1. NAAQS Altitude Effects Ozone Transport Commission Annual Meeting June 11, 2014 Baltimore, MD Will Ollison 1220 L Street, NW Washington, DC 20005-4070 www.api.org1

2. Compliance with PM NAAQS PM 2.5/10 compliance addresses altitude effects. 40 CFR Part 50, Appendix L, Section 2.2: Each filter is weighed…before and after sample collection to determine the net gain due to collected PM2.5. The total volume of air sampled is determined by the sampler from the measured flow rate at actual ambient temperature and pressure and the sampling time. The mass concentration of PM2.5 in the ambient air is computed as the total mass of collected particles in the PM2.5 size range divided by the actual volume of air sampled, and is expressed in micrograms per cubic meter of air. 40 CFR Part 50, Appendix J, Section 2.2: …For PM10 samples collected at temperatures and pressures significantly different from EPA reference [25°C, 1 atm] conditions, these corrected concentrations sometimes differ substantially from actual concentrations,…particularly at high elevations. Although not required, the actual PM10 concentration can be calculated from the corrected concentration, using the average ambient temperature and barometric pressure during the sampling period. 1220 L Street, NW Washington, DC 20005-4070 www.api.org 2

3. Compliance with O 3 NAAQS O 3 compliance does not address altitude effects. 40 CFR Part 50 Appendix P, Section 2.2: The standard-related summary statistic is the annual fourth-highest daily maximum 8-hour O 3 concentration, expressed in parts per million, averaged over three years. The 3-year average shall be computed using the three most recent, consecutive calendar years of monitoring data meeting the data completeness requirements described in this appendix. The computed 3-year average of the annual fourth-highest daily maximum 8-hour average O 3 concentrations shall be reported to three decimal places (the digits to the right of the third decimal place are truncated, consistent with the data handling procedures for the reported data). O 3 photometers calculate and report parts per million mixing ratios from measured actual concentrations at absorption tube temperatures and pressures. These mixing ratio O 3 compliance metrics are pressure invariant and do not change with altitude. At a given O 3 ppm level and breathing rate less O 3 mass is inhaled at higher altitudes, penalizing highlanders into complying with lower effective NAAQS than lowlanders. 1220 L Street, NW Washington, DC 20005-4070 www.api.org3

4. OTC State 2010-2012 Design Values - Monitors > 1000 feet State Height (feet) < 75 ppb< 70 ppb< 65 ppb< 60 ppbMonitor Alt Adj < 75 ppb Alt Adj < 70 ppb Alt Adj < 65 ppb Alt Adj < 60 ppb CT1519 YESNO 090050005 YES NO ME1507 230090102 MD2356 240230002 MA3482 250034002 MA1006 250154002 NH6233 330074001 NH1386 330074002 NH2286 330115001 NY1063 360130011 NY1939 360310003 NY1693 360410005 NY1764 360430005 NY1534 360830004 NY1603 361010003 NY1941 361111005 VT1325 500070007 VA3526 511130003 VA1106 511611004 VA1282 511650003 VA2466 511970002 1220 L Street, NW Washington, DC 20005-4070 www.api.org4

5. OTC State 2010-2012 Design Values - Monitors > 1000 feet State Height (feet) < 75 ppb< 70 ppb< 65 ppb< 60 ppbMonitor Alt Adj < 75 ppb Alt Adj < 70 ppb Alt Adj < 65 ppb Alt Adj < 60 ppb PA1261NO 420030067YESNO PA1145 420050001 PA1334 420070002 PA1216 420070005 PA1132 420130801 PA1174 420210011 PA1168 420270100 PA2129 420334000 PA2018 420550001 PA1403 420590002 PA1900 420630004 PA1095 420850100 PA1301 420890002 PA2244 421174000 PA1158 421250200 PA1126 421255001 PA1188 421290008 1220 L Street, NW Washington, DC 20005-4070 www.api.org5

6. Recommendations Since EPA will use high elevation rural/remote CASTNet O 3 monitor design values for 2011-2013 NAAQS compliance determinations, and Since CASAC will recommend EPA reduce the 75 ppb O 3 NAAQS into the 60-70 ppb mixing ratio range, and Since CASAC-AMMS will recommend a new interference-free O 3 Federal Reference Method, OTC States should (1) request that EPA expedite upgrades of existing OTC network O 3 monitors to interference-free status and (2) account for altitude effects in any revised mixing ratio O 3 NAAQS. Request that EPA to account for altitude effects in gaseous NAAQS 1220 L Street, NW Washington, DC 20005-4070 www.api.org6