UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION III 1650 Arch Street Philadelphia, Pennsylvania 19103


### DATE: JAN 4 2011 SUBJECT: Technical Support DocumentRegarding Ozone Monitoring Data—Pennsylvania; Clean Data Determinationforthe Pittsburgh-BeaverValley 8-Hour Ozone NonattainmentArea ?41 .-4

P

. FROM: MariaA. Pino, Air Quality Planning Specialist Office ofAir Program Planning TO: File THRU: 

### MarilñPbwers, Acting Associate Director Office’’fAir Program Planning
This documentprovides atechnical review ofthe air quality monitoring dataused to supportthe Environmental Protection Agency’s (EPA’s) proposed determinationthatthe Pittsburgh-Beaver Valley 8-hour ozone nonattainment area (the Pittsburgh Area) has attained the 1997 ozone national ambient air quality standard (NAAQS). A. BACKGROUND The Pittsburgh Area includes Allegheny, Armstrong, Beaver, Butler, Fayette, Washington, and Westmoreland Counties in Pennsylvania. The Pittsburgh Area is classified as a subpart 1 nonattainment area forthe 1997 8-hour ozone NAAQS. See 40 CFR 81.339.
B. EVALUATION OF AIR QUALITY MONITORING DATA I. DataRequirements The criteria for determining ifan areais attaining the 1997 8-hour ozone NAAQS are set out in 40 CFR 50.10 and appendix I. The determination is based onthe mostrecentthree complete, consecutive calendaryears ofquality-assured air quality monitoring data at all ozone monitoring sites in the area. To attain this standard, the annual fourth-high daily maximum 8-hour ozone concentrations measured at each monitor

### and averaged overthe three-yearperiod (the monitoring site’s ozone design value) mustnot exceedthe ozone standard. The level ofthe 1997 8-hourNAAQS for ozone is 0.08 parts permillion (ppm). Based on an ozone datarounding convention described in 40 CFRpart 50, appendix I, the 8-hour standard is met ifozone design value is 0.084 ppm (84 ppb) or lower. Whenthe design value is less than or equal to 0.084 ppm at each monitoring site withinthe 

### area, the areameets the NAAQS.The datamustbe collected and quality-assuredin accordance with 40 CFRpart 58, and must be recorded in EPA’s Air Quality System (AQS). The data supporting attainment ofthe standard mustbe complete in accordance with40 CFRpart 50, appendix I. The data completeness requirement is metwhenthe average percent ofdays with valid ambient monitoring data is greaterthan 90%, and no single yearhas less than 75% data completeness. Forthe Pittsburgh Area, the ozone season extends fromthe beginning ofApril through the end of October. A complete ozone season consists of214 monitoring days.
II. Certified Air Quality Monitoring Data, 2007

- 2009 The Commonwealth ofPennsylvania submitted complete, quality assured air quality monitoring data into AQS, and EPA concurred on Pennsylvania’s data. Attached is the AQS report containing 8-hour ozone data forthe Pittsburgh Areaforthe 2007 to 2009 ozone monitoring seasons. Table 1, below, summarizes the data found in thatreport As shown in Table 1, all 2007-2009 8-hour ozone design values forthe Pittsburgh Area are 0.084 ppm or less. In addition, all monitors meetthe completeness requirements ofan average percent ofdays with valid ambientmonitoring data greaterthan 90%, and no single yearhas less than 75%. Therefore, the Pittsburgh Areameets the 1997 8-hour ozone NAAQS, considering 2007- 2009 data. Table 1: 2007-2009 Pittsburgh Area 8-Hour Ozone Design Values & Data Completeness 4th Highest Value Percent Completeness (ppm) 2007-2009 (valid monitored days I required DesF’n days) County Site ID Value 2007- 2007 2008 2009 (ppm) 2007 2008 2009 2009 average Allegheny 420030008 0.083 0.079 0.069 0.077 99 100 98 99 Allegheny 420030010 0.081 0.074 0.067 0.074 100 97 99 99 Allegheny 420030067 0.077 0.075 0.069 0.073 94 99 100 98 Allegheny 420031005 0.086 0.085 0.077 0.082 94 100 98 97 Armstrong 420050001 0.083 0.078 0.071 0.077 100 100 100 100 Beaver 420070002 0.080 0.073 0.066 0.073 96 97 97 97 Beaver 420070005 0.072 0.075 0.068 0.071 99 95 97 97 Beaver 420070014 0.077 0.074 0.068 0.073 100 100 100 100 Washington 421250005 0.077 0.071 0.068 0.072 99 99 100 99 Washington 421250200 0.073 0.069 0.063 0.068 100 100 99 100 Washington 421255001 0.075 0.077 0.065 0.072 100 89 97 95 Westmoreland 421290006 0.079 0.072 0.064 0.071 100 100 100 100 Westmoreland 421290008 0.077 0.075 0.065 0.072 99 100 97 99

2III. Preliminary Air Quality Monitoring Data, 2010 According to 40 CFR Part 58, states are required to submit air quality monitoring data for each calendar quarter no laterthan 90 days afterthe end ofthe quarter. Forthe fourth quarter ofthe year, October 1 through December 31, states are requiredto submit data into AQS by the end of March the following year. Thus, Pennsylvaniahas until March 2011 to submit ozone monitoring data for October 2010 into AQS. However, Pennsylvania submitted its October 2010 monitoring data early. The attached AQS report contains 8-hour ozone data forthe Pittsburgh Areaforthe entire 2010 ozone monitoring season. Also according to 40 CFR Part 58, by May 1 ofeach year, states are required to submit to EPA an “annual airmonitoring data certification letter” to certify thatthe previous year ofambient concentration and quality assurance data are completely submittedto AQS and are accurate. For 2010 data, Pennsylvaniais required to submitthe certification letterby May 1, 2011. Until Pennsylvania certifies its 2010 data, EPA will consider it “preliminary.” As shown in Table 2, all preliminary 2008-20 10 8-hour ozone design values forthe Pittsburgh Area are 0.084 ppm or less. In addition, all monitors meetthe completeness requirements ofan average percent ofdays with valid ambient monitoring data greaterthan 90%, and no single year has less than 75%. Therefore, preliminary data indicates thatthe Pittsburgh Area continues to meet the 1997 8-hour ozone NAAQS, considering 2008-2010 data. Table 2: Preliminary 2008-2010 Pittsburgh Area 8-Hour Ozone Design Values & Data

Completeness -- ________________ ____________ ___________________________

County Site ID 4th Highest Value (ppm)
2008 2009 2010* Preliminary 2008-2010

Design Value (ppm) Percent Completeness (valid monitored days /required days) 2008 2009 2010* 2008-2010 _______

average” Allegheny 420030008 0.079 0.069 0.080

. Allegheny 420030010 0.074 0.067 0.074

— Allegheny 420030067 0.075 0.069 0.078

— Allegheny 420031005 0.085 0.077 0.083 Armstrong 420050001 0.078 0.071 0.079

— Beaver 420070002 0.073 0.066 0.075

— Beaver 420070005 0.075 0.068 0.077 C Beaver 420070014 0.074 0.068 0.073 0 100 98 96. 97 99 92 99 100 98 100 98 99 100 100 100

97 97 97 95 97 97 Washington 421250005 0.071 0.068 0.072 98 96

96 95 0 070 100 100 86 Washington 421250200 0.069 0.063 0.073 0.068 100 99 99 99 Washington 421255001 0.077 0.065 0.071 0.071 89 97 97 94 Westmoreland 421290006 0.072 0.064 0.070 0.069 100 100 98 99 Westmoreland 421290008 0.075 0.065 0.076 0.072 100 97 97 98 99 100 99 99

Note: The asterisk (*) signifies preliminary values.

3Attachments:

- EPA AQS Quick LookReport (AMP45O), dated December 28, 2010, containing 2007- 2009 ozone airquality data for Pittsburgh Area.

- EPA AQS QuickLook Report (AMP45O), dated December28, 2010, containing preliminary 2010 ozone air quality data forPittsburgh Area.

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