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Pb NAAQS Data Handling ~ Appendix R

Training Session: Lead Monitoring to Support the Newly Revised NAAQS Data Handling for NAAQS Comparisons Mark Schmidt EPA/OAQPS/AQAD/. Pb NAAQS Data Handling ~ Appendix R. 40 CFR Pt. 50, Appendix R Where can you get a copy of Appendix R? What is the new Pb NAAQS?

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Pb NAAQS Data Handling ~ Appendix R

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  1. Training Session: Lead Monitoring to Support the Newly Revised NAAQSData Handling for NAAQS Comparisons Mark SchmidtEPA/OAQPS/AQAD/

  2. Pb NAAQS Data Handling ~ Appendix R 40 CFR Pt. 50, Appendix R • Where can you get a copy of Appendix R? • What is the new Pb NAAQS? • What data are compared to the NAAQS? • How are data compared to the NAAQS? • Special situations? • Who will make the calculations?

  3. App. R starts on … FR Page 67054 (Page 82 / 100 of the PDF) Where to obtain a copy of Appendix R • EPA’s Technology Transfer Network (TTN) website • TTN > NAAQS > Lead Standards > 2005-2008 Review > FR Notices > “Final Revisions” file (http://www.epa.gov/fedrgstr/EPA-AIR/2008/November/Day-12/a25654.pdf) • GPO’s Electronic Code of Federal Regulations (e-CFR) website • www.gpoaccess.gov/ecfr • Title 40 > Part 50 > …

  4. NAAQS Level: Old versus New NAAQS • Old NAAQS level was 1.5 µg/m3; new NAAQS level is 0.15 µg/m3 • The new NAAQS level is one tenth (1/10th) the previous level! NAAQS Indicator: “Old” (1978) versus “New” (2008) NAAQS • Both specified in terms of the Pb content in Total Suspended Particulate (TSP), “Pb-TSP”. • New NAAQS also permits Pb measured in PM10 (“Pb-PM10”) to be used to show violations ... but not to show adherence • Old NAAQS based on concentrations reported at “Standard Conditions” (STP: 760mm Hg, 20C) but new NAAQS based on concentrations reported at “Local Conditions” (LC) • Typically, not big differences in STP- and LC-stated concentrations at most sites

  5. NAAQS Evaluation Period: Old versus New NAAQS • Old NAAQS had 1-year “look” for designations and 2-year evaluation period for redesignations • New NAAQS will use 3-year look for original designations and also redesignations NAAQS Averaging Time & Form: Old versus New NAAQS • Both specified as “not be exceeded” maximum 3-month average • Old NAAQS based on calendar quarters; new NAAQS based on “rolling” 3-month averages • Also, the 3-month averages (for Old versus New) are calculated slightly different Next few slides “show” the differences …

  6. Averaging Time & Evaluation Period: Old (1978) Pb NAAQS Year 2 Year 1 1 5 2 6 3 7 4 8 • NAAQS compliance based on two years of data • Averaging time was calendar quarter … 8 averaging periods in two years

  7. Year 3 Averaging Time & Evaluation Period: New (2008) Pb NAAQS Year 1 Year 2 • NAAQS compliance is based on a “3-year” evaluation period. • Averaging time is rolling 3-month (a.k.a. “rolling quarter”) … … every consecutive 3-month period (not just calendar quarters) • Each month is included in three monthly averages. Example: March included in January/February/March mean, February/March/April mean, and March/April/May mean • The end month used to identify 3-month periods.

  8. Previous year 1 13 14 15 25 26 27 2 3 4 5 6 16 17 18 28 29 30 7 8 9 19 20 21 31 32 33 10 11 12 34 35 22 23 24 36 Averaging Time & Evaluation Period: New (2008) Pb NAAQS Year 3 Year 1 Year 2 • First 3-month period in the “3-year” evaluation period is Nov (previous yr) / Dec (prev. yr) / Jan (current yr). Second 3-month period in the “3-year” look is Dec (prev. yr) / Jan (cur. yr) / Feb (cur. yr). • There are thirty-six (36) 3-month averaging periods in the “3-year” evaluation period. Thus, really 38 months are used to determine compliance but two of those months are also used in the next (/previous) evaluation period

  9. Calculating 3-Month Averages: Old (1978) Pb NAAQS • Calculations generally performed at the monitor level • Average “across” the calendar quarter … month non-specific. • Each 24-hour average concentration essentially gets weighted the same in the quarterly mean … e.g., 1/16th in this example. • Quarterly means are rounded to one (1) decimal place. • A quarterly mean of 1.6 µg/m3 exceeds/violates the NAAQS; a quarterly mean of 1.5 µg/m3 does not

  10. Calculating 3-Month Averages: New (2008) Pb NAAQS • Calculations performed at the site-parameter level … collocated same-parameter monitor data combined using designated “primary” monitor as the primary data source and augmenting with data from the collocated (secondary) monitor(s) • Average first by month … get 3 monthly means … monthly means are not rounded • Then, average 3 monthly means to get a 3-month mean • Some 24-hour average concentration could be weighted higher in the 3-month mean … e.g., Jan and March daily averages count 1/18th (1/6 * 3) and Feb daily averages count 1/12th (1/4 * 3) • 3-month means are rounded to 2 decimal places. • A 3-month mean of 0.16 µg/m3 exceeds/violates the NAAQS; a 3-month mean of 0.15 µg/m3 does not

  11. Calculating 3-Month Averages: New (2008) Pb NAAQS Special Situation – Lots of Extra Samples in a Month • When the number of extra samples in a month exceeds the number of creditable samples (successfully completed scheduled samples plus make-up samples), the EPA Administrator has the discretion to calculate means using an alternative method • Why would a State do this? • To sample during an episode to gain knowledge • To sample during low periods to lower means • The alternative calculation method averages samples within a month by stratum before averaging across the month • A stratum is from a scheduled day until the next • Extra days occurring before the first scheduled sample in the month are included in the month’s last strata • The monthly average is treated the same as any other monthly average

  12. Determining Design Values and Validity: Old (1978) Pb NAAQS Quarterly means in 2-year period Sorted by descending quarterly mean concentration Example assume all 8 quarters are valid/complete • A “design value” is the metric compared to the NAAQS • The 2-year monitor-level Design Value (DV) was the highest (first maximum) valid/complete quarterly mean concentration over those two years. • Quarterly means were considered valid/complete if data capture was at least 75%. • The 2-year monitor-level DV was considered valid/complete if either: • All 8 quarterly means over the 2-year period were valid/complete Or • The highest valid/complete quarterly mean exceeded the NAAQS (1.5 µg/m3) … even if it was the only valid/complete quarter of the 8 possible.

  13. Determining Design Values and Validity: New (2008) Pb NAAQS Sorted by descending 3-month mean concentration • The 3-year site-level Design Value (DV) is the highest (first max) valid/complete 3-month concentration over those three years. • 3-month means are considered valid/complete if average data capture (avg. of 3 monthly data capture rates) is at least 75% … or, the 3-month period passes a “data substitution” test. • The 3-year site-level DV is considered valid/complete if either: • All 36 3-month means over the 3-year period are valid/complete Or • The highest valid/complete 3-monthy mean exceeds the NAAQS (0.15 µg/m3) … even if it is the only valid/complete 3-month period of the 36 possible

  14. Creditable number of samples Determining Design Values and Validity: New (2008) Pb NAAQS More Details on Data Completeness • 3-month means are considered valid/complete if average data capture (avg. of 3 monthly data capture rates) is at least 75% … or, the 3-month period passes a “data substitution” test. • Monthly data capture rate calculated as … (number of completed/successful scheduled samples in the month + number of “make-up” samples made for missed/voided scheduled samples in the month) / number of scheduled samples in the month • If a reported sample was not scheduled nor used as a make-up it is considered, “extra” • Make-up samples are either taken before the next required sampling day or exactly one week after the missed/voided sampling day. Make-up samples can span months but not years … For example a missed sample on January 31 may be made up on February 1, 2, 3, 4, 5, or 7 (with an assumed sampling frequency of every 6th day). If a scheduled sample for December is missed/voided, it can not be made up in January. • Make-up samples taken in the month after the one in which the miss/void occurred will be credited for data capture in the month of the miss/void but will be included in the month actually taken when computing monthly means. For example, if a make-up sample was taken in February to replace a missed sample scheduled for January, the make-up concentration would be included in the February monthly mean but the sample credited in the January data capture rate. • Monthly data capture rates are not rounded • 3-month average capture rates (i.e., average of three monthly data capture rates) are rounded to zero decimals (when expressed as a percent).

  15. Determining Design Values and Validity: New (2008) Pb NAAQS More Details on Data Completeness • 3-month means are considered valid/complete if average data capture (avg. of 3 monthly data capture rates) is at least 75% … or, the 3-month period passes a “data substitution” test. • A 3-month mean that does not have at least 75 percent data capture shall still be considered valid (and complete) if it passes either of the two following “data substitution” tests, one such test for validating an above NAAQS-level (i.e., violating) 3-month mean, and the second test for validating a below-NAAQS level 3-month mean. Both tests are merely diagnostic in nature intending to confirm that there is a very high likelihood if not certainty that the original mean (the one with less than 75% data capture) reflects the true over / under NAAQS-level status for that 3-month period; the result of one of these data substitution tests (i.e., a “test mean” is not considered the actual 3-month mean and shall not be used in the determination of design values. • The “above NAAQS level” test is as follows: Data substitution will be done in each month of the 3-month period that has less than 75 percent data capture. If by substituting the lowest reported daily value for that month (year non-specific; e.g., for January) over the 38-month design value period in question for missing scheduled data in the deficient months (substituting only enough to meet the 75 percent data capture minimum), the computation yields a recalculated test 3-month parameter mean concentration above the level of the standard, then the 3-month period is deemed to have passed the diagnostic test and the level of the standard is deemed to have been exceeded in that 3-month period.

  16. Determining Design Values and Validity: New (2008) Pb NAAQS More Details on Data Completeness • 3-month means are considered valid/complete if average data capture (avg. of 3 monthly data capture rates) is at least 75% … or, the 3-month period passes a “data substitution” test. • The “below NAAQS level” test is as follows: Data substitution will be performed for each month of the 3-month period that has less than 75 percent but at least 50 percent data capture; if any month has less than 50% data capture then the 3-month mean can not utilize this substitution test.. A 3-month Pb-TSP mean with less than 75% data capture shall still be considered valid (and complete) if, by substituting the highest reported daily value, month-specific, over the 3-year design value period in question, for all missing scheduled data in the deficient months (i.e., bringing the data capture rate up to 100%), the computation yields a recalculated 3-month parameter mean concentration equal or less than the level of the standard (0.15 µg/m3), then the 3-month mean is deemed to have passed the diagnostic test and the level of the standard is deemed not to have been exceeded in that 3-month period (for that parameter).

  17. Use of Pb-PM10 Data to Show Violations of the New Pb NAAQS • Pb-PM10 data collected via EPA protocols will be used to identify violations of the Pb NAAQS • Even if Pb-PM10 monitoring is voluntary at the site • Pb-PM10 data can not be used to show that the Pb NAAQS is met • Pb-PM10 are processed at face value (i.e., at reported concentrations) without adjustment when computing means and making comparisons to the NAAQS • If Pb-TSP and Pb-PM10 are both collected at a site, they are processed separately when calculating means • Thus, at a single site location, there could be two 3-month means for the same period, one for Pb-TSP and one for Pb-PM10. These are called “parameter means”. • A Pb-PM10 3-month parameter mean will only be considered the official “site mean” for that 3-month period if it shows a violation and either is greater than a (collocated) 3-month Pb-TSP mean or a valid 3-month Pb-TSP does not exist • If a 3-month Pb-PM10 mean is deemed the site-level 3-month mean, the site has definitely violated any 3-year period encompassing that 3-month one … but the corresponding design value could possibly be higher and also collected as Pb-TSP (i.e., when the mean for a different 3-month period is greater)

  18. Who Will Calculate Design Values? • OAQPS will calculate and disseminate Pb Design Values • Design Values will be posted on Air Trends website (epa.gov/airtrends) • 2005-2007 design values (for the new NAAQS) will be posted soon • 2006-2008 design values will be posted in August 2009; preliminary versions distributed in advance • Regions and States are encouraged to calculate their own design values and review/comment on OAQPS results

  19. Summary • Data handling for new NAAQS specified in 40 CFR Pt. 50, Appendix R • Get copy from TTN or e-CFR • New NAAQS based on Pb-TSP but Pb-PM10 exceedances/violations also count • New NAAQS is based on the highest “rolling” 3-month average over a 3-year period • 36 averaging periods, the first 2 including months from the previous year • Months are averaged first, and then (3) monthly means are averaged to obtain a 3-month mean • Alternative calculation method can be used when there are more extra samples in a month than creditable samples • A 3-month period is valid if it has 75% or more data capture or if it passes a diagnostic data substitution test • 36 valid 3-month periods are needed to show that the NAAQS was met but only one 3-month period needed to show a violation • OAQPS will calculate and post Design Values • Call me if you have questions: Mark Schmidt – (919) 541-2416

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