Ozone Monitoring Issues & Opportunities - II

Ozone Transport Commission MANE-VU Fall Meeting

November 19, 2014Crystal City, VA

Will Ollison1220 L Street, NW • Washington, DC 20005-4070 • www.api.org

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Recommendations

• EPA should allow elevation adjustments to O3 design values (DVs) to account for population dose, as they presently do for PM DVs, to reduce over-regulation of elevated (> 1000 feet) locations

• Similarly, EPA should allow inlet height DV adjustments to 2 meters, within the 2-15 meter inlet height limit, to account for typical outdoor breathing zone heights

• EPA should facilitate NO-scrubber upgrades of the existing compliance UV monitor network to reduce network positive interference bias

1220 L Street, NW • Washington, DC 20005-4070 • www.api.org

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Compliance with PM NAAQS

PM2.5/10 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.

1220 L Street, NW • Washington, DC 20005-4070 • www.api.org

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O3 Risk Assessment (EPA-452/R-14-004, August 2014) “The controlled human exposure studies drawn

upon for this lung function risk assessment were conducted at low altitudes (< 600 feet). It is not known whether it is more appropriate to use a mass concentration (µg/m³) or a mixing ratio concentration (ppm) at higher altitudes where the barometric pressure is lower…if in fact mass concentrations are the appropriate exposure metric, then the lung function responses in a high-altitude city such as Denver (5300 feet) could be overestimated by about 15%.” (p. 6-8)

1220 L Street, NW • Washington, DC 20005-4070 • www.api.org

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High Elevation O3 Monitors ( > 1000 feet)

● ● 14,100 ft14,100 ft

DV cut 28 ppbDV cut 28 ppb

● ● 9000-12,000 ft 9000-12,000 ft

DV cut 20-24 ppbDV cut 20-24 ppb

●● 6300-9000 ft6300-9000 ft

DV cut 15-19 ppbDV cut 15-19 ppb

● ● 3900-6300 ft3900-6300 ft

DV cut 10-14 ppbDV cut 10-14 ppb

● ● 1700-3900 ft1700-3900 ft

DV cut 5-9 ppbDV cut 5-9 ppb

● ● 1000-1700 ft1000-1700 ft

DV cut 2-4 ppbDV cut 2-4 ppb

1220 L Street, NW • Washington, DC 20005-4070 • www.api.org

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40 CFR Part 58, Appendix E to Part 58 – O3 Inlet Height“The probe…must be located between

2 and 15 meters above ground level for all O3…monitoring sites …at least 1 meter vertically or horizontally away from any supporting structure, walls, etc…[and] located on the [prevailing] windward side of the building during the season of highest concentration potential for the pollutant being measured.”

1220 L Street, NW • Washington, DC 20005-4070 • www.api.org

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O3 Monitor Inlet Heights Above Grade

1220 L Street, NW • Washington, DC 20005-4070 • www.api.org

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Quarterly O3 Gradient by Monitor Inlet Height AGL(m)

1220 L Street, NW • Washington, DC 20005-4070 • www.api.org

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Altitude/Inlet Height-Estimated 75 ppb/2 meter Equivalent DVsAltitude >

MSL (m)Altitude Adj. Eqv. DV (ppb)

Inlet Height AGL (m)

Inlet Height Eqv. DV (ppb)

0 75 2 75110 76 3 76220 77 4 78340 78 5 79460 79 6 80580 80 7 81700 81 8 82830 82 9 83960 83 10 841100 84 11 851200 85 12 861350 86 13 871500 87 14 881650 88 15 89

1220 L Street, NW • Washington, DC 20005-4070 • www.api.org

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