vvEPA
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/4-87-005
April 1987
Air
Guideline on
Exceptions to
Data Requirements
for Determining
Attainment of
Particulate Matter
Standards
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EPA-450 4-87-005
April 1987
Guideline on Exceptions to
Data Requirements for
Determining Attainment of
Particulate Matter Standards
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Monitoring and Data Analysis Division
Research Triangle Park NC 27711
U.S. Environmental Protection Agency
Beglon 5, Library |f>PL-16)
250 S. Dearbcro Bt -set. Room 1670
Chicago, 1L 60604
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PREFACE
This report has been reviewed by the Office of Air Quality Planning and
Standards, U.S. Environmental Protection Agency and approved for publica-
tion. Any mention of trade names or commercial products is not intended
to constitute endorsement or recommendation for use.
The report was prepared by Systems Applications, Inc. (SAI) of San Rafael,
California under EPA Contracts 68-02-3848 and 68-02-4335.
The principal SAI authors are Alison K. Pollack and Anthony D. Thrall.
The EPA project officer is Neil H. Frank.
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ABSTRACT
This guideline document describes procedures that can be used to
demonstrate attainment of the particulate matter standards for those sites
that do not satisfy the minimum data requirements. In order to apply
these procedures, minimum quarterly data requirements must be met. The
procedures involve the substitution of appropriate data for the missing
samples; collocated TSP can be substituted for missing PM 10 samples, and
substitutions from available monitoring data are also allowed. Under
certain conditions, model-derived estimates of annual means and number of
exceedances may also be used. Four examples demonstrate the use of the
procedures under various scenarios.
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CONTENTS
Section Page
1 INTRODUCTION AND BACKGROUND 1
2 ELIGIBILITY REQUIREMENTS 4
3 PROCEDURES FOR DETERMINING ATTAINMENT OF
THE PARTICULATE MATTER STANDARDS 6
4 EXAMPLES 9
Example I: Use of Collocated TSP Data 9
Example II: Use of Substituted PM 10 Data
from Representative Quarters 11
Example III: Use of Modeling Data 12
Example IV: Combined Use of Substituted
PM 10 Data and Modeling Data 13
5 REFERENCES 16
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Section 1
INTRODUCTION AND BACKGROUND
The U.S. Environmental Protection Agency (EPA) recently revised the
National Ambient Air Quality Standards (NAAQS) for participate matter
(PM). While the former standards for particulate matter were based on
total suspended particulates (TSP), the new standards are based on
particles with an aerodynamic diameter less than 10 micrometers, hereafter
referred to as PM 10.
The former primary particulate matter standards specified that the annual
geometric mean TSP concentration at a site was not to exceed 75 vg/m , and
that 24-hour TSP concentrations were not to exceed 260 vg/nr more than
once per year. The new primary standards, based on PM 10, are sta-
tistically based, and should provide more stable objectives for developing
emission control strategies because they are expressed as expected annual
values (Curran, 1979; Hayes et al., 1983). The expected annual arithmetic
mean is not to exceed 50 vg/m , and the expected number of concentrations
above 150 vg/m3 per year is not to exceed one.
Appendix K to 40 CFR, Part 50: "Interpretation of the National Ambient Air
Quality Standards for Particulate Matter," describes the calculation of
expected annual average and expected annual exceedances that are used to
determine attainment. These calculations are generally to be based on the
most recent three calendar years of particulate data. The expected annual
average is calculated as the average of the three annual means. The
expected number of annual exceedances is calculated as the average of the
number of exceedances for each of the three years; if data in a given year
are incomplete, but meet the minimum requirements specified in Appendix K,
the annual exceedance rate is estimated from the observed exceedance rate.
1
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The required sampling frequency for PM 10 the first year is one 24-hour
sample every six days, every two days, or every day, depending on the
probability of nonattainment of the PM 10 standards; for subsequent years
the sampling frequency will depend on site attainment status, as described
in 40 CFR 58.13. However, the EPA recognizes that data from some
scheduled sampling days may be missing for any of a number of reasons,
e.g., damaged filters (sample loss), miscalibrated equipment, or other
equipment failure. Appendix K specifies a minimum 75 percent data capture
rate of required PM10 samples, but states that: "Data not meeting these
criteria may also suffice to show attainment, however, such exceptions
will have to be approved by the Regional Administrator in accordance with
established guidelines."
The present document is intended to provide guidance for such exceptions
to the data requirements, but it is not intended to list all possible
situations in which data may be acceptable; other procedures besides those
described in this guideline may be used to determine attainment of the
particulate matter standards, if approved by the Regional Administrator.
Eligibility requirements for the use of these guidelines are given in Sec-
tion 2. Section 3 describes specific procedures that may be used to
determine attainment status of the 24-hour and annual standards; and
examples of the application of these procedures are given in Section 4.
These guidelines were formed with four principles in mind. First, the
procedures should be relatively simple and not require elaborate computer
programs (except when air quality models are used). Second, the proce-
dures should be conservative, so that there is a low probability of
falsely classifying a site as attainment when it is in fact nonattain-
ment. Third, it is assumed that monitoring programs are designed so that,
on the average, the data capture rate exceeds the minimum specified in
Appendix K and that certain days of the week or seasons of the year are
Data capture rate is defined as the number of valid samples as a
percentage of the number of scheduled sampling days.
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not systematically excluded. These guidelines are not intended to replace
Appendix K and become de facto standards. Fourth, the estimated annual
number of exceedances and estimated annual average concentrations derived
from procedures specified in this guideline shall not be used to establish
eligibility for any further adjustments to data in order to demonstrate
attainment, such as those permitted by the Guideline on Accounting for
Trends in Emission and Air Quality Data (EPA, 1987a).
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Section 2
ELIGIBILITY REQUIREMENTS
The procedures described in this document may, under certain conditions,
be used to show attainment of the particulate matter standards. As dis-
cussed in Appendix K, nonattainment of the standards can also be shown
with less than the amount of data required, without using the procedures
in this guideline; e.g., if there are four observed exceedances in a
single year for a site regardless of sampling frequency.
The EPA has defined the three-year minimum data requirements in Appendix K
to correspond to an achievable data capture of 75 percent per calendar
quarter. The EPA does recognize, however, that extenuating circumstances
can lead to even more missing data. Nevertheless, in order to apply the
procedures of this guideline, justification for the missing samples must
be provided.
The minimum requirements for use of these guideline procedures are as fol-
lows:
(1) If two or more years of monitoring data are available, there
must be at least 50 percent of the required samples in each
quarter. At least one of the years must indicate attainment
based on monitored concentrations that meet the minimum data
requirements and follow the round-off conventions in Appendix K.
(2) If only one year of representative PM 10 data with everyday
sampling is available, then it may be considered if the data
capture rate exceeds 75 percent in each quarter. The procedures
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in this guideline cannot be used to demonstrate attainment if
there is only one year of data and the data capture rate is
below 75 percent in one or more quarters. However, because of
the possibility of mid-year startup monitoring, representative
data from four consecutive calendar quarters of everyday samp-
ling may be used; in such a case the data capture rate must also
be at least 75 percent per quarter.
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Section 3
PROCEDURES FOR DETERMINING ATTAINMENT
OF THE PARTICULATE MATTER STANDARDS
If the available particulate matter data do not satisfy the minimum three-
year data requirements of Appendix K, but do satisfy the less restrictive
data requirements described in Section 2 of this document, then any one of
the following procedures may be used to demonstrate attainment of the
particulate matter standards on the equivalent basis of three years:
(1) If three years of PM 10 data are available and the eligibility
requirements of Section 2 of this guideline are met, substitu-
tions may be made for scheduled sampling days with missing
particulate matter data. Substitutions must be made for every
scheduled sampling day with missing data in each quarter that
does not satisfy the minimum data requirements in Appendix K.
The substituted value may be one of two kinds of data:
(a) Collocated TSP data may be substituted for missing PM 10
data. If collocated TSP data are available for those
scheduled sampling days with missing PM 10 data, and if
the number of such days added to the-number of days with
valid PM 10 data is greater than or equal to the minimum
specified in Appendix K, then the TSP data may be used
in place of the missing PM 10 data to show attainment,
using the calculations of Appendix K. All available TSP
data from scheduled sampling days in which there are no
valid PM 10 data must be used in the calculation to show
attainment.
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(b) Monitoring data from the same quarter in any one of the
years used to determine attainment may be substituted
for missing PM 10 data. The maximum PM 10 (or TSP)
value that was observed in that quarter over the attain-
ment test period (e.g., the last three years) may be
substituted for missing scheduled sampling days, pro-
vided emissions and meteorology for these quarters are
representative of the emissions and meteorology for the
quarter in question. Data from representative adjacent
monitoring sites may be used to substantiate the repre-
sentativeness of the substituted data.
After substitutions have been made, calculations of annual
averages and expected exceedance rates proceed according to Sec-
tions 3 and 4 of Appendix K.
(2) Modeling data for an entire year may be used in place of moni-
toring data for a year with missing data, provided that the
EPA's Guideline idn Air Quality Models (EPA, 1986) has been fol-
lowed and that the model is one of those listed in EPA's PM 10
SIP Development Guidance (EPA, 1987b). Model-derived estimates
of the annual mean and annual exceedance rate can be used in the
calculations of expected annual mean and expected annual exceed-
ance rate specified in Appendix K, unless monitoring data show
higher values. For the one or two years of available PM 10 data
that will be used in conjunction with the modeling data, substi-
tution must be made as described in procedure (1) for any quar-
ters that have data for less than 75 percent of the scheduled
sampling days.
(3) Attainment can be determined on the basis of only one or two
years of PM 10 data in the absence of modeling data if the fol-
lowing conditions are met:
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(a) The eligibility requirements of Section 2 are satisfied.
(b) Emissions and meteorological conditions are consistent
in the three years of concern.
(c) PM 10 data are available on sampling days with repre-
sentative meteorological conditions.
Substitutions must be made in each calendar quarter with less than 75
percent of scheduled samples. The expected annual exceedance rate
and annual average can then be calculated using the one or two years
of available data (with substitutions, if necessary).
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Section 4
EXAMPLES
This section illustrates the use of the procedures described in Section
3. Annual means and exceedance rates are derived for each of three years;
the expected annual means are then compared to the annual average PM 10
NAAQS of 50 yg/m3, and the expected annual exceedances of the 24-hour
average PM 10 standard of 150 yg/m are examined to determine attainment
status. In these examples all concentrations are expressed as yg/m, and
the Appendix K rounding conventions are followed.
EXAMPLE I: USE OF COLLOCATED TSP DATA
In this simple case there is just one PM 10 sample less than the number
required by Appendix K. Consider a PM 10 monitor on a once-in-six-day
schedule with a collocated TSP monitor and three years of data. In the
first and third years the annual average PM 10 concentrations are 40.2 and
36.3 yg/m3, respectively, and there are no observed exceedances of the 24-
hour standard. In the third quarter of the second year (see Table 1) only
11 samples were obtained from the 16 scheduled sampling days, one less
than the 12 per quarter required by Appendix K. The average PM 10 concen-
tration of the 11 samples is 38.1 yg/m3. Suppose that collocated TSP 24-
hour averages of 97, 65, and 134 yg/m are available for only three of the
five days with missing PM 10 averages. These three TSP samples, combined
with the 11 PM 10 samples, constitute a valid quarter (consisting of 14
samples) and can therefore be used to demonstrate attainment. The third
quarter average of the second year would then be calculated as
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TABLE 1. Quarterly PM 10 statistics
for the second year in Examples I,
II, and III (all concentrations are
in pg/m3).
Quarter
1
2
3
4
Number of
Samples
14
13
11
15
*
Quarterly Average
*q
41.6
39.9
38.1
43.3
Calculated from available PM 10
concentrations.
Annual averages for first and third
years, are, respectively,
P! = 40.2 yg/m
y, = 36.3 yg/m
10
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(11 x 38.1) + 97 + 65 + 134 _ ci i
X3 " 11+3 ~
The average for the second year is then
- _ 41.6 + 39.9 + 51.1 + 43.3
*2 ~ 4
•
and the three-year average is
Y = 40.2 + 44.1 + 36.23 = 4Q 2
Following Appendix K conventions, the three-year average is rounded to 40,
O
which is below the standard of 50 pg/m ; thus attainment of the annual
standard is shown.
Let us assume there were no observed PM 10 exceedances in the second
year. Then, since the three substituted TSP values are all below the
24-hour PM 10 standard, the second year is estimated to have no exceed-
ances. Since there were no observed exceedances in either the first or
the third years, then the^expected number of exceedances is estimated to
be 0, and the 24-hour attainment test is passed.
EXAMPLE II: USE OF SUBSTITUTED PM 10 DATA FROM REPRESENTATIVE QUARTERS
Consider the same set of PM 10 observations as in Example I (see Table 1),
except that no collocated TSP data are available. Thus, five substitu-
tions must be made for the five scheduled PM 10 sampling days missing in
the third quarter of the second year. Suppose it has been shown that
emissions and meteorology of the quarter in question are typical for the
third quarter in the three-year period and that data from nearby monitors
support this. In this case data from other years can be substituted.
To estimate the mean for the third quarter, the maximum PM 10 concentra-
tion observed in the third quarter in the most recent three years is sub-
stituted for all five missing samples. Let us say this maximum is 96
11
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yg/nr\ Then the third quarter average for the second year is calculated
as
- _ (11 x 38.1) + (5 x 96) _ ,fi ?
X3 " 11 + 5 ~ &t>-^ *
When averaged with the other quarterly averages of the second year, y"2 is
found to be 45.3 (using Appendix K rounding conventions), and the three-
year average is thus 41 (rounded to the nearest integer) which is below
the annual standard of 50 yg/m . Thus despite the substitution of five
high 24-hour averages, attainment of the annual standard is still shown.
With those substitutions, there are still no exceedances of the 24-hour
standard.
EXAMPLE III: USE OF MODELING DATA
Consider again the same set of PM 10 observations of Example I (see Table
1). As in Example I, five scheduled sampling days of PM 10 data are
missing but data are available from a collocated TSP monitor for three of
those days. On these three days, the 24-hour average TSP concentrations
are 97, 65, and 160 yg/m. If the concentration of 160 yg/nr were used as
a substitute, there would be approximately six estimated exceedances for
the quarter (using the calculations in Section 3 of Appendix K), and the
site would not meet the standard. Although the two lower TSP concentra-
tions combined with the 11 available PM 10 concentrations would meet
Appendix K requirements of 12 samples per quarter, this is not a valid
procedure, since one cannot selectively use TSP concentrations to meet the
Appendix K requirements.
The site coordinator decides to use modeling data to estimate the number
of exceedances and annual mean for the whole year. The EPA guidelines on
the use of air quality models have been followed and the model is con-
sistent with SIP guidelines. The model predicts that the maximum 24-hour
average PM 10 concentration would have been 165 yg/m , and that the
second-highest concentration for the year would have been 140 yg/rn^.
12
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Thus, the model predicts one exceedance of the 24-hour standard for the
second year. Since there were no observed exceedances in the first and
third years, the expected annual number of exceedances is 0.3, and attain-
ment of the 24-hour standard is demonstrated. The second-year annual
o
average estimated by the model is 44.9 yg/m , which is consistent with the
observed monitoring data. The three-year average is then
40.2 + 44.9 + 36.3
which is below the expected annual average standard (50 yg/m )
EXAMPLE IV: COMBINED USE OF SUBSTITUTED PM 10 DATA AND MODELING DATA
In this example a site has only two years of sampling data available for a
required sampling schedule of every day. The number of PM 10 samples in
each quarter and the quarterly means and exceedance rates for the two
years are shown in Table 2. Only 289 valid samples were collected the
first year and 278 in the second year. The data capture rates for the
first two quarters of the second year fall short of the 75 percent
required by Appendix K. In each of the eight quarters, however, there are
at least 45 samples (the minimum required by Section 2 of this guideline).
In addition, there were no exceedances in the first year, and the mean
concentration for that year is below the annual mean standard, so the site
qualifies for the procedures of this guideline.
To demonstrate attainment, the site coordinator decides to substitute PM
10 data from representative quarters for the missing monitoring data in
the two years, and then to use estimates derived from air quality models
for the third year. Since the first two quarters of the second year have
fewer than 68 days each (i.e., less than 75 percent data capture), substi-
tutions must be made for all missing days in those quarters. Since emis-
sions and meteorology in those quarters were similar to emissions and
13
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TABLE 2. Quarterly PM 10 statistics and calculations for the two years in
Example IV. All concentrations are in yg/m .
A. First year (no substitutions
required).
Quarter
1
2
3
4
Total
No. of
Samples
68
75
77
69
289
Mean
42.6
47.8
52.1
45.1
Max.
Cone.
84
67
126
72
Annual mean = (42.6 + 47.8 + 52.1 + 45.1)/4 = 46.9
B. Second year (substitutions required for first two quarters).
Quarter
1
2
3
4
Total
No. of
Samples
53
66
82
77
278
Observed
Mean
44.8
39.6
61.3
43.1
Max.
Cone.
72
69
165
77
Substitute
Cone.
84
69
No. of
Substitutes
37
22
Estimated
Mean
60.9
45.4
61.3
43.1
Estimated annual mean = (60.9 + 45.4 + 61.3 + 43.1)/4 = 52.7
14
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meteorology in the first two quarters of the first year, the site coordi-
nator chooses to fill in the missing days with the maximum concentrations
observed in the quarters over both years. The highest 24-hour PM 10 con-
centration in the first quarter of both years was 84 yg/m ; for the next
quarter the maximum over both years was 69 yg/m3. These two values are
substituted appropriately for each of the missing days in the first two
quarters of the second year. The means calculated from the monitored and
substituted concentrations are given in Table 2; the estimated annual
means are 46.9 and 52.7 yg/m3 (using Appendix K round-off conventions).
In the two years of monitoring data there was only one exceedance of the
o
24-hour PM 10 standard; a concentration of 165 yg/m was obtained in the
third quarter of the second year. For that quarter, however, there were
10 scheduled sampling days with missing data, and so the number of exceed-
ances must be estimated. Using the calculations in Section 3 of Appendix
K, the estimated number of exceedances for the quarter is 1.1, and the
total estimated number of exceedances for the second year is therefore
also 1.1 (since there are no exceedances in the other three quarters).
Modeling data are used to estimate the number of exceedances and annual
mean for the third year. The EPA guidelines on the use of air quality
models have been followed and the model is consistent with SIP guidance.
The model predicts one exceedance of the 24-hour PM 10 standard in the
q
third year and an annual average PM 10 concentration of 47.3 yg/m for the
year.
The expected annual concentration is then calculated as the average of
•3 o
46.9 yg/m (observed in the first year), 52.7 yg/m (estimated after sub-
stitutions for the second year), and 47.3 yg/m3 (predicted by the model
for the third year). The three-year average (rounded to the nearest inte-
ger) is 49 yg/m3, which is below the standard of 50 yg/m3. In a similar
fashion, the expected annual number of exceedances is calculated as the
average of 0 (observed in the first year), 1.1 (estimated for the second
year), and 1 (predicted by the model for the third year). The three-year
average, rounded to one decimal place, is 0.7, so the site is in attain-
ment of both the annual and the 24-hour standard.
15
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Section 5
REFERENCES
Curran, T. C. 1979. "Statistical Format of Air Quality Standards." Pro-
ceedings; Quality Assurance in Air Pollution Measurement. Air Pol-
lution Control Association (Specialty Conference, New Orleans,
Louisiana, March 11-14, 1979).
EPA. 1986. Guideline on Air Quality Models. U.S. Environmental Protec-
tion Agency (EPA-450/2-78-027R).
EPA. 1987a. "Guideline on Accounting for Trends in Emission and Air
Quality Data." U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle Park, North
Carolina (EPA-450/4-87-006).
EPA. 19875. "PM 10 SIP Development Guideline." U.S. Environmental
Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, North Carolina (EPA-450/4-86-017).
Hayes, S., C. S. Burton, J. L. Haney, and J. L. Baptista. 1983. "Alter-
native Forms of the Short-Term National Air Quality Standards for
Sulfur Dioxide." Systems Applications, Inc., San Rafael, Cali-fornia
(SYSAPP-83/113).
16
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing]
1. REPORT NO.
EPA 450/4-87-005
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Guideline on Exceptions to Data Requirements for
Determining Attainment of Particulate Matter
Standards
5. REPORT DATE
April 1987
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PER,F_OF1MING ORGANIZATION NAME AND ADDRESS
US Environmental Protection Agency
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This guideline document describes procedures that can be used to
demonstrate attainment of the particulate matter standards for those sites
that do not satisfy the minimum data requirements. In order to apply
these procedures, minimum quarterly data requirements must be met. The
procedures involve the substitution of appropriate data for the missing
samples; collocated TSP can be substituted for missing PM 10 samples, and
substitutions from available monitoring data are also allowed. Under
certain conditions, model-derived estimates of annual means and number of
exceedances may also be used. Four examples demonstrate the use of the
procedures under various scenarios.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COS AT I F-ield/Group
PM10
Particulate Matter
National Ambient Air Quality Standards
18 DISTRIBUTION STATEMENT
Release Unlimited
19 SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
20
20 SECURITY CLASS (Tins page I
! Unclassified
22. PRICE
EPA Form 2220-1 'Rev. 4-77) PHEVOUS ECITION 's
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hicago. 1L 60604
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