number
of Variables
Number
of Agencies
Percent
1
5
15
2
5
15
3
8
24
4
1
3
5
13
40
6
Total
1
33
3
100
56
-------
TABLE 11
SUMMARY OF INDEX CLASSIFICATION RESULTS
Number of
Variables
1 23456
CaIcutat on
Method
ABC D
Mode
1 23
Descriptor Categortes
Type
ABC
Number
CitylCounty
Anaheim, CA
Los Angeles, CA
San Francisco. CA
Denver, CO
Washington, DC
Jacksonville, FL
Miami ,FL
Tampa, FL
Atlanta, GA
Louisville, KY
Baltimore, MD
Montgomery Co.. MD
Detroit ,M l
St. Paul, MN
Albany,NY
Buffalo .NV
Mineola ,NY
New York City. NY
Rochester, NY
Akroa,OH
Cincinnati, OH
Cleveland. OH
Dayton, OH
Toledo, OH
Portland, OR
Philadelphia, PA
Pittsburgh, PA
Chattanooga, TN
Memphis, TN
NashvilIe TN
DaIlas,TX
Fairfax Co.. VA
Seattle, WA
•
•
S
I
I
•
•
•
•
•
.
•
•
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•
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1
.
•
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,
•
•
S
.
5
‘
•
,
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s
.
•
3
6
5
7
None
5
6
None
4
8
5
4
3
3
3
4
3
12
12
i
12
12
5
3
6
4
4
4
4
7
3
StatelRegion
tiistr,ctof Columbia
Minnesota
Newjersey
New York
Ohio
I
•
I
•
I
•
I
•
•
I
S
S
•
S
•
S
•
S
7
4
4
3
12
Province
A lb a
Ontario
•
I
•
‘
5
5
57
-------
Despite the heavy influence of these nine agencies
on the data, Table 13 shows that the segmented linear
function (Type B) and the actual concentrations (Type D)
are the most popular calculation methods (37 and 30 per-
cent, respectively). Only four cities (13 percent) use
a nonlinear index calculation, suggesting a definite
preference for the less complex calculation schemes.
TABLE 13
INDEX CALCULATION METHODS
Nethod
Number
of Agencies ”
Percent
A.
Nonlinear
4 (3)
12
(9)
B.
Linear with nonconstant
coefficients
12
37
C.
Linear with constant
coefficients
7
21
D.
Actual concentration
values
10 (11)
30
(33)
Total
33
100
‘ Numbers in parentheses are the reclassification of
agencies using two methods (see text).
This preference is also evident in St. Paul which uses a
nonlinear index (Type A: ORAQI), but in addition reports
58
-------
actual concentration values (Type D). If St. Paul were
reclassified as Type D (shown in parentheses, Table 13),
then Only three (9 percent) of the agencies use the
fl nhinear type calculation method.
Table 14 shows that the “maximum” mode of calculation
was used by 13 (40 percent) of the agencies. Another 11
agencies (33 percent) used the “individual” mode, thus
indicating a preference for uncombined (73 percent) versus
combined (27 percent) indices. However, Jacksonville and
St. Paul use both the individual and combined mode. If
TABLE 14
I iODE OF INDEX CALCULATION
Mode
Number
of Agencies ”
Percent ”
1. Individual
2. Maximum
3. Combined
Total
11 (13)
13
9 (7)
33
33 (40)
40
27 (20)
100
“Numbers in parentheses are the reclassification of
agencies using two modes (see text).
59
-------
they were reclassified as using the individual mode (as
shown in parentheses, Table 14), then only seven (20 per-
cent) of the agencies use the combined mode and 80 percent
use the two uncombined modes.
Table 15 shows that 22 agencies (67 percent) used
index descriptor categories based either on standards or
on episode criteria; the remaining one—third used arbitrary
categories.
TABLE 15
BASIS FOR INDEX DESCRIPTOR CATEGORIES
Category Basis
Number
of Agencies
Percent
A. Standards
B. Episode criteria
C. Arbitrary
Total
7
15
11
33
21
46
100
The number of categories used in the indices is shown
in the histogram of Figure 7. There appears to be a definite
preference for three or four descriptor categories. However,
there does not appear to be any tendency toward using the
60
-------
C.)
It
E
z
0 1 2 4
6 7 8 9 10 11 12 13 14
Number of
Figure 7. Histogram of the number of
county air pollution indi s.
CategoriE
desaiptor categories used in
24%
12%
15%
6%
4
3
2
1
0
9%9%
3%
U.S. city and
-------
same words for the descriptor categories. A total of 41
different words (Table 16) are used in the descriptor
categories of the 28 U.s. index systems. Indices containing
the more common words are shown in Table 17. These words
were selected by weighting each descriptor according to its
frequency of occurrence (Table 16). It is interesting to
note that certain words occur more frequently in multi—
pollutant indices and other words more frequently in indices
involving particulate matter.
State and Province Indices . Due to the small sample
size, only five States and two Provinces, no detailed
analysis was possible. However, examination of Table 11
shows that all of the States report at least three pol-
lutants in their index; two States report all five NAAQS
pollutants. Since Minnesota reports individual pollutant
concentrations in addition to its combined index (ORAQI),
all States indices can be classified as using the segmented
linear or actual concentration calculation methods, while
the calculation mode is either individual or maximum. Thus,
both the States and cities make limited use of the more
complex, nonlinear combined indices (Type A 3 ). On the other
62
-------
TABLE 16
THE FREQUENCY DISTRIBUTION OF THE 41 WORDS USED
FOR DESCRIPTOR CATEGORIES
Heavy 11 Normal 2 1
Good 10 Stage 1 2
Light 9 Stage 2 2
Unsatisfactory 7 Stage 3 2
Unhealthy(fu l) 6 Very Heavy 2
Moderate 6 Warning 2
Emergency 5 bove Average 1
Poor 5 Acute 1
Extremely Heavy 4 Average 1
Fair 4 Below Average I
Medium 4 Endangerment 1
Satisfactory 4 Extremely Poor 1
Severe 4 Harmful 1
Alert 3 High 1
Clean 3 Low 1
Extremely Light 3 Significant 1
Very Poor 3 Slight 1
Acceptable 2 Very Dangerous 1
Dangerous 2 Very Good 1
Excellent 2 Very Light 1
Hazardous 2
63
-------
TABLE 17
INDICES USING THE MORE COMMONLY OCCURRING WORDS
IN DESCRIPTOR CATEGORIES
Multipollutant Indices
Indices for Particulate Matter
Only
New York City
Detroit. Memphis,
(Oklahoma
City)
Good
Extremely light
Acceptable
Light
Unsatisfactory
Medium
Unhealthy
Heavy
Extremely heavy
Minnesota, New Jersey
Chattanooq a
Good
Satisfactory
Light
Unsatisfactory
Moderate
Unhealthfu].
Heavy
Alert
Miami
Good
Normal
Moderate
Heavy
Severe
64
-------
hand in Canada there appears to be a preference for this
type of index, with both Alberta and Ontario using non—
linear combined indices.
4. Comments from Respondents
Some insight into the reasons for the great variety
of air pollution indices was gained by examining the
subjective views of th survey respondents. Their comments
were assembled by the authors from notes taken during the
informal telephone conversations with each agency (Appendix C).
Since they do not represent official agency views, they are
listed anonymously.
Agencies Using Indices . As one might expect, most
individuals from agencies now using indices expressed
satisfaction with their own index, although one respondent
acknowledged that most people probably do not follow the
index in the newspapers. There was widespread opinion that
the numbers expressed by indices are not necessarily
meaningful, and one agency stated that its index was not
developed on any scientific basis and was not intended as
such. In general, indices were viewed as an informational
tool designed to advise the public as to the severity of
65
-------
air pollution levels, but not to convey any information
about the deleterious effects of air pollution. Some
agencies felt that the layman does not understand the
technical language of air pollution, and thus indices
fulfill an important need by communicating with him in a
nontechnical way. However, in many cases the public may
not understand the index either. One agency using the
complex ORF QI index attempted to solve this problem by
distributing a public information bulletin on the subject.
A number of the respondents expressed concern about
the lack of spatial representativeness of index values.
This concern apparently reflects a lack of representativeness
of the monitoring data used to calculate the index.
Several agencies had found it necessary to make major
changes in their indices within the past 5 years. These
agencies indicated they had some difficulty overcoming the
public confusion which resulted from these changes, par-
ticularly where the changes were great. One such agency
stated that the introduction, right now, of any new indices
“would bury us.” Another agency changed its index from
the combined form to a maximum type because the combined
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index gave misleading results —— ‘ow values when one
standard is violated and other pollutants are low, or
high values when all pollutants are high but no standard
is violated.
Agencies Not Using Indices . The diversity of opinion
was wider among persons in agencies which do not presently
use air pollution indices. Respondents often expressed
dismay about the large number of air pollution indices in
existence: With so many different air quality indices
around, “people really can get confused when they move
from city to city.” Many respondents felt it better to
familiarize the public with the scientific notation for
pollutant concentrations —— j.ig/m 3 , ppm —- than to teach
the public how to understand an index. Some agencies felt
they would adopt an index if they could find one that was
understandable and agreeable to all, but that there is not
yet a sufficient scientific basis for such an index. Some
of the reasons offered for not adopting an air pollution
index were purely practical -— not enough monitoring data
to implement the index or not enough staff to compute the
index. The problem of finding an index that is consistent
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with the public’s perception of air quality was cited
frequently as a reason for not using an index. One agency
used ORAQI for several years but found it did not correlate
well with observed air quality and resulted in many complaints;
thus, it was abandoned:
We soon found that [ index values] did not relate
to what the public saw. Many times, mountains
surrounding [ the city] would be barely visible
during winter months and yet the index would
register in the light air pollution range. This
resulted in considerable controversy concerning
the validity of the index with the general public
and the news media. We went to considerable
length to explain that the index was a combination
of a number of pollutant levels and that the
gaseous pollutants could be low and there could
still be sufficient fine suspended particulates
in the air to obscure visibility, resulting in
a low combined index. After one year of increasing
problems with the combined index which included
several attempts to modify it, we discontinued its
use.
Another agency suggested that the decision of whether or
not to use an index probably depends on the level of public
education, and that any approach is satisfactory as long
as the public fully understands it. Another agency felt
that it was preferable to forecast tomorrow’s pollutant
values (or index values) than to announce today’s or
yesterday’s values, as many indices are designed to do.
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A common reason given for riot using an index had to do
with the lack of clear understanding of indices by the
public, leading to confusion and misunderstanding. One
agency noted that most of the current indices, because
they are arbitrary, are really not interpretable. As such,
this respondent felt that most indices represent a “non-
understandable, nondimensional nun ber.” One agency
discontinued its index because the news media “sensationalized”
it by reading more into the index than was intended: “The
index is now at 80 and when it gets to 100 you will have to
start worrying.”
Criteria for a Uniform Index . Although some respondents
expressed much skepticism about the understandability and
meaningfulness of air pollution indices in general, par-
ticularly about con ined air pollution indices, there was
general agreement that prevailing confusion might be reduced
if the Federal Government were to develop, endorse, and
support a single, uniform air pollution index. Only two
dissenting arguments were offered against this concept:
One respondent felt that adoption of a uniform index would
make comparisons of air pollution levels in different
cities too easy, creating hostility among the cities.
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Another respondent felt that each index should be tailored
to the public it serves and therefore should be different
in different cities. From the comments, it appears that
one of the most serious obstacles to adopting any standard-
ized index is the fact that most cities already have one
and would have difficulty changing it to conform to some
uniform system. The process of re-educating the public
poses a difficult problem which would need to be addressed.
Another serious problem lies in formulating an index that
is truly satisfactory to these agencies and to their public.
From the viewpoints expressed by respondents, it appears
that any uniform air pollution index would have to possess
the following desirable features:
• Is easily understood by the public
• Is not inconsistent with perceived air
pollution levels
• Is spatially meaningful
• Includes major air pollutants (and
expandable to include future pollutants)
• Is calculated in a simple manner using
reasonable assumptions
• Rests upon a solid scientific basis
• Relates to ambient air quality standards
and goals
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• Relates to episode criteria
• Exhibits day-to—day variation
• Can be forecast a day in advance
(optional)
5. Display and Dissemination Techniques
The methods most frequently used to report air
pollution indices to the public include the usual com-
munications media: newspapers, television, radio, and
telephone recordings. Of these, newspapers are the most
COmmon dissemination method, and they give air pollution
indices the greatest coverage. Appendix D gives several
examples of newspaper index reports; other examples can be
found in recent reports by Cullen -” and Reidy. ’ 1 Some
newspapers give on y a narrative description, while others
include a bar graph or table with a brief explanatory note
of each day’s index.
The next most prevalent means of reporting daily
indices appears to be television. Television reports may
give only the index value or include visual displays
accompanied by a short verbal explanation. Of course,
radio is limited to verbal reports. Index reporting formats
vary not only from city to city but also within each city.
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Thus, two newspapers in the same city (for example, Albany,
New York -— see Appendix D) may use an entirely different
format to report the same index; alternatively, one news-
paper may not report the index at all. The same variation
occurs in television and radio reports.
The diversity in reporting of indices apparently results
largely from lack of involvement by the air pollution control
agency in deciding how its index is to be reported to the
public. Several agencies interviewed in this survey specif-
ically stated that they do not recommend a format for
reporting their index to the public. However, a few agencies
indicated that they suggest display formats and recommend
their use. In those agencies recommending no particular
format, the resulting flexibility may lead not only to
variations in who reports the index, but in how it is
reported. If carried too far, this could have undesirable
effects: in one city, for example, a television reporter
“sensationalized” the index, causing the agency to discontinue
its use altogether (see Section 4 of this chapter).
The use of telephone recordings (codophones) to
disseminate air quality information generally is undertaken
only by air pollution control agencies, although some
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citizens’ groups operate telephone air pollution information
services for persons with respiratory diseases. Those
agencies using telephone recordings do so for the convenience
of the news media and the public. The information on these
recordings is updated regularly and, in contrast to news-
papers and television, telephone recordings use a specific
format, similar to that used by the telephone companies
for the weather report.
In summary, there is much diversity in the way the
various media report indices. It is not clear .that these
diverse approaches have solved the difficult problem of
clearly relating an air pollution index to air pollution
levels and making the result understandable to the layman.
This situation possibly could be improved if the media
used a standard reporting and display format. Such a
format could be structured to facilitate public education
about the origins of air pollution, its effects, and methods
of Control.
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CHAPTER VII
A CASE STUDY OF THE DEVELOPMENT
OFA COMMON AIR QUALITY INDEX
FOR A TRI-STATE AREA
The region comprising the cities of Steüberiville, Ohio;
Pittsburgh, Pennsylvania; and Wheeling, West Virginia, has
pioneered in establishing cooperative efforts to abate air
pollution. In 1970, the three States were the first to
establish an interstate compact to control air po11ution. ”
The compact was designed to curb emissions along the Ohio
River where there are major chemical, steel, aluminum, and
metallurgical plants, as well as electric power generating
stations.
At present, three different air pollution indices are
used in the region. During late 1974, representatives from
the Ohio Environmental Protection Agency, North Ohio Valley
Air Authority, Allegheny County Bureau of Air Pollution
Control (Pittsburgh), West Virginia Air Pollution Control
Commission, and Wheeling Air Pollution Control Board met
to discuss their indices, identify the problems associated
with developing a common index, and recommend criteria for
a common index.
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The main reason for developing a common index within
this tn—State region is to alleviate confusion resulting
from public exposure to the three different indices. A
common index could present a clear and unified reporting
system of the air quality in the region.
These three indices are analyzed in detail in
Appendix B. Briefly! Ohio’s index reports the maximum of
five subindex values which are calculated using segmented
linear functions with nonconstant coefficients (Type 5B 2 B).
The subindex for each variable is a percentage of the Ohio
ambient air quality standard. The 12 descriptor categories
of the index are based on the Ohio standards and alert
criteria, in which a value of 100 indicates that the
pollutant concentration has reached the Ohio ambient air
quality standard.
The index used in Pittsburgh and surrounding Allegheny
County combines 502 and COH in a linear fashion with constant
coefficients (Type 2C 3 B). The index is the sum of the ratios
of the pollutant concentrations to their standards, multi-
plied by 50. There are six descriptor categories based on
the Allegheny County episode criteria. Due to the way in
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which the two subindices are combined, a range of values
(84I lll) signifies onset of the first stage alert.
West Virginia, which is presently considering adoption
of a State-wide index, is awaiting the outcome of the
present discussions regarding development of a common
tn—State index. As an interim measure, the city of
Wheeling recently instituted ORAQI. This index uses
nonlinear exponential function with a constant coefficient
to calculate index values from the sum of the conceritratiOfl/
standard ratios (Type riA 3 A, with ri= 1, 2, 3, 4, or 5). The
exponent, 1.37, and the coefficient, 5.7, are chosen to
give index values which relate to the secondary NAAQS. The
index also may be calculated using a nomograph. ORAQI has
six descriptor categories, and an index value of 100 is
intended to mean that all pollutant concentrations in the
index have reached the secondary standards. However, due
to the combined nature of the index, values of 100 may be
obtained under many different conditions.
The problems in developing a common index from three
indices which incorporate different numbers of pollutants,
calculation schemes, and descriptor categories are immense,
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but not necessarily insurmountable. The three agencies
were acutely aware of the complexity of the task and the
extensive cooperation that would be required to meet the
goal.
One of the authors attended the second meeting of
officials from the three agencies. This meeting explored
the overall problems involved in developing a common index.
Each agency was asked to discuss its index and to provide
thoughts on developing possible criteria for a common index.
The following summarizes the most important points presented
by each agency.
West Virginia
• An index value of 100 should identify a
significant point in the descriptor
category scheme (e.g., violation of the
short-term primary NAAQS or one of the
Federal Episode Criteria).
• Indices containing too many subindices
(i.e., combined indices) confuse the
public and underemphasize the contribution
of the subindex with the highest concen-
tr at ion.
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• Because the present NA1 QS do not consider
synergism, a synergism term may not be
appropriate in the index. However,
synergistic S0 2 -COH and S0 2 -TSP terms are
a part of the Federally recommended
episode criteria.
• Using two indices, one for stationary
source pollutants and one for mobile
source pollutants, would inform the public
of the two major categories of air pol-
lution sources covered by different en-
forcement policies.
• The index would provide useful infcrrna—
tion about the effect of enforcement
activities in the tn—State region.
• The index should be sensitive to the
daily changes in air quality.
• In addition to issuing a common index,
it may be useful to also issue a running
annual average of the index, as well as
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the number of days the standards have
been exceeded.
• Adoption of a corrunon index will require
the States to establish similar episode
criteria.
Ohio
• Any index must maintain its credibility
with the public; that is, it must reflect
what is perceived and give a true
representation of regional air quality.
• The index calculation should take all pol-
lutants into consideration and be able to
incorporate new pollutants. However the
index (1) should not include combined
(synergistic) terms for which standards do
not exist, and (2) should not be structured
to allow identification of individual sources.
• The problem of obtaining spatially repre-
sentative index values may be partly solved
by reporting mean or maximum values over
the region.
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Allegheny County
• The numerical range of descriptor categories
for the index must take into account the
fact that future air quality levels (and
hence index values) will be lower than
those presently experienced.
• The primary and secondary NAAQS and the
recortimended Federal Episode Criteria
should be used in defining the descriptor
categories.
• Separate indices for mobile sources and
stationary sources have the advantage that
they educate the public about pollutant—
source relationships. A separate index
for each pollutant would not be as ef-
fective an educational tool.
• The S0 2 —COH index now used in Allegheny
County is adequate for most of the year,
but it could be supplemented in the summer
months by an index emphasizing the presence
of oxidant.
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In the general discussion that followed, several
concrete recommendations were made:
• The three jurisdictions should develop a
common system for the descriptor cate-
gories accompanying the index. (It was
noted that each jurisdiction would have
some problems in adapting its present
system to any new system. Such a change
should be permanent —— not to be changed in
the near future by Federal regulations.)
• The index should be calculated in relat ion—
ship to air quality standards, with possibly
a second index for the running annual
average value of the index.
• Public information (daily index reports) and
official air pollution control activities
should not be reported together.
• Further efforts to develop a common index
should also include the States of
Pennsylvania, Kentucky, and Maryland.
At the end of the meeting tentative agreement was
reached on the following point:
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• The value of 100 on the tn—State air
quality index scale should indicate
that the short—term primary NAAQS for
at least one air pollutant has been
violated.
In summary, this second meeting enabled the three
agencies to learn which modifications will have to be made
in existing indices if a common index is adopted. In
addition, the discussion of the general criteria for such
an index laid the preliminary ground work for development
of a uniform index to serve the three States.
The third meeting of the tn—State agency officials
took place in Columbus, Ohio, on January 30, 1975. The
meeting was a general review of the previous meeting with
some additional discussion on the following points:
• The three main areas of agreement required
to establish a common ndex are the selection
of a numerical scale, the definition of
category divisions and descriptors, and
the determination of how the index should
relate to the episode criteria presently
used by Ohio and Pittsburgh.
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• Each State reviewed the official decision—
making process it must go through before
changing its current index.
• Each agency expressed the hope that a
common index system could be operational
by the end of summer 1975.
As of July 1, 1975 no final decisions had been made on
adopting a common tn—State index.
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CHhPTER VIII
CONCLUS IONS
Air pollution indices perform a service by giving
residents of urban areas an indication of day—to—day
changes in air quality. However, air quality levels
observed in urban areas also are of interest to the Nation
as a whole because they provide an indication of the Nation’s
progress toward cleaner air and can allow comparisons of the
air pollution problems in different cities. Such information
is of particular importance to national decision makers.
It would be helpful if the daily air pollution indices
in common use facilitated interpretation of national air
quality. Unfortunately, they appear to impede it, and
their diversity appears to confuse the issue. With so
many different indices in use in metropolitan areas, it
becomes impossible, on a national level, to gain insight
into metropolitan air pollution levels by examining the
indices. Further, with little assurance that the data on
which each index is based are of the same quality and
manipulated in the same fashion, it becomes difficult to
interpret the meaning of each index and virtually impossible
to use the index to compare metropolitan air pollution
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problems or to assess air quality trends over time. While
a given index might be suitable for application on a
metropolitan scale, all the indices, when talcen together,
give a picture of confusion.
The need is clear for a uniform air pollution index
which can be used nationwide. From the comments of air
pollution control agency personnel, there is evidence that
a standardized air pollution index system, or a uniform
air quality reporting format, would be both beneficial and
welcome. In a recent report, ” the National Academy of
Sciences recommended that a “uniform national system of
air quality indices be developed and adopted.” However,
one major question remains unanswered: What should be the
structure of the uniform index?
As a first step toward refining this structure, this
study has identified criteria for a uniform air pollution
index (Chapter VI, Section 4). Using these criteria, along
with the survey data and major findings, it has been possible
to develop two prototype air pollution indices —— the
Standardized Urban Air Quality Index (SUAQI), and the
Primary Standards Index which are discussed in Appendices
E and F. They are offered to provide examples of the
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characteristics that such an index should possess, and
should be viewed only as a starting point from which
to develop an acceptable nationwide index.
The great variation in existing indices suggests there
may be great variation in monitoring practices as well. If
a standardized urban air pollution index were adopted, the
index would not be comparable from city to city unless the
data on which it is based were of the same high quality.
Thus, quality assurance (proper measurement methods,
instrument configuration, laboratory practices) is critical
if the index is to have uniform meaning and applicability.
One approach to help insure that the data used in the index
are of adequate quality is to provide standard procedures
for the way in which the agency collects the data for the
index. Ultimately, each city might have its own standardized
“index reference site,” which conforms to these procedures.
A first step in this process is for the Federal Government
to publish an Index Monitoring Guidelines document, which
would specify such factors as: (1) pollutants used in the
index, (2) method of calculation, (3) descriptor categories,
(4) averaging time for the pollutants, (5) period of the day
in which averaging times should begin, (6) measurement methods
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to be used for each pollutant, (7) monitoring system
configuration (for example, inlet diameter and flow rates),
(8) height of sampling probe, and (9) procedures for
selecting monitoring station sites.
Decisions as to the nature and structure of any uniform
index are complex and should rest on informed judgment. The
data base developed in this study should provide much of
the information required to arrive at these decisions. Since
the selection of a uniform index is largely a policy matter,
it is recommended that a Federal interagency committee be
formed to review this study, along with the relevant data,
and to arrive at conclusions as to the feasibility of
establishing a national air quality index or data reporting
format. This interagency committee also should oversee
the development of the Index Monitoring Guidelines document,
which would be used to familiarize State and local air
pollution agencies with the nature and characteristics of
the standardized air pollution index.
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CHAPTER IX
FUTURE RESEARCH NEEDS
Although this investigation has provided much information
that will be of assistance in establishing a uniform index or
data reporting format, this study is by no means the final
step in such a process. Further research should be under-
taken to improve knowledge on important related topics:
• Scientific Basis
• Public Attitudes
• Index Reporting Systems
• Monitoring Siting
• Follow-up Study
1. Scientific Basis
One possible explanation for the great diversity of
air pollution indices in current use is the lack of a
uniform scientific basis. Knowledge of the relationship
between observed effects and air pollutant concentrations
over a wide concentration range is very limited. The problem
of generating a meaningful dose—response relationship from
studies of health effects, for example, is extremely
formidable. Possibly, future research on the health effects
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of air pollution may enable dose—response functions to be
established on which a more scientifically defensible index
could be proposed. Lacking such functions, some agencies
choose a linear calculation method, some a segmented linear
method, and some a nonlinear method. Because there is no
solid basis for any one approach, indices become arbitrary
in design and subject purely to the judgment of the air
pollution agency involved. Progress toward solving this
problem could be achieved by additional scientific research
on the effects of air pollutants on humans, on plants and
animals, and on materials.
2. Public Attitudes
In the authors’ experience, there appears to be much
controversy among members of the professional air pollution
community as to the meaning and significance of air pollution
indices. Some of this controversy results from varied as-
sumptions about the public’s attitudes toward indices. Some
air pollution professionals believe that indices are inter-
preted by the public to mean that the air is Thealthy” or
“unhealthy” and that members of the public actually may
modify their behavior due to index reports (that is, they
may stay indoors, take trips, or reduce their physical activity).
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Other air pollution professionals feel that indices are
interpreted by the public as a relative measure of the
clarity of the air (for example, as a day to day measure
of visibility) with little other significance.
Among the agencies, some felt that members of the
community paid considerable attention to the index, were
pleased with it, and used it in their daily activity; other
agencies felt that their index confused the public but was
nevertheless necessary because the community wanted a
simple indicator of air pollution; still other agencies
felt that the public probably didn’t even know the index
existed.
This lack of agreement about the community’s feelings
toward indices suggests there is need to obtain more knowl-.
edge about the public’s perception and attitudes toward
indices than has been possible in the present study. Do
high index values, for example, actually cause changes in
behavior on the part of individuals? Such behavior changes
could, in turn, affect daily fuel consumption (increased
use of indoor lighting and appliances; increased use of
energy for travel) and have other social costs. In those
communities where high index values occur frequently,
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residents may be more inclined to purchase electrostatic
precipitators, to limit their outdoor physical activity,
or to advise other potential residents not to move there.
They may even consider moving elsewhere —— to a city where
*
air pollution is less a “problem.” The limited information
available about the public’s perception of air pollution
indices suggests that future research to examine, in—depth,
the public’s views toward indices and the use they make of
these indices would be helpful. The data of the present
study should provide a sound basis for selecting the cities
in which such an attitude study could be carried out. Such
a study might possibly include three or more communities,
each having very different indices, with opinion interviews
of a random sample of respondents. It might examine the
ways in which they understand environmental problems in
general, their level of exposure to the media, and the manner
in which indices are interpreted and are useful to them.
*
During this study, one of the authors was contacted
by a person who was considering job offers in two different
Southern California cities. He wanted to know the frequency
at which the air pollution index in each city reached un-
healthy values. Since the two cities used different indices,
rio comparison was possible, and rio information could be
given to assist him in making the decision.
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3. Index Reporting Systems
The air pollution index can provide a mechanism for
reporting air quality data to the public. Most of the
agencies which do not use indices, as defined here,
nevertheless report their actual pollutant concentrations
in daily newspapers, or in weekly or monthly agency
publications. Although extensive information on this subject
is not available, the materials provided by the agencies
indicate there is great variety in the ways in which air
quality data are reported and the media used. Some agencies
list the concentrations of all pollutants; some list just
several. Some list the air quality standards alongside the
data; some do not. It is probable that a uniform reporting
format could be established for reporting air quality data,
as one recent paper has suggested. ’ Before this is done,
it would be useful to survey in greater detail the ways in
which agencies now report their air quality data to the public.
A research project focusing on different air quality reporting
formats, with emphasis on the public’s acceptance and corn—
prehension of these formats, would be most useful for this
purpose.
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4. Monitoring Siting
One of the most common air monitoring problems ——
the selection of suitable air monitoring sities —— also
surfaces when air pollution indices are considered.
Several respondents in this survey strongly emphasized
this problem. When data are generated at several air
monitoring locations in an urban area, which location or
locations should be used for computing the index? Because
of the complexity of this problem, and the variations in
air monitoring networks, insufficient data was obtained to
provide insight into the ways in which agencies currently
solve this problem.
However, there was some evidence that many air pollution
agencies, faced with the problem of deciding which air
monitoring site to use in computing their index, selected the
station having the “maximum” concentrations. Others,
arbitrarily chose a “downtown” location, irrespective of its
concentration levels; still others obtained an average of
several locations. Because of the importance of this problem,
and the complex issues it raises, it is recommended that an
extensive survey be conducted of site locations, the basis
for choosing different sites, and the way in which choice of
site affects index values.
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5. Follow-up Study
The approach used to gather much of the information
in this study —- solicitation of information by telephone -—
proved itself to be a powerful means for inexpensively
gathering large quantities of data on a national scale.
The data permit drawing a comprehensive picture of national
practices regarding air pollution indices, but the present
study does not probe deeply into monitoring and data
reporting practices in each metropolitan area. For a more
in—depth analysis of these factors, written questionnaires
could be used, or on—site interviews conducted with air
pollution control agency personnel. It is recommended, in
future follow—up studies, that these more intensive survey
methods be considered,
If a standardized air pollution index were proposed
by the Federal Government, it would be desirable to survey
attitudes of the technical staffs of U.S. air pOllutj n
agencies toward this new index. Such a follow—up survey
could provide valuable insights into whether the index is
formulated properly; it would also give an indication of
the ljkl±hood that air pollution control agencies will
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successfully adopt the index. The follow—up survey could
be accomplished through a carefully designed, written
questionnaire accompanied by a description of the index.
The written questionnaire could be followed by personal
interviews at selected air pollution agencies, particularly
those agencies expressing unclear or ambiguous feelings
about the index. The goal of the follow—up survey should
be to determine any unsatisfactory characteristics of the
proposed index, changes necessary to correct these problems,
and obstacles which may impede adoption of a standardized
index. The follow—up survey also should examine the
response of air pollution control agency personnel toward
any standardized monitoring procedures designed to improve
the quality of data for the index.
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REFERENCES
1. “Environmental Quality—1973 —- The Fourth Annual
Report of the Council on Environmental Quality,”
Washington, D.C., 1973.
2. “Planning for Environmental Indices,” Report of the
Planning Committee on Environmental Indices to the
Environmental Studies Board, National Research Council,
National Academy of Sciences, Preliminary Final Report,
September 30, 1974.
3. “The National Environmental Indices: Air Quality and
Outdoor Recreation,” MTR—6l59, The Mitre Corporation,
McLean, Va., 1972.
4. “Environmental Quality-1972 —- The Third Annual Report
of the Council onEnvironmental Quality,” Washington,
D.C., August 1972.
5. Public Law 88—206, as amended by Public Law 91—604,
84 Stat. 1676 (42 u.s.c. 1857 et. seq.).
6. “National Primary and Secondary Ambient Air Quality
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1971, pp. 8186—8201.
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9. Shenfeld, L., “Note on Ontario’s Air Pollution Index
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11. Babcock, L.R., “A Combined Pollution Index for
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National Laboratory, Oak Ridge, Tenn., September 1971.
13. Miller, T.L, “Short Time Averaging Relationships to
Air Quality Standards (SPARAQS) -— A Predictive Air
Quality Index Model for Use by Air Pollution Control
Agencies,” Paper #73—351, Presented at the 66th Annual
Meeting of the Air Pollution Control Association,
June 1973.
14. Rich, T.A., “Air Pollution Studies Aided by Overall
Air Pollution Index,” Env. Sci. and Tech. , 1, 7-96
(1967).
15. Fensterstock, J.C., K. Goodman, G.M. Duggan, and
W.S. Baker, “The Development and Utilization of an
Air Quality Index,” Paper #69—73, Presented at the
62nd Annual Meeting of the Air Pollution Control
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16. Bisselle, C.A., “Strategic Environmental Assessment
System: Air and Water Pollution Indicators,”
MTR—6565, The Mitre Corporation, McLean, Va.,
April 1974.
17. “National Environmental Policy Act of 1969 -— Environ-
mental Indices —— Status of Development Pursuant to
Sections 102(2) (B) and 204 of the Act,” Committee on
Interior and Insular Affairs, United States Senate,
December 1973.
18. “Indicators of Environmental Quality,” W.A. Thomas,
Ed., Plenum, New York, N.Y., 1972.
19. “1973—1974 Directory of Governmental Air Pollution
Agencies,” Air Pollution Control Association,
Pittsburgh, Pa., 1973.
97
-------
20. Cullen, J.J., T.V. Flaherty, Jr., and S.M. Barnett,
“Indices for Dissemination of Ambient Air Quality
Information to the Public,” Paper #74—221, Presented
at the 67th Annual Meeting of the Air Pollution
Control Association, June 1974.
21. Reidy, N., and C. Dziewulskj, “Homogeneous Dis-
semination of Ambient Air Quality Levels to the
News Media and the Public or the Need to Eschew
Obfuscation,” Paper #73—352, Presen€èd at the
66th Annual Meeting of the Air Pollution Control
Association, June 1973.
22. “Ohio—West Virginia Air Compact Is Approved,”
Env. Sci. and Tech. , , 182 (1970).
23. Hunt, W.F., W.M. Cox, W.R. Ott, and G. Thom,
“A Common Air Quality Reporting Format: Precursor
to an Air Quality Index,” Presented at the Fifth
Annual Environmental Engineering and Science
Conference, Louisville, Ky., March 1975.
98
-------
APPENDIX A
AIR POLLUTION INDEX DATA SHEET
I. Agency
Agency Name: ___________________
Address: ________________________
Telephone Number: ____________________
Number of Staff (Total): _______________
II. Does the Agency use an Air Pollution Index?
Yes ____ No ____
If yes , what is it called? __________________
Length of years in use: _________________
Purpose of Index: ________________________
If no , why? ________________
III. If yes , what parameters are covered in the Index?
a. Equation for calculating Index: _____________
b. Method of converting averaging times to Index
values (i.e., factors): ___________________
c. Range of values for Index:
99
-------
d. Method of interpreting, e.g., air quality
categories, Index for stated uses:
e.
f.
g. Can any literature or write—up on the index
be provided? Yes ___ No ____
h. What are the advantages and disadvantages of
using this Index?
IV. Additional Comments:
Frequency
period to
which Index is reported and time
which it applies:
Number and selection the monitoring
which provide data for Index:
sites
100
-------
APPENDIX B
I = 2(0) ÷ (NO 2 ) + (CO) + lO(COH)
The index was based on the “Combined Air Pollution Index” previously developed by the
San Francisco Bay Area Air Pollution Control District (BAAE’CD). It was computed from monitoring
date at the control station at 1845 East Roosevelt Street, Phoenix. The index was found to be
inconsistent with the public’s “perceived” impression of air pollution levels. That is, the
mountains surrounding Phoenix would often be barely visible during the winter months and yet the
index would ret ister in the light air pollution range. This inconsistency produced much controversy
by the public and news media regarding the validity of the index. After one year of increasing
problems with this combined index, it was discontinued. (The early BAAPCD index, on which this index
was modeled, also was discontinued in San Francisco for essentially the same reasons.)
A number of other air pollution indices also were evaluated using the Phoenix air monitoring
data (ORAQI, M.U.R.C., etc.). In all cases, problems were encountered due to inconstencies of
each index with perceived visibility reduction.
LENA TA OF TIME IN USE
Initiated 7/1/70
Discontinued in 1971
L UC A H IA S
Phoenix, Arizona
P HOSE
J i l l
INDEX ANALYSIS RECORD
Maricopa County Health Department
Environmental Services Division
Bureau of Air Pollution Control
1825 East Roosevelt
hoenix, Arizona 85006
0— 25
26— 50
51— 75
7 6—100
>100
Clean Air
Light Air Pollution
Moderate Air pollution
Heavy Air Pollution
Severe Air Pollution
0—100+
FLU AT Is S
MONIEORINO INFORMMTICN REPOPPINA FREQAFNCH
2 full continuous air monitoring stations with 7 additional
stations measuring CO, and in most cases, Oj, CON, TSP; 11 A.M. Daily
all 9 stations are attached to a minicomputer.
.101
-------
INDEX ANALYSIS RECORD
LOCATION AO l 500
Anaheim, California Orange County Air Pollution Control District
811 N. Broadway Street
PHONE Santa Ana, California 92701
(714)834—5370
A00 5co S I l L
24
L 1 o o/ccunty
VAPIA ALPS
so
CATEGORIES
EPISODE CRITERIA:
CD, ppm S02t ppm Oxidant, ppm
(1—hr.) (12—hr.) (1—hr.) (24—hr.) (1—hr.)
40 20 0.5 0.2 0.2 Stage 1
75 35 1.0 0.7 0.4 Stage 2
100* 50 2.0 0.9 0.6* Stage 3
*Concentrat ion to last for one—hour and predicted to persist
for one additional hour
Actual Concentrations
EOOATION
N/A
OP NO RIP A ION
The previoos system in use for approximately 2 years was based on the Smog Alert system pre-
viously operated in Los Angeles for 20 years. The old Los Angeles system was based on instantaneous
concentration maxima. It was intended to advise school children and other sensitive persons to
curtail strenuous activities with the onset of moderately high air pollution levels (See Los Angeles
Index Analysis Record). The new episode aystem was initiated in April 1974 to comply with require-
ments of the California State Air Resources Soard. It is identical to the Los Angeles episode
system, except that the Los Angeles system also includes instantaneous maxima in its episode criteria.
MOSIT
S
6
OMING INFORMATION
continuous air monitoring
different source—receptor
stations covering
zones
TAPs_TINs EREQOENC’E
Reported only
stated levels
exceeded.
when
are
I LEAICTA a
April
places
in use
E TIME IN ONE Adopted
10, 1974. Re—
previous syster
for 2 years
-------
INDEX ANALYSIS RECORD
LOCAtION AGENCY
Los Angeles, California Los Angeles County Air Pollution Control District
PHONE 434 S. San Pedro Street
(213)974—7411 Los Angeles, California 90013
AGENCY SIZE VAP IAOCPN
380
EI I1 N il 2
,EOORIEs
EPISODE CRITERIA:
00, ppm SO2 ppm Oxidant, ppm
(1—hr.) (12—hr.) (1—hr.) (24—hr.) (1—hr.)
40 20 0.5 0.2 0.2 Stage 1
75 45 1.0 0.7 0.4 Stage 2
100* 50 2.0 0.9 0.6* Stage 3
*Concentration to last for one—hour and predicted to persist
for one additional hour ___________________
:RIPTIOM
The episode criteria also include the following instantaneous maxima:
CO, ppm NOx ppm 5021 ppm 031 ppm
Stege 1: 50 3 3 .50
Stage 2: 100 5 5 1.0
Stage 3: 150 10 10 1.5
Previouely, the Agency operated a “Smog Alert” system for 20 years which incorporated the above
instantaneous maxima. The Agency also operated a “School and Health Smog Warning System” since
July 2, 1969, which was intended to give protection from moderate air pollution levels to school
students and persons with respiratory or cardiac disorders. Under this system, a “School Smog
Warning” was issued for the sir monitoring zone affected whenever the ozone forecast level exceeds
0.35 ppm (instantaneous) in any zone. The warning was issued to the mass media as part of the
daily air pollution forecast for broadcast to the public and for the city and county superintendents
of schools throughout the area.
In June 1971, this health advisory system was expanded to include CO (40 ppm, instantaneous)
and NO (1.5 ppm, instantaneous). The purpose of the system was to enable students to curtail
strenuous activities with the onset of moderately high air pollution levels and to warn persons
having cardiac, respiratory diseases, or other air pollution eensetivities so that they may take
precautions to protect themselves. On March 28, 1974, a new system, the “Emergency Contingency
Plan (Regulation VII)” was adopted; it incorporated the part of the instantaneous criteria of the
old system but added new levels for 1—hour and 24—hour averaging times. The new Stage 1 Episode
replaces the function of School and Health Smog Warning health advisory. Including the new, lower
levels for the 1—hour averaging times in the system has increased the number of times for which
health advisories (Stage 1 Episodes) for ozone are reached. In the 6—month period between April 1
and September 30, there were 83 days with Stage 1 Episodes —— one—fourth of the year —— and no days
having Stage 2 or Stage 3 episodes.
Actual Concentrations
P QO A P ION
N/A
50 51t55iN5 INFOSMATION J•EPONTIN5 FREQOENCY LCNGTEE or tiss is uscAdopted
Continuous monitoring network covering 13 “air Reported only when March 28, 1975. Re—
monitoring zones” in Los Angeles County L stated levels are previous syster
1 exceeded operating for 20 ve xi
103
-------
INDEX ANALYSIS RECORD
i
Sari Francisco, California
—
(415) 771—6000
iC [ • i C
Say Area Air Pollution Control District
939 Ellis Street
San Francisco, California 94109
acidant,
0.0—.05
.06—.09
.l0—.15
. 16—.25
>.25
>.60
ppm
CU, ppm
0— 5
6—10
11—15
16—20
> 20
>100
flAk Ni S ri
flu . .
[ F R
CCI 1 11110
i i ACCIF •C A t iO,i
40. C
2
NO 2 , ppm
0.0—0.1
. ll—.l4
.lS—.20
.21—.30
> .30
>1.6
Coil units
0.0—.05
0.6—1.5
1.6—2.5
2.6—3.5
>3.5
> 10
Air Pollution
Clean Air
Light
Significant
Heavy
Severe
Emercency
Actual
Concentrations
1 su i s s
N/A
iESC PiRTisN
Data and categories are reported aeparately for each of 11 air monitoring stations. Categories
are based on the highest value attained prior to 4:00 P.M. each day. Categories are Specified for
al l, four pollutants, and the maximum category becomes the cverall designation for the air monitoring
station. “For example: If San Jose shows an oxidant of 0.07 parts per million (light air pollution),
and a coefficient of haze of 2.7 (heavy air pollution), the designation for San Jose will be heavy air
pollution,” [ Air Currents , Vol. 15, No. 4, April 1972, p. 3.
The current systom, which was adoptod in April 1972, emphasizes the maximum values; in 1968,
however, the Agency began operating a Combined Pollutant Index (CPI( with five descriptor categories:
This index was computed separately for three geographical argas —— north, central, and south. This
combined index was replaced by the current one because it sometimes led to public confusion. Combining
the four pollutants often created ambiguity —— at the Livermore station, for example, the federal
oxidant standard might be violated for 106 days in a given year accompanied by low values for the other
air Pollutants; the resulting index would appear low, however. Conversely, high values sometimes were
observed at the San Francisco station even though no standard was violated, giving misleading values.
CPI = 2W ) + (M0 2 ( + (CU) ± 10 (COH(
x
0— 25
26— 50
51— 75
76—100
> 101
Clean Air
Licht Air Pollution
Moderate Air Pollution
Heavy Air Pollution
Severe Air Pollution
M5SiTORINC. IIAFOF,M5TiQN i5 OflnINs ‘ EQ5EN(jy I Lr, 5y Ask 154
jForecast at 9:30 A.M. Begun in
11 full continuous air monitoring stations values at (Replaced
4:30 P.M. ( 1972
104
U P4 ASk
Oct. 1968
in April
-------
INDEX ANALYSIS RECORD
LOCATION
AGENCY
Denver, Colorado
State of Colorado Department of Health
4210 East 11th Avenue
Denver, Colorado 60220
AROSE
(303)388—6111
AGENCY SIZE
YA SIASLES
CLASSIFICATION
D YAY
10 SIY PARTI( ELATE
fl PART, SCATTER
01 A
54
Lii GI l 2 [ ] [ ] COIN
VIYIR ILITT
2BC
2
CATEGORIES
PARSE
,
Assigned Color
CO . ppm COB Number Code Descriptor
1—5+
EQUATION
<10 <1.0 1 Green Good
N/A
10—19 1.0—1.9 2 yellow Good
20—29 2.0—2.9 3 Blue Fair
:0—39 3.0—3.9 4 Orange Fair
4 0+ 4.0+ 5 Red Poor
The Denver Air Quality Index (DAQI) consists of two separate parts: an air quality index
forecast end an air pollution dispersal index. The air quality index forecast is issued for the
pollutant which has the highest assigned number. This number is determined by comparing the
hourly average concentration for each pollutant with trend data for the same time period (monthly
plots of the four—year average pollutant concentration for each hour of the day). Based on the
comparison, an index forecast is made for the next three—hour period. The index may be updated
hourly if aignificant changes are predicted.
The air pollution dispersal index is issued each morning and covers four time periods: A.t4.
today, P.M. today, A.M. tomorrow, and P.M. tomorrow. ma index is the product of the wind speed
(meters/second) and the mixing depth (hundreds of meters). The index categories and respective
values are:
Bad 0/100 to 19/100
Lair 20/100 to 39/100
Good 40/100 to 59/100
Excellent 60/100 to 100/100
The air pollution index forecast is issued both as a number and a color; the number is
displayed on a downtown bank sign, and, the number and color are displayed on a local freeway
sign. The air pollution dispersal index is released to the local news media.
OAITORINO INFORMATION REPORTING PREOAENCT S.ENGTA OF TIME III USE
Monitoring data for index comes from one downtown station Hourly as required 2 1/2 Years
(Adopted July 1972)
105
-------
INDEX ANALYSIS RECORD
LO0AT IC .
Department of Environmental Protection
Connecticut
Air Compliance Section
165 Capitol Avenue
(203)566—40 :0 Hartford, Connectirut ooii:
A l
10 5
v A IfteLF$ C
fl , C AC
3D 1 C
LI II1 C
CA IcCOPIES
031 ppm
0.000—0.04 Good
0.041—0.09 Satisfactory
0.091—0.20 Unsatisfactory
0.201..0.40 Unhealthy
0.401+ Hormful
IJ O C
Actual Concentrations
C T !QN
N/A
DE N Im ’ I II N
The index report gave the previous day’s maxi mum one—hour ozone concentration and a forecast
for the expected afternoon category. Before it was diaconti;iued, a summer ozone index was reported
in four cities listed in Table 5. Each daily index report gave the previous day’s maximum one—hour
ozone concentration and category, and the projected maximum one—hour ozone category for the afternoon.
On Friday a similar report was issued with the projected maximum one—hour ozone category fcr Saturday.
A similar type index was planned but not started for 902 and CCH. The Acency is presently considerina
the adoption of a new index.
MONITO CNC JMFO M*tIOC4
—
one continuous telemetered stations in each of the
four
R&PO!’ING FmtQU!NC,
10:30 A.M. Daily,
tP1GTH Sr 1lI1( IN Njfl
cities.
3 P.M. Friday
6 Months
Discontinued
in 1973
-------
INDEX ANALYSIS RECORD
LOCATION -
Jacksonvillo, Florida
P A IONE
(904)633—3303
HE SC Al PT 0 N
Department of Health. Welfare. & Bio—Environmontal Services
Bio—Environmental Services Division
Air and Water Pollution Control
515 West 6th Street
Jacksonville, Florida 32202
pAw-u-Il u.n FL I A lit SI ni rE 0
Actual Concentrations
CL A S Al F IC AT 014
6C 3 C
EQUATION
C
I A;A. 1O0
1 1 S
C. concentration of pollutant i
1
S = air quality standard for
pollutant I
Pollutant
Co 9.0 ppm
So 2
COH
NO 2
TSP
8
The concentration of each of six air pollutants is reported as a function of the percent of the
federal air quality standard; the average of these values also is reported. Thus, for each day, A 1
is reported, along with I. The air quality standards used in the calculation are as follows:
Averaging
_________ j Time (hrs. )
0.14 ppm 24
3.0 units* 8
0,20 ppm* 24
260 ISg/m 3 24
Because concentrations observed at different stations are not the same, the station whose
daily concentrations are highest is selected for use in computing the index.
Ozone 0.08 ppm
‘Unofficial Standard
1
V ARIA AL IS
iI I1
None
MONITORING INFORMATION IREPORTING FREQUENCH I LENGTH OF TIME IN USE
2 full continuous monitoring stations; 1 continuous I Daily, Including
oxidant station; 12 sequential stations which measure Sunday 2 1/2 Years
SO 2 , 802, arid TSP
107
-------
INDEX ANALYSIS RECORD
LOCATION
Miami, Florida
H GE IC Y
Metropolitan Dade County Pollution Control
864 N.H. 23rd Street
Miami, Florida 33127
EQUATION
I = A.
A. = subindex obtained as
described below.
air quality index is computed from five subindices. Each subindex is obtained by assigning
values for particular ranges of pollutant concentrations. Individual desciptora also are
each of the subindices:
CD , ppm NO 2 , ppm Oxidant, ppm
CON, units Descriptor Subindex, A.
_________________ 1 .
0—
1..
1
2
D —.o 0 5
.005—.Ol
0 . 0 5
. 005—.01
0—O . s
0.5 ..l
Light
2
2—
4
.Dl— ,02
.Dl—.04
Light
4
4—
6
.02 -. 06
.04—.06
1—2
Normal
8
6— 8
8—35
. 06—.lO
.lO—.2 0
• 0 6_ . Dg
.0 9_ j o
2—3
3—4
Moderate
Neavy
12
**
7—15
7—15
4— 6
2- 4
1— 2
0— 1
Visibility, miles
(No smoke or haze)
(Little haze or smoke)
(Smoke or haze)
(Smoke or haze)
(Smoke or haze)
(Smoke or haze)
Descriptor
Good
Good
Poor
Bad
Very Bad
Severe
Subindex, A.
1
2
4
8
12
**
**
tt when values occur in these ranges, the staff is required to notify the “Chief of
to “continue to make hourly analyses of specific pollutants until concentrations
again for two hours.” Values assigned by Chief of Evaluation are 12.
Evaluation” and
are ‘normal’
MONITOR 1 MG IN POMMA lION
Index i calCulated from concentrations at one air
monitoring stat ion only (864 N.w. 23rd Street, Miami).
REPORTING EREOHERCY LENSTIP O F TIME IN USE
Daily (weekdays only). 2 1/2 Years
Calculated at 9 A. !’ !.
PHONE
(305) 635—7524
0— 20
20— 40
40— 60
60— 80
80—100
Good
Normal
Moderate
Heavy
Severe
HA PIG C
0—100+
The
subindex
given to
108
-------
INDEX ANALYSIS RECORD
Tampa, Florida
PHONF
81 ) 223—1311
16
/county
0—19
20—39
40—49
00—79
80—99
100-4-
. NCV
1.37
[ 5.7 (C./s.)l
1 ii
L J
The Agency uses the Oak Ridge Air Quality Index (ORAQI) described in Chapter VI,Section 2,
except that CO is not being measured at the present time, but this appears to be temporary. The
average concentration for each variable is calculated for the 24—hour period running from 8 A.M.
to 8 A.M. each day. Each pollutant is weighted in the index according to its toxicological effect
on humans, as indicated by the ORAQI nomograms.
Hillsborough County Environmental Protection Commission
305 North Morgan Street
Stovall Professional Building — Sixth Floor
Tampa, Florida 33602
V fl t A B C FS
NIH’
LI II1
Light
Moderate
Heavy
Very Heavy
Extremely Heavy
Acute
RANGE
0—100+
EQUATION
MOplI ORING BRORMAtION 1BEP0RTIN4 FBIOuENCY I LENGrA OF THE IN SE
Index is based on data from 2 continuOus air monitoring I I
8 A.M. Daily 3 Years
stations.
109
-------
INDEX ANALYSIS RECORD
IJESCEPAT JON
F C U AT I S A
The Air Pollution Index (API) is calculated as the averac,e of the sum of three pollutant
concentration:standard ratios using the criteria shown below. The average is then multiplied by
100 to give an index value of 100 when all pollutants are equal to their respective criteria. Thus,
at index values above 100 “adverse effects could begin to be felt” while cleaner air would be indicateFi
by lower values.
Averac inc
Time (hrs. )
Pollutant
Suspended Particulate
Matter [ PM] 24
[ so 2 ]
[ co]
l97G
Federal Criteria
150 c/M
315 /M 3
24
24 17 rr/M
Although, the agency does not define any descriptor catecories for the index v 5lues, the two
television stations which use the index have developed a common system of categories and descriptors
for display purposes.
MONITORING
INFORMATION
NERO
TYING FREQUENCY
LENGTH OH TIME IN
Index
concentrations obtained from one “representative” 3
P.M.
Daily
5 Years
station.
(Initiated
in 1970)
O C H 0 0 0
Atlanta, Georgia
P NO A F
Fulton County Health Department
99 Butler Street, S.F.
Atlanta, Georgia 30303
None
0—1004
API
(i ii [ so 2 ] [ co]’\
3 150 315 17 )
110
-------
INDEX ANALYSIS RECORD
Weighting factors K are
determined as indicated below.
Weighting factors for use in the equation are as follows:
Pollutant
1
2
3
4
5
4
4
8
4
4
K!
1
3.07
267
267
533
16.7
Thus, the index is calculated as: I = 3.07(CO) + 267(N0 2 ) + 267(502) + 533(03) + 16.7(COH)
The weighting factors K relate primarily to short—term primery (health effect) standards.
Descriptor categories are defined as follows:
Good: “All pollutant levels are below the numerical value
for the annual standards.”
Acceptable: “One or nore of the pollutants are above the annual
standard, but yet at a level such that the standard
can be met unless the level persists for an extended
period of time.”
Unsatisfactory: “One or more of the pollutants is at a level such
that if the level persists, the annual standard
will not be met.”
Unhealthy:
“One or more of the pollutants is at such a level
that health effects may occur after prolonged
exposure. One or more of the pollutants may be
exceeding short—term standards. One or more of
the pollutants may have reached or nay be approaching
the ‘Alert’ level specified in the Episode Control
Regulation.”
The current index was adopted in October 1972. It replaced an earlier index initiated in 1970 which
contained only two pollutants — — SO 2 and COH —— and which used the same computation procedure but
with slightly different weighting factors.
Example of Report:
“Afternoon Pollutant Index: 77: Problem Pollutant:
Ozone; Primary Source: Vehicular Exhaust; The ozone
levels were elevated during the afternoon, but did
not remain below the unhealthy level.”
LOLA ION
Louisville, Kentucky
(502) 635—7471
Air Pollution Control District of Jefferson county
400 Reynolds Building
2500 South Third Street
Louisville, Kentucky 40208
0—30
31—CO
6 1—90
90+
Good
Acceptable
Unsatisfactory
Unhealthy
0—90+
EQU A TIGN
5
I CC .
1.1
i=l
Averaging
_________ iThits Time (hrs. )
CO ppm
NO 2 ppm
502 ppm
Ozone ppm
CON units
MONITO!IMQ ‘dVo AArIoN I .r o .ti’ o EQU€NCY LUACTA OF TIME IN USE
Not Available
9:00 A.M. and ‘Initiated Oct. 1972
3:00 P.M. Daily replacing an index
started in 1970
1 11
-------
INDEX ANALYSIS RECORD
LOCATION
Daltimore, Maryland
AGENCY
Maryland State Department of Health and Mental Hygiene
Bureau of Air Quality Control
610 H. Howard Street
Baltimore, Maryland 21202
PWONE
(301)383—2042
bi lE
(T*TL
g o
Pill
v ,p iA e t. P s
NO, PAKTICUI.ATC PART. SCATTER
N IiJ 0 (01 1 V(S iflILItY
CLASSiFICAT ION
CATCGORIE(
0— 24 Good
25— 49 Fair
50— 74 Poor
75— 99 Very Poor
100—249 Hazardous
250—749 Dangerous
750—999 Emergency
1000+ Endangerment
RANO
0—1000+
F QU L T I O .
N/A
PSCRiPTiOU
The Maryland Elevated Pollutant Index used in Baltimore County is very similar to the index used
in the Washington, D.C. region. The Maryland Index is calculated using the following table which is
based on the NAAQS and Federal Episode Criteria:
Index Breakpoints
Maryland co 302 008 ND 2 O x
Standard K oom — _ _ _
More Adverse 25 20 0.10 1.75 0.25 0.04
Serious 50 35 0.20 3.00 0.40 0.08
Alert 100 60 0.70 5.50 0.60 0.10
Warning 250 90 1.40 9.20 1.2 0.40
Emergency 750 110 1.85 12.8 1.6 0.60
Endangerment l0D0 125 2.33 14.6 2.0 0.70
The 1—hour averages (where standard do not exist) are based on correlation
analysis relating the concentrations for the NAAQS averaging time to the
concentrations at a 1—hour averaging time.
For each of the five pollutants, the above breakpoints (K and its corresponding concentration)
are coordinates of a segmented linear function intercepting the origin, as discussed in Chapter VI,
Section 2. Each of the five curves gives a pollutant subindex; the maximum subindex is reported as
the daily index for Baltimore County.
.lOH(TORING INFOEMAT(ON
REPOPTIPIG FREQUEIICY
LENS?
N SF TINE
Not
Available
9:15 A.M. and
USE
2:15 P.M.
2
Years
112
-------
INDEX ANALYSIS RECORD
0 — 30
31 — 00
61 — 90
91 — 120
121 and over
Extremely light contamination
Light contamination
Medium contamination
Heavy contamination
Extremely heavy contamination
M.U.R.C. — pronouncad “murk” — is an acronym which maans Measure of Undesirable Respirable
Contaminants. The M.U.]LC. index values reflect an approximation of the actual concentration of
suspended particulate matter in the air. A range of M.U.R.C. values from 30 to 120 by the above
equation equals a CUH rance of 0.3 to 2.15. This range is approximately equal to 35 to 350
microcrams/cubic meter. However, for M.U.R.C. values higher than 120, the correlation with suspended
particulate matter concentration does not hold.
The morning report includes the index for Detroit tooether with the previous day’s 24—hour
averace, maximum, and minimum values. These values are transmitted by telephone to the major news-
papers and Mational Weather Service teletype. The afternoon report includes the Detroit index and,
on a rotating basis, an index from one of the 13 monitoring stations. These values are transmitted
to the Mational Weather Service and one television station.
The M.U.R.C. index io also used in Memphis, Tennessee.
Loc.:o T IsN -
Detroit, Michigan
Wayne County Department of Health
Air Pollution Control Division
1311 East Jefferson
Detroit, Michigan 48207
M.U.R.C. Index
Decree of Dii tiness
DEATRIFI lOPE
EQUATION
0 —121 - F
M.U.R.C. = 70(C0M) 0 7
MONITORING INFORMATION MEPQPTIMN FREQUENCY LENORN SF RIMQ IN 55€
13 station telemetered network 8 A.M. and 4 P.M. 7 Years
113
-------
INDEX ANALYSIS RECOPC
LOCATION
Minnesota
AA ,NCT
Minnesota Pollution Control Agency
Division of Air Quality
1935 W. County Road, 52
Roseville M Innesota 55113
Y AC h T
(612) 296—7.373
I TSI T
fl CITY
SITE
37
1ARl&OLT S F _A SEIFICASION
1 (1 ES IT : VASTlY Li-SEC COAT S b! FEC 3
3
Cu 2 fl II fl IC , ,! 5151 TiLl ] S
C ATE 60 0 1ES —
APEX 3021 ppb CO , ppm PM, ng/m 3
0— 20 0— 20 0—3 0— 60 Good
21:300 21:100 4—9 61:150 Satisfactory
1C 1 155 101 140 10+ 151 260 Unsatisfactory
1554- 141+ 10+ 261+ Unhealthy
F IANCE
0-155÷
r uori Aw
, l. 7
( S0 C CPM\
APEX + 9 ±
The Minnesota Air Pollution Index (APEX) operates in the four Cities shown in Chapter V
(Table 5). For each city, APEX is calculated using the city—wide average concentrations for each
pollutant (if more than one monitoring station exists) for the 24—hour period ending at 2 P.M.
The APEX equation is identical to the Oak Ridge Air Quality Index, with a coefficient of 9.58.
This coefficient was chosen to give APEX a value of 100 when the cunCentraticna of all three
pollutants are equal to their secondary NAAQS. The following terms are included in the e:;uation:
C 50 : The 24—hour average concentration of 302 in ppb; this value
2 is divided by the secondary NAAQS 24—hour standard of 100 ppb
(Note: this is the 1971 standard).
C : The maximum eight—hour average concentration of CD in ppm;
CO this value is divided by the secondary RAAQS eight—hour
standard of 9 ppm.
g ; The 24—hour concentration of total suspended particulate matter in
PM in ugmm 3 ; this value ie divided by the secondary NAAQS 24—hour
standard of 150 ug/m I.
In addition to reporting the calculated APEX value, the actual Concentrations for each pollutant
are reported. These values are reported on ‘Air Quality clucks,” which are divided into categories
based on the primary and secondary NAAQS;
Actual Ccncentraticns
S I ‘11111SF 0 1 . 1 1 , 0 1 5 ‘C1111 FSl— ILW , ’ , V
L II A I Sb , lA O ’ TA -h o. I A ’Il 1 ’
P A I S I ‘-F ‘ ‘ l O t u S FACTS I ’ l l I S iS ’ ITIAI TC I I II A I ‘ 1 511511 h O’ I ’
S , 1 Fl C’S ’S 5, 0 11 I 5 I s I I , , 1, S o , , , IL —
\ 0,, i i 7
5 1 . 1 . 1 1 , , .iJ C, C.
LTNGTA C F TIME IN USL
3 Years
APEX
MO ISTen ING 1NFONMITI O I, I P npe.TINC OP EQSPNCT
Minneapolis—St. Paul —— three continuous rsonituring station
Duluth —— one monitoring station 4 P.14. Daily
Rochester —— one monitoring station
114
-------
INDEX ANALYSIS RECORD
0— 60
60—260
260—365
365+
0— 60
60—150
150— 260
260 +
0— 40
40—130
130—160
160+
DESCRIPTION
The New Jersey Air Quality Index operates in the 20 cities listed in Chapter V (Table 5).
The index reports actual concentrations “rather than arbitrary index numbers.” For the 24—hour
period ending at 2 P.M. daily, the Index reports the maximum 1—hour average concentration for CO
and 03 and the 24—hour average for SO 2 and COH. These units and time periods were chosen so the
Index levels could be compared with the NAAQS for each pollutant. The index for each pollutant is
displayed on an “Air Quality Clock” with the appropriate category divisions as shown below:
HOW THE NEW JERSEY AIR QUALITY INDEX RELATES TO NATIONAL AIR QUALITY STANDARDS
CARBON M4R4114t
1-hr. MavimuIS
IiiiiiyrvaIn per Cucic Meter
5114014 1 5
1-hr. Marleule
MicrogramS per Cubic Meter
SU L F UR 0151241
24 -hr. Average
Microgram , per Cubrc Meter
-
.‘
‘
Primary B
Secordary
Standard
1-hr. Ma,iete
a,,
- ,
Prie,ry B
Secondary
Staadard
1-hr. MaciTeM
‘ Secondary
adad
24-hr. Average
t’J—Pr he .ry
Staedard
24—hr. Average
tiecr BAG PAtT ICLES
24-hr. Borraqe
Microgrems nor Coblc rrerer
sccrodru
Borual Boerage
24-hr. doerage
Clock faces show national primary and secondary air quality standards for sulfur dioxide, smoke and
particles, cerbon monoxide, and oxidants, as well as verbal ratings for pollutant levels to be used
in the New Jersey Air Quality Index proposed by the Bureau of Air Pollution Control.
The Index falls in the “Unhealthful” category when the primary HAAQS for the pollutant has been
exceeded at any time during the 24—hour period. The other categories are determined on the basis of
the secondary NAAQS (for 50 and CON), mathematically (for co), or empirically (for 03), based on
studies cited in the Federa Air Quality Criteria documents. The “Good”, “satisfactory”, and
“Unsatisfactory” categories are reached as the contaminant levels become increasingly higher but are
still under the primary NAAQS.
In addition to the four individual indices, an overall daily rating is given for each city.
This rating is a one—word summar based on the highest rating reached by any pollutant on that day.
MONITORING INFOMMATION
- - eceseTiNG EREQUENCT LENGTH S E TIME IN Ott
18 c?ntinuous telemetered monitoring stations, four
Continuous comprehensive monitoring laboratories, 2 P.M. Daily Adopted May 15, 1972
covering 20 sities in all.
LOCH r Is N
New Jersey
New Jersey Bureau of Air Pollution Control
Division of Environmental Quality
Department of Environmental Protection
P. 0. Box 1390
‘°“ New Jersey 08625
0— 3
3—15
15—40
40+
¶ “HonE
CO, 2%/rn 3 SO 2 , COB o , ug/m 3 Actual Concentrations
_____________ EQUATION
Good
Satisfactory N/A
Unsatisfactory
Unhealthful
115
-------
INDEX ANALYSIS RECORD
New York
PTOSE
(518)457—7456
C AT! GT E PEE
237
CU, ppm
SD 2 , ppm
CON
0.0— 4.9
0.0 —0.02
0.0—0 .
5.0—15.0
0.03—0.08
0.4—0.7
>15.0
>0.08
New York State Department of Environmental Conservation
50 Wolf Road
Albany, New York 12201
Index Rat inc Actual Concentrations
r C C I
Low N/A
Ned iom
High
The New York State Index operates in the 11 localities shown in Chapter V (Table 5). Index
ratin s are calrulated daily for each location:
Morning Index Rating ; based on the 24—hoor average pollutant concentrations
period ending at midnight.
Noon Index Rating : based on the 24—hour averages for the period ending
at noon.
Forecast Index Rating : hased en the Morning and Noon Index Ratings, the
Index Forecast Rating is iasued at 3 P.M. for the
24—hour period beginning at midnight.
Afternoon Index Rating: based on the 24—hoor averages for the period ending
at 2 P.M.
The Index Rating categories are based on the New York State Ambient Air Quality Standards:
Low : concentrations in the lower half of standards
Medium; concentrations in the upper half of standards
Nigh : concentrations exceed standards
LOAGI OF TIME IN USE
5 Years
jj nitiated in late l9
MONIF5RINC INFUSMATION REPORTING ENEGIPENCT
11 State—wide continuous telematered monitoring stations 3 P.M. Daily
I)
116
-------
INDEX ANALYSIS RECORD
Neei York, New York
(212) 506—591
c r LOG PIES
Co.. ppm SO 2 , ppm
(8—hr.) (24—hr.)
— o—o.u: 0—0.5
— 0.04—0.06 0.5—1.0
— 0.67—0.10 1.1—1.6
>9.0 >0.10 >1.6
Department of Air Resources
Environmental Protection Administration
City of New York
51 Astor Place
New York.. New ‘iork 10013
CON 5 NO 2 , ppm Ox, ppm
— (24—hr.) (1—hr.)
0—6.0 5
0.06—0.09
0 • 10—0.12
>0.12
N/A
Valucs for winter catecOrieS, summer values are 0.1 CON less
SE SC P IPT ION
The Overall Air Quality Index is the one—word descriptor for the highest severity category
reached by any one of the five pollutants.
MONITORING INEORMATION
REPORTING FREQUENCY
LENGTH
OF TIME IN LINE
11
continuous
monitoring stations
Daily
4
Years
¶ RANGE
>0.08
Actual Concentrations
EOAATION
Good
Acceptable
Unsatisfactory
Unhealthy
117
-------
INDEX ANALYSIS RECORD
The Ohio Air Quality Index is used in 13 cities within the State (Chapter V, Table S) Ths
index is calculated using the following table, which is based on the NA.AQS and Federal Episode Criteria:
Index Breakpoints
Averag ing Time
(hrs.)
Ohio Air Quality
Standard
W5 rn i ng
K CO 502 Pt4 SO 2 xPM NO 2 NO 2 Ox
— i sL i sz* ( Iag/M J i sz& &iaLE zk
N/A 6 24 24 24 24 1 1
100 10 260 150
— — — 119
200 17 800 375 65,000 282 1,130 2u0
300 34 1,600 625 261,000 565 2,260 800
400 46 2,100 875 393,000 750 3,000 1,200
For each of five pollutants, the above breakpoints (1K and its corresponding concentration) are
the coordinates of a segmented linear function intercepting the origin, as discussed in Chapter vi,
Section 2. Each of the five curves gives a pollutant subindex; the maximum subindex is reported
as the daily index.
MONITO INs INFORMA’IOM
Variea from city to city
JArPO .TINc rqtgucpcy
Variea from city
to city
LENGTH OP TIME IN UI!
2 Years
j
Ohio
Ohio Environmental Protection Aganc
361 East Broad Street
Columbus, Ohio 4 2l0
0— 40
41— 60
01— BO
81— 99
100
101—125
Excellent
very Good
Oood
Fair
Clean Air Std.
Unsatisfactory
126—150
151—175
176—199
200
30 C)
400
Poor
Very Poor
Extremely Poor
Alert
Warning
Emergency
0—4CCi +
N/A
Alert
Emerr’ency
.L18
-------
INDEX ANALYSIS RECORD
LOCATION
Oklahoma City, Oklahoma
PHONE
(405)427—8651
ASINCY
Oklahoma City County Health Department
.
Air Quality Control Section
921 HE 23rd Street
Oklahoma City Oklahoma 73105
EI II !
A ol NI V TIlL
VARIABLES
JJIL ‘ LI I LIVILTIL III All EAI 1 T SIASTLA
LIJ 511 I A le
CLASSIFICHTIOY
1A 1 C
CATEGO RIE S
.
M.U.R.C. Index Degree of Dirtiness
C — IC Extremely liqht contamination
3 1 — 60 Licht contamination
61 - 9D Medium contamination
91 - 120 Heavy contamination
121 and over Extremely heavy contamination
RANGE
0—125+
F GIL & I ION
0 7
M.U.R.C. = 7D(COH)
VA N I N L ET Il l N
M.U.R.C. — pronounced “murk” — is an acronym which means Measure of Undesirable Respirable
Cuntaminants. The M.U.R.C. index values reflect an approximation of the actual concentration of
suspended particulate matter in the air. A range of M.U.R.C. values frum 30 to 120 by the above
equation ec uals a COH ranse of 0.3 to 2.15. This ran&-e is approximately equal to 35 to 350
micrograms/cubic meter. However, for M.U.R.C. values hicher than 120 the correlation with suspended
particulate matter concentration does net hnld.
The M.U.R.C. index is currently used in Detroit, Michicran, and Memphis, Tennessee.
MONITORING INFANMATION REPORTING FREQUENCY LENGTH OF TIME IAN UNE
Not Available A.M. and P.M. 2 1/2 Years
Discontinued in 1973
119
-------
INDEX ANALYSIS RECORD
LOCATION [ AGENCY
Oregon State Department of Environmental Quality
Portland, Oregon Air Quality Control Division
PAYNE 1234 S.W. Morrison
(503)229—5348 Portland, Oregon 97205
AGENCY SIZE
STATE: *
CI I 5 20
GAPIA S C Y E
NC,
ElI, 1) 1
A YE CON I L S
Percent
0—100%
ECUATIAN
0— 20
Very Light
21— 40
Light
N/A
41— 70
Normal
71— 90
Heavy
91—100
Very Heavy
,E SC NIPTIGN
The Agency’s index, a “Pollution Particle Index,” represents the relative percent of
particulates in the air as measured by an instrument called the nephelometer. A normal day is
considered to have a reference level of 50 based en 1973 data; B—scattering used to compute the
index is based on the frequency distribution curve for 1973 data. The maximum 1—hour average
value observed prior to 4:00 P.M. each day is used in computing the index. Fog or light rain do
not affect the nephelometer, “which is specific for airborne particulate.”
Gaseous air contaminants are listed separately as maximum one—hour average values, along
with reference data explaining the concentrations.
*
State Agency operates city air pollution control agency; estimate of staff includes portion of
Agency manpower involved in immediate metropolitan area.
MONITORING INFORMATION NNPOIIRA FREONEREP LEMCPP OF T’MF IN USA —
Index is based on one nephelometer site; other stations Once Daily at 4 P.M. 1/2 Year
exist but do not have a nephelomater. (Initiated in
August 1974)
120
-------
INDEX ANALYSIS RECORD
LOCATION
Philadelphia, Pennsylvania
.C,,NCV
City of Philadelphia
Department of Public Health
Air Management Services
4320 Wissahickon Avenue
Philadelphia,__Pennsylvania 19129
(2l5)686—784U
flA n
EI I1 CII ?
‘ CI N ’ C SI l l.
94
VARIABLES C LASS IE ICATIOSI
I I I SIC PA5TlCtIt.AT I PART. SCATTE.A
2BC
L IIIJ SSI (Oil fl VISIRILITV
ATEGORIES
1 — Below Average
4 — 6 Average
7 — 10 Above Average
RANGE
1-10
EOUATION
1(50 ) + I(C0H)
2 2
The air pollution information issued each day is based on the sulfur dioxide (SO ) concentration
and the smoke shade measured at 1501 E. Lycoming Street, the Air Management Services ?.aboratory. This
station was chosen for its length of time as a continuous data producer. The forecast is issued twice
daily and is based on the above mentioned pollutants measured during the early morning and mid—day
hours, indicative of average conditions for the day. The forecast can be affected by changes in wind
speed, wind direction, atmospheric inversions, and other weather parameters, as well as increased or
reduced pollutant loading by industrial, automotive, and other community sources.
Both the forecast and index are based on frequency distributions of sulfur dioxide and smoke
shade. The morning forecast is prepared by comparing the $02 concentration for the 10th hour of any
day with a frequency distribution of past data broken down into class intervals which have been
assigned values of 1 through 10. The same procedure is done to the 2—4 A.M. smoke shade level and
a corresponding number of 1 to 10 assigned to it. The average of these two numbers is issued to the
news media and others as the “Air Pollution Forecast” for the day. The actual index for the pre-
ceding day is computed by comparing the 24—hour averages of both SO 2 and smoke shade with frequency
distributions of past data based on daily averages of these pollutants. Thus, the actual index for
the previous day is given to the media at the same time a forecast is made. Both the forecast and
index are related in that 1, 2, and 3 are considered low levels of Pollution; 4, 5, and 6 are average
levels; 7, B, and 9 above average levels; and 10 is considered an adverse level. The 12th hour $02
concentration and the 6—8 A.M. smoke shade level are used to predict the afternoon forecast.
MONITORING INFORMATION NEPORTINA FNEOAENCT LENATR OF TIM5 IN A lt
13 stations, 1 mobile van 11 A.M. and 4 P.M. 10 Years
121
-------
INDEX ANALYSIS RECORD
EQ UAT ION
.
Pittsburqh, Pennsylvania
.
‘‘
Allegheny County Health Department
.
Bureau of Air Pollution Control
101 39th street
Pittsburch, Pennsylvania 15201
EH UN U
[ 412)681—9600
fl U
02
U
fl flioNUiri 11011 [ 1 lUll l
L1 iIII ElI II
2C U B
UA IE U.TOlFl
U_ 15 Excellent
15 35 satisfactory
35—100 Unsatiefactery
100—200 Peer — First Stare Alcrt
200—250 Very Poor — second Stagu Alert
250 -F Emergency — Emermency stage
EANQI
0—250+
EQUATION
I
( [ S0 I
API ;O E 373
\
The Air Pollution Index (API) equation includes:
[ so 2 ]: the 24—hour average SO 2 concentration (ppm)
0.14: the 24—hour Primary NAAQS for s o2 (ppm)
[ CON]: the 24—hour average coefficient of haze
1.73: the CON value equivalent to the Primary NAAQS of 260 ug/rs for
particulate matter; in Allegheny County 1 CON 150 ug/m 3
Although the onset of air pollution episodes is not based on API, the index can be correlated
with the Allegheny County Episode Criteria. These criteria include the critical values of 503 and
COO (or their product) coupled with at least 30 hours of air stagnation. Index values of 100, 200,
and 250 approximately correspond to the Alert I, Alert II , and Emergency Episode stages.
API is reported seven days a week to the public and news media through separate telephone
recordings [ Codophone). The report includes the average index for the whole county, the index
value at each monitoring location, and the average index for the previous 365 days.
usElTemAs INEONMATI5N PFPOPT:NN ENEQUENC U LENOT II 5F TIME T I USE
6:30 and 10:30 A.N.
Seven continuous monitorinc stations 5:30 and 10:30 P.14. 4 Years
(Initiated in 1971)
122
-------
INDEX ANALYSIS RECORD
Chatanooc s, Tennessee
P OCT C
(6ls)eu7—4321
E l
C A OP SCRIP N
0— 70
75—130
130—200
>200
22
uq/m 3
3
uy/m
3
pc/rn
3
pc/rn
Licjht
Mode rate
Heavy
Alert
Chatanooya—Hamilton County Air Pollution Control Bureau
3511 Rossville Ooulevard
Chatanooc’a, Tennessee 37407
This Agancy 1 s index reflects only particulate matter (as measured by high volume samplers).
Sometimes another pollutant is also reported with the index if it exceeds a standard.
LOCATION
L I I
Actual Concentration
N/A
EIONITORIN5 INFCRM*715N PEPORTINO •REQUENCY LPN000 CU lIM p IN USE
Index based on two hi—vol samplers at roof of main
location. One runs S A.M. — S A.M.; the other Twice Daily i 1/2 Years
runs 4 P.M. — 4 P.M.
123
-------
INDEX ANALYSIS RECORD
OCAT ;ON
Memphis, Tennessee
,cF ACY
City of Memphis - Shelby Health Department
814 Jefferson Avenue
Memphis, Tennessee 38105
“°“
(901)522—2736
STATE
A
ACA S ?F
14
VA . ;aBLrS
LIII . ii PnWlI( EAT; [ II] nir CACTI
Iii1 (OIl 11111 CITE IV
CLASSIF
IA 1 C
CATECORIES
M.U.R.C. Index Degree of Dirtiness
0— 0 Extremely light contamination
31- 60 Light contamination
61— 90 Medium contamination
91—120 Heavy contamination
PA S C C
0—120- 1-
S Au A r 0 N
M.U.R.C. 7o(cou) 07
This single—pollutant index, based on two—hour average COH readings, is the same as the M.EU.R.C.
index used in Oklahoma City, Ok1ahoma and Detroit Michigan. The Memphis M.U.R.C. is based on two—
hour average COH readings. The M.U.R.C. index values reflect an approximation of the actual con-
centration of suspended particulate matter. Index values from 30 to 120 equals a range of 0.3 to
2.15 COH. This range is approximately equal to 35 to 350 micrograms/cubic meter. For M.U.R.C.
values higher than 120, this correlation does not hold.
MONITORING INFORMAtION REPORTING FREQUENCY LENGTH OF TIME III USE
12 monitoring sites covering gases and particulate Daily, weekdays only 2 Years
Index is based on one site that is centrally located in 10 A.M. and 4 P.M.
the urban area.
124
-------
INDEX ANALYSIS RECORD
GOCATIOG
Nashville, Tennessee
A l SI U
Metropolitan Health Department of Nashville and Davidson County
Bureao of Environmental Control
Pollution Control Division
311 23rd Avenue, North
Nashville, Tennessee 37203
PASSE
(615)327—9312
AGE NIT SITE
UIAI C
Ic r ) 17
VE SIAPLES
[ 11cc) [ 1 1 1 5 1 ). PUATI II IIATE [ j PAST. SCUTTLE
CLASSIFICATION
1
C 1 C
CATE GORIES
0—25 slight
26—50 Moderate
51—75 Heavy
>75 Extremely Heavy
RANGE
0—75+
PQUATION
I = 25(COH)
DESCRIPTION
The “Air Pollution Index ” is based only on the soiling index (CON) and has four categories.
Nigh—volume samplers measure particulate levels at 18 sites, but the index uses only the CON
data from tape samplers operate at two sites. The index is computed from data for the 2—hour
period from 6:00 A.M. — 8:00 A.M. Due to staffing limitations, the index is only estimated for
Saturday and Sunday.
IREPOPTINA FREQUENCY LENGTO OF TIME IN USE
MONITORING INFORMATION
2 full continuous air monitorina stations (502, NOx , I Daily, including Sat. f 5 Years
Qr, COH); other measurements at 20 sites. Index is based and Sunday, at 8 A.M.I (Initiated Jan. 1970)
on CON only which is measured at two sites. I I -
125
-------
INDEX ANALYSIS RECORD
LOCA ICU
Dallas, Texas
p NONE
2l4) 630—1111
DE SC RJ P T ON
City of Dallas Department of PubUc Health
Air Pollution Control Section
1500 W. Mockincsbird Street
Dallas, Texas 75235
[ QUA nON
2(TSP) + NO 2
1= 10
(24—hour averages)
The formula results from a 6—month research study which was undertaken to determine how
concentrations observed at two locations 5 miles apart —— the air pollution laboratory and down$ wn
Dallas —— relate to each other. The study indicated that downtown particulate levels generally
were two times those at the la1oratory location, while NO 2 levels were approximately the same at
both locations. Using these results, downtown levels could be estimated from measurements at the
laboratory, and this fact was incorporated into the index. Thus, in computing the index, TSP and
NO 2 are 24—hour average concentrations measured at the laboratory (ug/rn 3 ), while the index reflects
the downtown levels.
The index is released at ll;00 A.M. Monday through Friday along with a 24—hour forecast. The
forecast is based cn index level trends, projected meteorological conditions, and anticipated air
pollution activities. The Friday forecast attempts to cover the weekend.
For index values greater than 66, the possibility exists for declaring the “Alert Level” for
an air pollution episode, as defined by the Texas Air Pollution Control Board. The index value
approaching 100 indicates that pollution levels are becoming high enough that, if they continue,
a ‘h arning Level” may be declared.
0—30 Light
31—60 Moderate
61—90 Heavy
>91 Severe
0—91+
MO 4PYQRINQ INFORMA’ ON IREOOPIIPIQ FREQUENCY I LENGTH OF TIME IN US C
Index is computed from one monitoring site equipped with Once Daily at
high—volume sampler and NO 2 instrument. 11 A.M. J 2 1/2 Years
I I(initiated AUg. l97
126
-------
INDEX ANALYSIS RECORD
The Puget Sound Air Quality Index is calculated using the following table, which is based on
the stages of an Emergency Episode Plan:
Index Breakpoints
SO 2 , ppm COB SO, )c COB
1< ( 24—hr.) ( 24—hr. )
Alert 50 0.3 3.0 0.2
Warning 100 0.6 5.0 0.8
Emergency 150 0.8 7.0 1.2
For each of the three pollutants, the above breakpoints (1< and its corresponding concentration)
are the coordinates of a segmented linear function intercepting the origin, as discussed in
Chapter VI, Section 2. Each of the three curves gives a pollutant subindex; the maximum subindex is
reported as the daily index.
Seattle, Washington
PHONE
(206) 344—7328
Puget Sound Air Pollution Control Agency
410 West Harrison Street
Seattle, Wsshington 98119
0— 50 Alert u r
50-100 Warning N/A
100—150 Emergency
0—150+
MONITO IMG IMFORUATIOW REPOPTING FREQUENCY LENGTH HF TIME N USE
10 air monitoring sites with data telernetered to a 3 times daily:
central computer morning, afternoon, 4 Years
and evening (Initiated in 1971)
127
-------
INDEX ANALYSIS RECORD
314 TI l l 1
5 lF ;i jnrItor1 D.C.
(2 02)347—4€i7
LJi
I E cr ’ , ITTION
14
EFIL
District of Columbia Department of Environmental Servicoo
Bureau of Air and Water Pollution Control
014 N Streot, N.W.
Washington, D.C. 20001
0— 24 Coo S
25— 49 Fair
50— 74 Poor
75— 99 Dnhealthy
100—249 hazardous
250—749 Dangerous
7504 Very Daneoroos
This index, which is operated by the Washington Metropolitan Council of Governments (COG) for
the six jurisdictions in the Washington metropolitan area (Chapter V, Table 5), is ver\ similar
to the index used in Baltimore, Maryland, from which it was partially derived. The COG Index is
calcoisted osino the followinc ta ole, which is based on the NAAQS and Federal Episode Criteria:
Index Breakpoints
(1—hour averace concentrations)
K
CO 302 CON NO 2 O x
E2 £E —
Secondary NAAQS 25 2D 0.10 1.75 0.2 5 0.04
Primary NAAQS 50 35 0.20 3.00 0.40 0.08
Alert IG O 60 0.70 5.D 0.60 D.10
Warning 250 9t 1.40 9.20 1.2 0.40
Emergency 750 110 1.85 12.8 1.6 0 :60
The 1—hour criteria (where standards do not exist) are based on correlation
analyses relating the concentrations at the NAAQS averaging time to the
concentrations at a 1—hour avereqinc time.
For each of the five pollutants, the above breakpoints (K and its corresponding concentration) are
coordinates of a segmented linear function intercepting the origin, as discussed in Chapter VI,
Section 2. Each of the five curves gives a pollutant subindex; the maximum subindex is reported as
the daily index for the region.
The index is made available twice daily to the news media through a telephone recording.
E QU A ‘10 ‘ 1
N/A
0—750+
MONITOHIMU IMFUTMATIUN RATOETINU T AEOJTNCY LENGTH OF TIMUING AT
One station in each of the six jurisdictions 9 A.M. and 3 P.M. 1 1/2 Years
Daily
128
-------
INDEX ANALYSIS RECORD
LOCATION
Alberta, Canada
AGENCV Department of the Environment
Environmental Protection Services
Division of Pollution Control
Mimer Buildinc, 10040 — 104 Street
Edmonton, Alberta T5J 0Z6
P NONE
(403)427—5893
1 ’”
AGE NC V SIZE
26
vA N I NeLES
10 AT I II I.AT I; eMIT ICATTER
N 2 eoit
CLNSSIFICATION
SA,C
)
CATF GORIES
0— 25 Clean
26— 50 Light
Moderate
100+ Severe
RANGE
0—100+
EQUATION
ox 3 ’ 3 + (0.5 NO or NO 2 ) + CO 05
+ (10 COH) 1 ’ 2 + fso 2 \ 1 55
The Alberta Air Quality Index operates in the two cities shown in Chapter V 1 Table 6. As its
author notes, “the intent of the Alberta index is to make the public aware of the general air quality.
They should not associate a specific index level with a health hazard as the index was not designed to
serve that purpose. [ Our combined index 1 has the advantage of a single index number representing the
five major pollutants but has the disadvantage of being unable to determine from the index value
whether a specific pollutant is high or low. However, as the index is for information only and the
Alberta alert plan will cover the situation of high individual pollutant levels, this is deemed to
be an acceptable weakness.”
The index is based on pollutant levels from a single monitoring station within each city. The
index equation is designed so each pollutant contributes a value of 15 to the combined index at the
following 1—hour air quality standards:
1—tour standard
Co 13 ppm
So 2 17 pphm
Particulate Matter 0.9 CON
NOx 30 pphm
NO 15 pphm
Oxldants 8 pphm
The resulting index equation is very sensitive to smoke levels (particulate matter) and
oxidants, thereby reflecting the public concern with visibility and health effects. The index cate-
gories are based on those used in San Francisco prior to October 1968. Monthly mean and peak index
values for Edmonton and Calgary are calculated and compared to meteorological and emission inventory
data.
IIONITO•IMG INVOIMATION flPOPT ING •REOUCNGV LINOTH OF TIME IN Ufl
8 A.14. and 3 P.M. 1 Year
One station in each city Daily
129
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INDEX ANALYSIS RECORD
0—lOOt
API = 0.2 (30.5 CON -1- 126.0
Lst : rio, Canada Air Management Branch
— _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Ministry of the Environment
‘ NO NE — 680 Bay Street
(41G)9 05—6 43 Toronto, Ontario M5S 158
L I
70
L I
C ATESORICS
0—31 Acceptable
32—49 Advisory Level
50—74 First Alert
75—99 Second Alert
100+ Episode Threshold Level
DEAN RIPRI5N
The Ontario Air Pollution Index (API) operates in six cities of the Province (Chapter V, Table 6).
Tho data required to calculate the index are:
CON = 24—hour running average of the soiling index expressed as coefficient
of haze per thousand linear feet.
so 2 24—hour running average of sulfur dioxide concentrations in parts
per million.
The coefficients and exponent of the API equation were derived by evaluating the concentration
data for sulfur dioxide and suspended particulate matter from past air pollution episodes. An analysis
of the data revealed the following pairs of values could be used as the threshold to a severe episode
at which the Air eollution Index is set to equal 100:
1. Suspended particulates 600 ugJm which for Toronto is equivalent to 2.75 CON
and sulphur dioxide .13 p.p.m.
2. Suspended particulates 500 ug/m 3 equivalent to 2.24 CON and sulphur dioxide
.25 p.p.m.
Setting the equation for the Air Pollution Index as a function of the 24—hour average concentra
tions of and CON as follows:
API = A(COH) + 5(502) (1)
and substituting the foregoing given pairs of values for avercge concentrations of CON and $02 at API
equal to 100, gives the following equation:
API’ = 30.5(C0H + 126.0(502) (2)
For a desirable scale the API was made to be an exponential function of API’, that is,
API = C [ API’J° (3)
API = C [ 30.5(CoN) + 126,0(502)30 (4)
The levels of coefficient of haze and sulfur dioxide set by Ontario Regulations as objectives
are 24—hour averages of CON at 1.0 and $02 at .10 p.p.m. Setting API = 32 at these levels provides
a range of indices twice as greet, that is, from 33 to 100, for control action to take place than for
the range of acceptable levels, 0 to 32. Substituting API = 100 for levels of CON and 502 given above
and API = 32 when CON = 1.0 and $02 = .10 equation (4) can be solved for C and 0 to give the equation
for the Air Pollution Index for Toronto as follows:
API = .2 [ 30.5(CON) + 126.0(S0 2 )] 1.35
(Continued)
LI N
M5RITOPINS INFORMATION REPORT,Ns FRF5UCNCY LLN5IPI OF TIME IN U SC
Several continuous telemetered monitoring stations Daily 5 Years
130
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INDEX ANALYSIS RECORD
Ontario. Canada (Cont’d)
PH ON F
A NIP
An Air Pollution index of less than 32 is considered acceptable. At these levels, concentrations
of sulfur dioxide and particulates should have little or no effect on human health. At the advisory
Level at which the Air Pollution Index is equal to 32 and meteorolocical conditions are expected to
remain adverse for at least six more hours, owners of significant sources of pollution in the community
may be advised to make preparation for the curtailment of their operations.
The First Alert occurs when the Air Pollution Index reaches 50 and adverse weather is forecast to
continue for at least six hours. The Minister may order major sources to curtail their activities.
Studies have shown that at levels over 50, patients with chronic respiratory diseases may experience
an accentuation in symptoms.
If the abatement action does not succeed in lowering the pollution levels and the Index rises
to 75, the Second Alert is issued. The Minister may order sources to make further curtailment in
Operations. When the Index reaches 1(j0, the Pdr Pollution Episode Threshold LeveL the Minister
may re uire the curtailment of all sources not essential to public health or safety. At this level,
the air pollution could have mild effects on healthy people and might seriously endanger those with
severe cardiac or respiratory disease.
EQUATION
MONITORING UF00001ION REPORTING FREQUENCY LENGTH OL lIAR IN USE —
131
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES USING INDICES
AGENCY NO. 1 AGENCY SIZE: 24 INDEX TYPE: 1D 1 B
We previously used the 4—stage alert system that
was developed by the Los Angeles Air Pollution Control
District 20 years ago. This was. supplemented by a
health advisory system designed to advise the most
sensitive portion of the population. Now we are adopting
an alert system that is based on the EPA federal episode
warning system. We find that our community has become
accustomed to the old 4—stage alert system, which was
based on ozone, and the process of re—educating the
public has been very difficult. They find the new
episode warning system levels confusing, and the re-
education process is a tremendous job. The news media,
for example, still want to use the old terminology,
which is inconsistent with the new episode terminology.
The introduction, right now, of “an index would bury
us.”
AGENCY NO. 2 AGENCY SIZE: 380 INDEX TYPE: 3D 1 B
Previously, we used a health advisory system
designed to warn school children and persons with
respiratory illness and cardiac problems. We
recently adopted a new episode system which has new
levels for the various air pollutants and includes
the old health advisory warning level as its Stage 1
Episode. With the new lower levels, there are more
health advisory warnings (Stage 1 Episodes) than
before. This created some public confusion initially.
One of our problems is to get notification of adverse
air pollution levels to the public, particularly to
the schools, as quickly as possible. We are con-
sidering a new scheme in which a radio transmitter
would transmit notification of an episode to radio
receivers at each school.
* NOTE THESE ARE INTERPRETATIONS Y THE INVESTIGATORS OF VIEWS EXPRESSED 9’? RESPONOENTS OURING
TELEPHONE CONVERSATIONS.
132
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APPENDIX C. INFURED COMMENTS FROM RESPONDENTS *
AGENCIES USING INDICES (Cont’d )
AGENCY NO. 3 AGENCY SIZE: 220 INDEX TYPE: 4D 2 8
Eight years ago we began using a combined air
pollution index, which lumped CO , SO , and 03 into
one number. We found the use of suc an index to
be confusing to the pi.iblic, and we abandoned it for
a new approach in 1972. At one station, where CO
and particulates were high while the other pollutants
were low, we obtained misleadingly high index values.
Conversely, at another station where the federal
oxidant standard was exceeded frequently, while other
pollutants were low, the net result was a misleadingly
low index value. The combined index tended more to
confuse the public than to clarify or communicate.
We therefore abandoned the combined approach after
four years and adopted a less misleading approach in
which the highest concentrations determine the
descriptor category reported for each air monitoring
station.
AGENCY NO. 4 AGENCY SIZE: 54 INDEX TYPE: 2B 2 C
The index we use originated in 1972 when a
businessman offered to erect a sign on his building
to give daily air quality readings. Response to
this display sign has been so good that similar
signs “should be placed all over the city.” Our
agency also prepares an air quality index forecast
for use on a 24—hour telephone recording loop.
AGENCY NO. 5 AGENCY SIZE: 15 INDEX TYPE: 6C 3 C
Our daily air pollution index has proved quite
satisfactory. It covers six pollutants —— TSP, COH,
CC, NO 2 , SO 2 , and 03. The newspapers carry it daily,
including Sunday, but most people probably don’t see
it.
NOTE THESE ARE INTERPRETATIONS BY THE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURING
TELEPHONE CONVERSATIONS.
133
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES USING INDICES (cont’d )
AGENCY NO. 6 AGENCY SIZE: 50 INDEX TYPE: 5C 3 C
Our “pollution index,” which has been in use for
about 3 years, appears to be accepted well by the public.
It is a combined index with 5 variables —— NO 2 , CO , O3
COH, and visibility factor. One problem with the index
has to do with its lack of’ representativeness, Some—
times considerable pollution, such as heavy smoke,
occurs in one part of the city, but, because we do not
monitor there, our index does not reflect these levels.
Thus our index does not adequately reflect the spatial
variation in pollutant concentration. There is, perhaps,
no way to make a perfect, all—purpose index.
AGENCY NO. 7 AGENCY SIZE: 14 INDEX TYPE: 3C 3 C
Established to maintain good public relations,
the index has generated much interest. It is
relayed to several radio and television stations
and the Weather Bureau for dissemination to the
public.
AGENCY NO. 8 AGENCY SIZE: 16 INDEX TYPE: 5A 3 A
We recently have begun using a “total air quality
index” that is based on ORAQI. In general, we don’t
have much trouble explaining this index —— we provide
a public information bulletin on the subject.
NOTE TNESE ARE INTERPRETATIONS BY TNE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURING
TELEPHONE CONVERSATIONS.
134
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES USING INDICES (Cont’d )
AGENCY NO. 9 AGENCY SIZE: 39 INDEX TYPE: 5C 3 B
Our air pollution index has great public interest,
and it is reported by TV, the radio, and the newspaper.
Our monitoring data are not as spatially representative
as we would like them to, but that is a general problem
with monitoring networks.
AGENCY NO. 10 AGENCY SIZE; 77 INDEX TYPE: 1A 1 C
The public can relate to this index more
easily than to concentrations, since the scale is
comparable to the Fahrenheit temperature scale.
AGENCY NO. 11 AGENCY SIZE: 13 INDEX TYPE: 3A 3 3
Once the public became familiar with the index,
it proved useful. It now appears that people keep
track of the change in the air quality category
from day to day. However, the numbers resulting
from the index calculation are not necessarily
meaningful.
AGENCY NO. 12 AGENCY SIZE: 44 INDEX TYPE: 3D 1 A
In general, air quality indices are meaningless
because they do not accurately reflect air quality.
The data from which they are calculated is not
representative of the region where the index is
applicable.
AGENCY NO. 13 AGENCY SIZE: 37 INDEX TYPE: 3D 1 A
Indices are helpful to the public, since they
allow the public to get a feeling about air quality.
However, the layman does not understand the technical
language of air pollutiOn. Some people have asked
us about the air quality of other cities before
moving their home.
* NOTE: THESE ARE INTERPRETATIONS BY THE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURING
TELEPHONE CONVERSATIONS.
135
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES USING INDICES (cont’d )
AGENCY NO. 14 AGENCY SIZE: 382 INDEX TYPE: 5D 2 A
Although indices do not tell the whole story
about air pollution levels, they are useful in
keeping the public aware of air quality. The many
different indices in use make it difficult to
compare them. Our index was not developed on any
scientific basis and is not intended as such.
AGENCY NO. 15 AGENCY SIZE: 12 INDEX TYPE: 3D 1 A
Our index must not be that important to
people because we have received no comments on it
since it was established.
AGENCY NO. 16 AGENCY SIZE: 65 INDEX TYPE: 5B 2 B
We have received a good response to our index,
which is reported on the local radio and television
stations and in the newspapers. The index helps
inform the public about air quality and pollutant—
source relationships.
AGENCY NO. 17 AGENCY SIZE: 80 INDEX TYPE: 5B 2 B
Although initial public response to the index
has been very good, people have become insensitive
to it since the index exceeds 100 (the standard)
most of the time. I question the validity of
reporting only the index for the “dirtiest” part
of the city, and I question representativeness
for the region as a whole.
AGENCY NO. 18 AGENCY SIZE: 20 INDEX TYPE: 1D 1 C
Our index, a pollution particle index, was started
just three weeks ago. It is based on measurements from
the integrating nephelometer, which reflects the amount
of light scattering from small particles, independent
of humidity. We report the index once a day.
THESE ARE INTERPRETATIONS BY THE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURING
TELEPHONE CONVERSATIONS.
136
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES USING INDICES (cont’g
AGENCY NO. 19 AGENCY SIZE: 82 INDEX TYPE: 2C 3 B
We think our index is one of the best. It
reports not only the major pollutants in both a
separate and combined index, but the index values
also are related to the air pollution episode program.
AGENCY NO. 20 AGENCY SIZE: 94 INDEX TYPE: 2B 3 C
Indices cannot describe the complete picture
of the air quality and are useful only for indicating
short-term and not the long-term air quality.
AGENCY NO. 21 AGENCY SIZE: 22 INDEX TYPE: 1D 1 C
Our index seems to work adequately. It gives
people a feeling or a sense of how bad air pollution
is on a daily basis. In the index, particulate matter
alone (measured by the high-volume sampler) is reported;
however, if ozone turns out to be high, we report that
separately, as when we experience an air pollution
alert
AGENCY NO, 22 AGENCY SIZE 14 INDEX TYPE: 1A 1 C
Our index reports COH only, patterned after the
index used in Detroit. We have discussed our index
with the other air pollution control agencies, and
we feel there is no one best index. Our index,
which is usually published along with the weather
report, seems to correlate well with public perception.
AGENCY NO. 23 AGENCY S4ZE: 17 INDEX TYPE: 1c 1 C
Although we measure all six of the major air
pollutants, we just report CC I I in our index, with
the CCII values multiplied by 25. We also report the
pollen count for three monitoring stations.
* NOTE: THESE ARE INTERPRETATIONS BY THE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURING
TELEPHONE CONVERSATIONS.
137
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES USING INDICES (cont’d )
AGENCY NO. 24 AGENCY SIZE: 21 INDEX TYPE: 2C 3 B
We based our index on a six—month research study
in which we correlated the concentrations measured at
a nearby location with those measured downtown. We
found downtown particulate concentrations to be two
times those at the reference location while NO con-
centrations were approximately the same at bot places.
Now we predict the downtown values using only data
from this reference location, Our combined index
relates particulate and NO concentrations to the
Texas “alert” and hlwarning* episode levels. The index
appears very accurate and is quite useful for the
purpose for which it was intended.
AGENCY NO. 25 AGENCY SIZE: 39 INDEX TYPE: 2B 2 B
Our index was begun in 1971; before that we
reported actual numerical measurements, The newspapers,
however, wanted something more simple. Our index,
which is based on SO 2 and particulate concentrations,
really answered the need. We have had many favorable
comments, with a generally favorable response from
the public.
AGENCY NO. 26 AGENCY SIZE: 237 INDEX TYPE: 3D 1 A
In general, the public is not technically
capable of interpreting the index values. Further-
more, combining several pollutant concentrations
into one index number does not accurately reflect
air quality. As a result, our index reports actual
pollutant concentrations with a “low,” “medium,”
and “high” classification scheme which relates the
pollutant concentration to its standard.
AGENCY NO. 27 AGENCY SIZE: <10 INDEX TYPE: 3A 3 B
This index is not good for much besides public
information. It generally has been accepted well
by the public, and the television stations and
newspapers report the index daily. The idea of a
uniform national index is appealing, but such an
index should not be complex (i.e., OR QI), since
smaller agencies would have difficulty handling it.
*NOTE: TNESE ARE INTERPRETATIONS BY THE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURING
TELEPHONE CONVERSATIONS.
138
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES USING INDICES (cont’d )
AGENCY NO. 28 AGENCY SIZE: 37 INDEX TYPE: 3A 3 B
Our index was initiated to give the public a
better idea about the quality of the air. It is
calculated by weighting each pollutant concentration
differently and then computing the average of the
resulting values. The weighting of each pollutant
concentration is very resonable in that the values
obtained give a low—to-high, good-to-bad scale.
However, we have reservations about the averaging
operation, because it tends to mask higher pollutant
concentrations. Regarding a uniform national index,
some cities may not like the idea, because it will
“compare” them to other cities, or they may just
want to have their own index.
AGENCY NO. 29 AGENCY SIZE: 228 INDEX TYPE: 5B 2 B
Our index has received a favorable response
from the public. It was developed by our state
agency for use in 12 local air pollution control
agencies. Now, our greatest need is for stand-
ardized guidelines for the location of monitoring
stations.
NOTE: THESE ARE INTERPRETATIONS BY THE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURING
TELEPHONE CONVERSATIONS.
139
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES NOT USING INDICES
AGENCY NO. 30 AGENCY SIZE: 25
We previously had an index, the Oak Ridge Air
Quality Index (ORAQI), which we used for a couple of
years. We tried to correlate the index with visibility
but found it didn’t work. The poor relationship between
observed visibility and index values created public
confusion, and we had many complaints. We feel that
some form of index is needed, however, but it should
be one that has meaning to the public —— not one that
produces contradictions between index values and
perceived pollution levels.
AGENCY NO. 31 AGENCY SIZE: 26
Our agency reports the actual air pollutant
concentrations —— carbon monoxide, oxidant, nitrogen
dioxide, particulates. These concentrations, along
with forecast values for the following day are reported
by the newspaper along with the weather summary. A
combined index would require us to add the gases and
particulates, which does not seem reasonable. We have
found it possible to educate the public about the
mearl .ing of these four pollutants, and a combined index
does not seem necessary.
AGENCY NO. 32 AGENCY SIZE: 53
For our public, use of an air pollution index
probably would be confusing. We would rather educate
the public to understand the scientific units (i.e.,
parts per million, micrograms per cubic meter).
Although this education process is difficult, we
believe that our public is just beginning to understand.
In a given city, the decision on whether or not to use
an index probably depends on the public involved. This
decision probably varies from city to city; any approach
is all right so long as the public understands it. In
our area, photochemical oxidant is the largest problem,
so we report these concentrations, along with a 30—hour
oxidant forecast.
‘NOTE: THESE ARE INTERPRETATIONS BY THE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURING
TELEPHONE CONVERSATIONS.
140
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES NOT USING INDICES (Cont’d )
AGENCY NO. 33 AGENCY SIZE: 53
Our agency does not use an index. The concept of
an air pollution index probably is a good one, but
there are not enough studies yet to provide a solid
basis for such an index. If our agency adopts an air
pollution index, we probably will develop one ourselves.
With the telemetered data now available from our
monitoring stations, an index for our agency might be
a aood idea.
AGENCY NO. 34 AGENCY SIZE: 11
We considered adopting an air pollution index for
our air pollution control agency, and the Oak Ridge
Air Quality Index (ORAQI) was proposed. Our air pol-
lution control board turned it down, however, because
we didn’t have enough staff to compile the index.
AGENCY SIZE: 35 AGENCY SIZE: 21
We have only a very limited air monitoring network.
It provides only one 24—hour high—volume sampler reading
at each of two sites per week. Therefore, we do not
now have enough monitoring data to implement a daily
air pollution index.
AGENCY NO. 36 AGENCY SIZE: 175
In general, indices leave much open to inter-
pretation. The air quality categories used in many
indices don’t tell the exact story.
AGENCY NO. 37 AGENCY SIZE: 18
We feel that the index we are currently
formulating for adoption in early 1975 will give a
better representation of environmental conditions
to the public than is possible at present.
* NOTE: THESE ARE INTERPRETATIONS BY THE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURING
TELEPHONE CONVERSATIONS.
141
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES NOT USING INDICES (Cont’d )
AGENCY NO. 38 AGENCY SIZE: 87
Although it was suggested several years ago
that the two newspapers begin reporting air pollution
levels, such reporting began only recently. Now
using the daily pollutant concentrations supplied
by our agency, one newspaper reports concentrations
as a percentage of federal standards, while the other
reports the actual concentrations along with the
corresponding federal standard. Because the per-
centage scheme appears more acceptable, we may
begin reporting our data to the newspapers in
this manner in the future.
AGENCY NO. 39 AGENCY SIZE: 15
We do not now use an air pollution index, but we
have looked into it. Unfortunately, it is difficult
to get an index that everyone can agree upon. We would
use an index if we could find one that is understandable
to all and agreeable to all.
AGENCY NO. 40 AGENCY SIZE: 35
We have been asked many times to implement an
air pollution index. However, since air pollution is
too complex, the general public would not really
understand an air pollution index. We don’t believe
it is possible to construct an index that is truly
meaningful and sensible. Any index will inevitably
give values that contradict the public’s own ob-
servations and perception, and we don’t want to
make something that’s misleading. Thus, we give
the public the actual measured data; if they can’t
understand it, too bad. If we attempt to reduce
these complex data to some simple index, we’re just
kidding ourselves.
*NOTE THESE ARE INTERPRETATIONS BY THE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURING
TELEPHONE CONVERSATIONS.
142
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
AGENCIES NOT USING INDICES (Cont’d )
AGENCY NO. 41 AGENCY SIZE; 15
Ours is not really an index based on air quality;
instead, we report an “air pollution potential index”
which is based on meteorological conditions (i.e.,
ventilation) and informs the public whether they should
burn or not. We feel it is better to forecast forth-
Coming conditions than to report yesterday’s values.
It probably would be a good idea, however, for EPA to
come up with a basic index so that we could compare
conditions in different cities.
AGENCY NO. 42 AGENCY SIZE: 14
We don’t now use an index because our sampling
network previously has been too limited. Most indices
represent a “non—understandable, non—dimensional
nurriber.” Everyone seems to use an index, and they all
are doing it a bit differently; as a result, the indices
are really not interpretable. We might use a stand-
ardized index, however, if EPA were to propose one.
AGENCY NO. 43 AGENCY SIZE: 10
We do not now use an air pollution index,
because we never have found one that was satisfactory.
We would like one that includes particulates and SO 7 ;
it night possibly be beneficial to us.
AGENCY NO. 44 AGENCY SIZE: 76
We do not use an index; we do, however, routinely
predict the next day’s particulate level. I don’t
think a combined index really is clear to the public;
it can really confuse them. We prefer to encourase
them to use the scientific notation — — i.e., ug/m
With so many different air quality indices around,
“people really can get confused when they move from
city to city.” We think it would be best to 3 strive
to familiarize the general public with “ug/m particulate”
for example. They can become familiar with this scien-
tific notation just as they have learned to understand
wind speed in miles per hour and temperature in degrees.
Whenever we report our concentration data, we also list
the air quality standards in one column alongside the
data.
NOTE : THESE ARE INTERPRETATIONS BY TI lE INVESTIGATORS OF VIEWS EXPRESSED BY RESPONDENTS DURLNG
TELEPHONE CONVERSATIDNS.
143
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APPENDIX C. INFERRED COMMENTS FROM RESPONDENTS *
NCIES NOT USING INDICES (Cont’d )
AGENCY NO. 45 AGENCY SIZE: 45
We have no routine air monitoring data; thus,
there is no way for us to use an index. The data
we do collect is primarily for enforcement purposes
AGENCY NO. 46 AGENCY SIZE: 25
An air quality index is a good idea if its
meaning can be clearly explained to the public.
AGENCY NO. 47 AGENCY SIZE: 105
Several years ago, in order to maintain good
public relations, we were “pushed into” publishing
a daily air quality report consisting of a “good,”
“average,” or “poor” ratings. Due to its inherent
inadequacies, the system was discontinued about a
year ago. If a new index is established, it will
not be a combined index since combined indices do
not represent true air quality.
AGENCY NO. 48 AGENCY SIZE: 1 5
Our index was discontinued about a year ago
because it did not give a true indication of the
air quality. However, we still get requests for
it, and are currently considering implementing
a new index.
AGENCY NO. 49 AGENCY SIZE: (10
We used an index for a while and received
favorable public response, but we had to discontinue
it because parts of the media “sensationalized” the
higher index values by stating “the index is now at
80 and when it gets to 100 you will have to start
worrying.” In general, the public must fully under-
stand any index which is used.
* NOTE: THESE ARE INTERPRETATIONS RY THE INVESTIGATORS OF VtEWS EXPRESSED Y RESPONDENTS DURING
TELEPHONE CONVERSATIONs.
144
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APPENDIX D
EXAMPLES OF INDEX DISPLAY AND
DISSEMINATION TECHNIQUES
THE ATtANTA CONSTITUTION, Friday, D .c. 6, 1974
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Baltimore Morning Sun
November 22, 1974
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AIr gi3U do as ftnora at P
r’c
tWnf& i ts 1g r
Baltimore, Md.
Thursday, January30 197.5
Mr Quality Index
The air quality index In
the Washington area from 8
a.m. to 9 a.m. today was 11
for the pollutant 5ulfer diox-
ide. Index values between 0-
24 indicate good ajr quality.
ThE WASHINGTON POST flws Jaia. 3O, 1975
The Coundi sf Governments’ Air
Quality Index for yssterday showed lb.
blob readino In the Washington urea dur-
ins itte 2 to 3 p.m. period waS 19 for
the pollutant, ph@tOChei lCiI oxidents.
Index values between I and 24 indicate
good air quality. When the Index ex-
ceeds OO the air becomes hazardous,
and persona with lung, heart and eye
problems should restrict their activity.
Washington,
D.C.
145
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Minnesota
AIR POLLUTION INDEX
Duluth 13
Minneapolit 22
Good, 0 20. satisfactory. 21100; un
satisiactory. 101155; unhealthy, 1M•200.
Duluth
POST-BULLETIN, ROCHESTER, MINN., Thursday. Aug I, 1$7&...
24-Kour Air
PoII tj Ind.x: 32
The Air PoIIUtio Index is an aver-
age degree 01 air pollution for a 21-
hour period endIng 10 a.m. for
ReChe for. The index, complied at
the Public Health Centet- 415 4th St.
SE, combinee measur,, ,1ts and es-
timates of th, levels *1 three major
air pollutants h.r. aulplj,r dioxide,
carbon monoxide and particuiate
(dust). A reading .betwsee 0-25 is
“good”; between 26-100 is “satisfac-
tory”; between 101-155 is “Un-
satisfactory” arid between 156-200 is
“UflSatis lactory”.
Rochester
146
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New York
Buffalo Evening News
11/26/74
KnickerbOC1 er isiews
11/26/74
? 1F any,
Today’s NIagara Falls ruadln :
Sulfur Dioxide 0.03 Medium
Carbon MonoXide 2.9 Low
Soling (Dust) 0.3 Low
The readingS represent average air
pollut4on levels for a 24-hour period end-
ing at midnight as measured at the con-
tinuous sIc monitoring stations.
TM State Departflwnt of Enviroflrnefl
tal Conservation’s DivISlOfl of Air Re-
so cOS provides this key to interpretIng
the readings’
Sulfur DiOxIde—Cm parts per 1 -niillofl)
low less !hafl 03; medIum .03 to .00;
high greater than .08.
carbon MOfloXidO—(lfl parts pei- n Il-
lion): low less than 59- meoium. 5.0 to
15.0: hig4 greater than 5.O.
SOUInI—(lfl refleCiant units of dirt
elsade): low, less than 0.4; medIum, 0.4
to 0.7; high, greater than 0.7.
Buf falo
fr II ruiiuiu .’u’
Today Rating
Sulfur Dioxjde 0.02 Low
Carbon Monoxide 3.2 Low
Soiling 0.2 Low
Albany
N.Y.
24-Hr. Reading_—N FoecaSt’ ’
Toe,y’ Suffale reaolng
Sulfur Dioxide 0.01 Low
Carbon Monoxide 2.4 Low
Soling (Dust) 0.3 LoW
147
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Ohio
AIR POLLUTION INDIX
Today poIlqti ludex:
. indicatIng air of vary good
31 (very good). *ulltv. fla rnalor a)’ PoIMant during
the perIod ai pa s
kron Toledo
Tomorrows pollution forscaet8 170 V. 190 ( .
tr.fl 1y poor).
Cleveland
The Cincinnati Post, Friday, Nov. 22, 1974
Pollutlosi mdix
7 1* air pillutlon index of 9 am, was 42, whIch Is r ry asd, 1*11,, than
fkUlean .lr standard. At 4p.m. yesterday iso 04 whIch is riled vary
g d better tt an the clean air standard.
Ibe discomfort tevol r polMants Is ; liii waan5 Ipe,I sod lisa nse-
*c level O- .when all Indusfr . and auto., Ills main pS Iu$Or$,Ol air would be
0 dby Ihsgousrnortoccm.to a halt.
The Cincinnati Enquirer
November 22, 197)4
Weather
Mostly sunny today, high upper
408. Variable cloudiness tonight
and Saturday. Low tonight,
upper SOs. High Saturday around.
60. Mr Pollution Index, 45, very
good.
Details,, Map on Page 18
C i.ncinnat i
148
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Pennsylvania
The Pittsburgh Press
December 6, 1974
T__AIRIi4ETER
250 — - —
200 — - —
ISO — - -
I00—•
The air pollution Index at
10 a. m. today In downtown
Pittsburgh was 98.
This is 63 points over the
maximum level established by
county authorities as satisfac-
tory quality air.
Oth readings In the coun-
ty today include: Bellevue, 80;
Glassport, 82; Hazelwood No.
1, 92; Hazelwood No. 2, 63;
Liberty Borough, 87, and Lo-
gan’s Ferry Heights, 61.
Pittsburgh
Tuesday, Aug. 13, 1974 Phfladelpbia Inquirer
AIR QUALITY
Monday’s Pollution Index: 5.
The Air Pollution Index, compiled
the Philadelphia Air Mana emerit 5cr
vices, is a 1 (clean) to 10 (dirty) scale
based on measurements of sulphur
dioxide id particulate matter In th.
air in the last five years. Since conceri-
fretioris have dropped irs rec 5t yeerS,
the daily reaóinc usually is ri the lower
aJi of the scale.
Philadelphia
149
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AI PENDIX E
STANDARDIZED URBAN AIR QUALITY INDEX
The Standardized Urban Air Quality Index (SUAQI)
presented here is based On the results of this study and
the uniform index criteria Identified during this investiga-
tion (Chapter VI, Section 4). SUAQI is a type 5B 2 B index.
However, it could equally well have been a type 5D 2 3 index.
Since it is based on the best available current information,
this basic structure represents one feasible form that a
future SUAQI might take.
besides selecting the index structure, there are many
other problems which must be confronted by jurisdictions
adopting a uniform index. Some of these relate to the
governmental procedures required for the adoption of an
index, some relate to the siting of monitoring stations, and
some relate to the manner by which the index is reported to
the public. These problems are not dealt with here. However,
as discussed in Chapter VIII, it is hoped a document will be
completed which provides detailed procedures for adoption
and implementation of a uniform index.
The following discussion gives the basic structure of
SUAQI according to the order of the index classification
system (Chapter VI, Section 2).
150
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Number of Pollutants . Due to the seasonal variation
in pollutant concentrations and the emphasis on different
pollutants in different parts of the country, SUAQI in-
corporates all of the most common air pollutants. However,
SUAQI does not include pollutants for which standards do
not existe Since uniform NA.AQS have been adopted by the
Federal Government, the five pollutants covered by these
standards were chosen — — carbon monoxide, sulfur dioxide,
suspended particulate matter, nitrogen oxides, and photo—
chemical oxidants. Because of its structure, if the
number of NAAQS pollutants changes in the future, the SUAQI
will be able to accommodate such changes without modifying
its basic form.
Calculation Method . A linear function with nonconstant
coefficients (segmented linear function) is used. The SUAQI
breakpoints (Table E—l) are based on the NAAQS and Federal
Episode Criteria. A plot of each set of values (pollutant
concentration, K) gives a SUAQI function for each of the
five pollutants (Figures E—l to E-6). If new NAAQS are
adopted in the future, a new SUAQI function can easily be
drawn to accommodate it.
151
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Mode . Inasmuch as SUAQI is based on the NAA QS and
episode criteria, which do not include any standards for
the combinations of pollutants (except product S0 2 —COH),
the index can either be an individual or maximum type.
The maximum type has been selected, since it reports only
one pollutant index (the highest one), thus preventing the
public from becoming overwhelmed with too many index values.
However, in some cases it may be desirable to report an
index value for all pollutants which equal or exceed the
Primary NAI¼QS. The maximum mode also enables the greatest
utilization of existing monitoring equipment, which in most
cities is directed at the city’s problem pollutants.
Descriptor Categories . Inasmuch as the index
calculation is based on the NPAAQS and Federal Episode
Criteria, it is logical that the descriptor categories
be based on these same standards. As a result of the
findings of this study, three of four categories are used
to describe pollution levels. The four SUAQI categories
and their de scriptor words are shown in Table E-2.
“Hazardous” is used to describe air pollution levels at
and above the Alert ].evei. to prevent confusion when
pollt ion levels exceed this level but an Alert is not called.
152
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I-a
Ui
‘Secondary same as Primary NAAQS
NAAQS for this averaging time
TABLE E-1
BREM(POINTS FOR SUAQI
K
CO
ppm
SO
2
ppm
P1
ig/m
SO xPM
2 2
( .ig/m 3 )
ppm
Ox
ppm
Averaging Time
(hours)
NA
8
24
24
24
1
1
Secondary NAAQS
Primary NAAQS
Alert
Warning
Emergency
Significant Harm
50
100
200
300
400
500
/
9
15
30
40
50
/
0.14
0.3
0.6
0.8
1.0
150
260
375
625
875
1,000
/
/
65,000
261,000
393,000
490,000
W
/
0.6
1.2
1.6
2.0
a!
0.08
0.10
0.40
0.60
0.70
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TABLE E—2
SUAQI DESCRIPTOR CATEGORIES
SIJAQI
Standard
Descriptor
0- 50
At or below Secondary I AAQS
Good
51—100
At or below Primary NAAQS
Satisfactory
101—199
A1,ove Primary MAAQS
Unhealthful
200—299
Alert
300—399
400—499
Warning
Emergency
Hazardous
500 and
greater
.
S .gnificant Harm
154
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Figure E-1.
Carbon Monoxide, ppm
(8 hour running average)
SUAQI function for carbon monoxide
a
C ,,
500
400
300
200
100
0
0 10 20 30 40 50
155
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Sulfur Dioxide, ppm
(24 hour running a rage)
Figure E-2. SUAQI function for wifur dioxide
500
400
300
200
100
0
0
0.2 0.4 0.6 0.8 1.0
156
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400 600
Particulate Matterjag/m 3
(24 hour running avsrags)
Figure E-3. SUAQI function for particulate matter .
500
400
300
200
100
0
0 200
1000
157
-------
500 -
400
c i
300-
200 -
100
0 I I
0 10,000 20,000 30,000 40,000 50,000
Sulfur Dioxide X Particulate Matter, Jjg/m3) 2
(24 hour running average)
Figure E—4. SUAQI function for the product of sulfur dioxide
and particulate matter
158
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500
400
5 300’
(I,
200
100
0 I I I
0 1.0 2.0
Nitrogen Dioxide, ppm
(1 hour average)
Figure E-5. SUAQI function for rntrogen dioxide
159
-------
0 0.2 0.4 0.6 0.8
Oxidants, ppm
(1 hour average)
Figure E-8. SUAQI function for photochemical oxidants
a
0)
500
400
300
200
100
0
160
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APPENDIX F
PRIMARY STANDARDS INDEX
The Primary Standards Index (PSI) is a second example
of a possible standardized index and is derived from the
recently proposed Common Air Quality Reporting Format.
PSI was developed after reviewing the comments received from
some Federal, State, and local air pollution control officials
on SUAQI (Appendix B), and it reflects the opinion of some
reviewers that a standardized index should be simpler than
SUAQI and relate only to the Primary NAAQS and their as-
sociated health effects. ThUs, PSI has only two descriptor
categories (whereas SUAQI has four), and it relates directly
to health effects by reporting the adverse effects associated
with pollutant levels exceeding the Primary NAAQS.
PSI is a type 4C 2 B index and thus has the same structure
as SUAQI (5B 2 B), except PSI uses a linear (instead of a
segmented linear) calculation method. The following discussion
outlines the basic structure of PSI, according to the order
of the index classification system (Chapter VI, Section 2).
Other details of the index (implementation procedure, moni-
toring siting, and format) should be covered in the Index
Monitoring Guidelines document discussed in Chapter VIII.
Nurrtber of Pollutants . PSI includes all pollutants for
which a Primary NAAQS exists (presently four): carbon
161
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monoxide, sulfur dioxide, particulate matter, and oxidants.
Because PSI gives separate index values for each pollutant
an agency can select which of the four pollutants it wishes
to include in a PSI report.
Calculation Method . PSI is a linear function with a
constant coefficient of 100. Thus, it is a “percent—of—
standards index,’ which, f or each pollutant, gives the
percent of the corresponding Primary N AQS (Table F—i).
The PSI equation is given as:
PSI. KC.
1 1
where, 1< = 100/C; C. is the concentration of pollutant
; and C is the NI AQS for pollutant . Combining these
Si
definitions:
C.
PSI. = 100
1 C
S.
1
Using this equation, PSI values for new pollutants are
easily accommodated in the total index structure.
3e . In reporting PSI, either the individual index
values or the maximum value can be used. Alternatively,
one can report only those values which exceed the
162
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TABLE F-i
POSSIBLE ADVERSE HEALTH EFFECTS FOR PSI GREATER THAN 100
Pollutant
Averaging
Time
Primary
t s
ExplainatiOn Given when PSI > 100 (Unhealthy)
Co 8 9 ppm •Impaired exercise tolerance in persons with cardio-
vascular disease
1 35 ppm •Decreased physical performance in normal adults
SO 2 24 0.14 ppm •Increased hospital admissions for respiratory illness
•Aggravation of asthma and cardiorespiratory syrr toms
in elderly patients with related illness
TSP 24 260 pg/rn 3 •Aggravation of chronic lung disease and asthma
SAggravation of cardiorespiratory disease symptoms
in elderly patients with heart or chronic lung
disease
S Increased cough, chest discomfort, and restricted
activity
Ox 1 0.08 ppm SAggravation of chronic lung disease and asthma
•Irritation of the respiratory tract in healthy adults
•Decreasec3 visualy acuity; eye irritation
•Decreased cardiopulmonary reserve in healthy subjects
-------
Primary NAAQS. Such an approach gives an agency maximum
flexibility in using its existing monitoring network and
data to compute the index.
Descriptor Categories . Since PSI is based only on
one “breakpoint’, the Primary NAAQS, only two descriptor
categories are needed:
TABLE F-2
PSI DESCRIPTOR CATEGORIES
PSI
Standard
Descriptor
0-100
> 100
At or below Primary NAAQS
Above Primary NAAQS
Satisfactory
Unhealthful
In addition to these descriptor words, the associated
possible adverse health effects listed in Table F—i are
reported for those pollutants exceeding the Primary NAAQS
(PSI > 100). In the cases when the Federal Episode Criteria
apply (Table 2, page 20), the air quality may still be
termed ‘ unhealthfu1” and used in conjunction with the Alert,
Warning, and Emergency stage designations.
164
U, 8. OOUR MEN ’r PRIN7ING OYVICE 19 E-3 4J 6BO
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