~&EPA 

United States Office of Air Quality EPA-4501 4-87 -005 

Environmental Prvtection Planning and Standards April 1987 

Agency • - R"esearcli Triangle Park NC 27711 

-

, Guideline on 

Exceptions to 

Data Requirements 

for Determining 

Attainment of 

Particulate Matter 

Standards 
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 

EPA-450 4-87 -005 

April 1987 

U.S. Environmental Protection Agency, 

Region 5, Lihrary (:'PL-16) 

230 S. Deal'Oc.rn St 'eet, 1toom 1670 

Chicago, 1L 60604 
PREFACE 

This report has been reviewed by the Office of Air Quality Planning and 

Standards, U.S. Environmental Protection Agency and approved for publication. 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. (SAl) of San Rafael, 

California under EPA Contracts 68-02-3848 and 68-02-4335. 

The principal SAl authors are Alison K. Pollack and Anthony D. Thrall. 

The EPA project officer ;s Neil H. Frank. 

; ; 
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 quarterl,y 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. 

iii 
CONTENTS 

Section 

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 Representa~1ve 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 

;v 
Section 1 

INTRODUCTION AND BACKGROUND 

The U.S. Environmental Protection Agency (EPA) recently revised the 

National Ambient Air Quality Standards (NAAQS) for particulate 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 ~g/m3, and 

that 24-hour TSP concentrations were not to exceed 260 ~g/m3 more than 

once per year. The new primary standards, based on PM 10, are statistically 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 ~g/m3, and the expected number of concentrations 

above 150 ~g/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 
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 Section 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 w~re 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). S~condt the procedures should be conservative, so that there is a low probability of 

falsely classifying a site as attainment when it is in fact nonattainmente 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. 

2 
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). 

3 
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 discussed 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 follows: 

(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 

4 
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 sampling may be used; in such a case the data capture rate must also 

be at least 75 percent per quarter. 

5 
Section 3 

PROCEDURES FOR DETERMINING ATTAINMENT 

OF THE PARTICULATE MATTER STANDARDS 

If the available particulate matter data do not satisfy the minimum threeyear data requirements of Appendix K, but do satisfy the less restrictive 

data requirements described in Section 2 of this document, then anyone 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, substitutions 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. 

6 
(b) Monitoring data from the same quarter in anyone 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 attainment test period (e.g., the last three years) may be 

substituted for missing scheduled sampling days, provided 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 representativeness of the substituted data. 

After sUbstitutions have been made, calculations of annual 

averages and expected exceedance rates proceed according to Sections 3 and 4 of Appendix K. 

(2) Modeling data for an entire year may be used in place of monitoring data for a year with missing data, provided that the 

EPA's Guideline:on Air Quality Models (EPA, 1986) has been followed 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 exceedance 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, substitution must be made as described in procedure (1) for any quarters 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 following conditions are met: 

7 
(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 representative 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). 

8 
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 ~g/m3, and the expected annual exceedances of the 24-hour 

average PM 10 standard of 150 ~g/m3 are examined to determine attainment 

status. In these examples all concentrations are expressed as ~g/m3, 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 ~g/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 concentration of the 11 samples is 38.1 ~g/m3. Suppose that collocated TSP 24-

hour averages of 97, 65, and 134 ~g/m3 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 

9 
TABLE 1. Quarterly PM 10 statistics 

for the second year in Examples If 

II, and III (all concentrations are 

in llg/m3). 

Number of Quarterly Average * 

Quarter Samples 

* 

1 

2 

3 

4 

14 

13 

11 

15 

41.6 

39.9 

38.1 

43.3 

Calculated from available PM 10 

concentrations. 

Annual averages for first and third 

years, are, respectively, 

- - 3 Yl = 40.2 )Jg/m 

3 Y3 = 36.3 JJg/m 

10 
- _ (11 x 38.1) + 97 + 65 + 134 - 51 1 x3 - 11 + 3 - • 

The average for the second year is then 

Y2 = 

41.6 + 39.9 : 51.1 + 43.3 = 44.1 , 

• and the three-year average is 

y = 40.2 + 4431 + 36.23 = 40.2 

Following Appendix K conventions, the three-year average is rounded to 40, 

which is below the standard of 50 ~g/m3; 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 exceedances. 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 substitutions must be made for the five scheduled PM 10 sampliD9 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 concentration observed in the third quarter in the most recent three years is substituted for all five missing samples. Let us say this maximum ;s 96 

11 
~g/m3. Then the third quarter average for the second year is calculated 

as 

(11 x 38.1) + (5 x 96) = 

x3 = 11 + 5 56.2 

When averaged with the other quarterly averages of the second year, Y2 is 

found to be 45.3 (using Appendix K rounding conventions), and the threeyear average is thus 41 (rounded to the nearest integer) which is below 

the annual standard of 50 ~g/m3. Thus despite the substitution of five 

high 24-hour averages, attainment of the annual standard is still shown. 

With those substitutions, there ar.e 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 ~g/m3. If the concentration of 160 ~g/m3 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 concentrations 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 consistent with SIP guidelines. The model predicts that the maximum 24-hour 

average PM 10 concentration would have been 165 ~g/m3, and that the 

second-highest concentration for the year would have been 140 ~g/m3. 

12 
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 attainment of the 24-hour standard is demonstrated. The second-year annual 

average estimated by the model is 44.9 ~g/m3, which is consistent with the 

observed monitoring data. The three-year average is then 

-y _ 40.2 + 44.9 + 36.3 = 40 - 3 ' 

which is below the expected annual average standard (50 ~g/m3). 

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), substitutions must be made for all missing days in those quarters. Since emissions and meteorology in those quarters were similar to emissions and 

13 
TABLE 2. Quarterly PM 10 statistics and calculations for the two years in 

Example IV. All concentrations are in ~g/m3. 

A. First year (no substitutions 

required). 

No. of Max. 

Quarter Samples Mean Conc. 

1 68 42.6 84 

2 75 47.8 67 

3 77 52.1 126 

4 69 45.1 72 

Total 289 

Annual mean = (42.6 + 47.8 + 52.1 + 45.1)/4 = 46.9 

B. Second year (su~stitutions required for first two quarters). ~ 

No. of Observed Max. Substitute No. of Estimated 

Quarter Samples Mean Conc. Conc. Substitutes Mean 

1 53 44.8 72 84 37 60.9 

2 66 39.6 69 69 22 45.4 

3 82 61.3 165 61.3 

4 77 43.1 77 43.1 

Total 278 

Estimated annual mean = (60.9 + 45.4 + 61.3 + 43.1}/4 = 52.7 

14 
meteorology in the first two quarters of the first year, the site coordinator chooses to fill in the missing days with the maximum concentrations 

observed in the quarters over both years. The highest 24-hour PM 10 concentration in the first quarter of both years was 84 ~g/m3; for the next 

quarter the maximum over both years was 69 ~g/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 ~g/m3 (using Appendix K round-off conventions). 

In the two years of monitoring data there was only one exceedance of the 

24-hour PM 10 standard; a concent~ation of 165 ~g/m3 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 exceedances 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 

third year and an annual average PM 10 concentration of 47.3 ~g/m3 for the 

year. 

The expected annual concentration is then calculated as the average of 

46.9 ~g/m3 (observed in the first year), 52.7 ~g/m3 (estimated after substitutions for the second year), and 47.3 ~g/m3 (predicted by the model 

for the third year). The three-year average (rounded to the nearest integer) is 49 ~g/m3, which is below the standard of 50 ~g/m3. In a similar 

fashion, the expected annual number of exceedances ;s 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 attainment of both the annual and the 24-hour standard. 

15 
Section 5 

REFERENCES 

Curran, T. C. 1979. "Statistical Format of Air Quality Standards." Proceedings: Quality Assurance in Air Pollution Measurement. Air Pollution Control Association (Specialty Conference, New Orleans, 

louisiana, March 11-14, 1979). 

EPA. 1986. Guideline on Air Quality Models. U.S. Environmental Protection 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. 1987b. "PM 10 SIP D~velopment 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. "Alternative Forms of the Short-Term National Air Quality Standards for 

Sulfur Dioxide." Systems Applications, Inc., San Rafael, California 

(SYSAPP-83/113). 

16 
TECHNICAL REPORT DATA 

(Please read Instructions on the ,el'erse before completing) 

1. REPORT NO. 

1

2

. 

3. RECIPIENT'S ACCESSION NO. 

EPA 450/4-87-00S 

4. TITLE AND SUBTITLE 5. REPORT DATE 

Guideline on Exceptions to Data Requirements for Apri 1 1987 

Determining Attainment of Particulate Matter 6. PERFORMING ORGANIZATION CODE 

. Standards 7. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NO. -

-

~ 

9. PE~'S0frIN13 ORGANI€AfICW NAME A.ND A~DRESS 10. PROGRAM ELEMENT NO. nVlronmen a rotectlon gency 

Office of Air and Radiation 

Office of Air Quality Planning and Standards 11. CONTRACT/GRANT NO. 

Research Triangle Park, NC 27711 

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 P~1 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 

a. DESCRIPTORS b.IDENTIFIERS/OPEN ENDED TERMS c. COS A T I held/Group 

PMlO 

Particulate Matter 

National Ambient Air Quality Standards 

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