### ATTACHMENT A AIR QUALITY IN THE DI STRICT OF COLUMBIA

1) District of Columbia’s Ambient Air Monitoring Network

District Department of the Environment’s Air Quality Division (AQD) operates and maintains the ambient air quality monitoring network for the District as mandated by the federal Clean Air Act. The network consists of five air monitoring stations. Ambient measurements are made for all criteria air pollutants, urban air toxics, and various pollutant s including ground-level ozone and fine particulate matter (PM 2.5 ) precursor compounds. Of the five stations in the District, three stations measure groundlevel ozone (ozone) and report air quality levels every hour. Figure 1 below shows the ambient ozone network on a DC map, and the Table 1 gives the monitor type and re lated information for the ozone measurement stations.

Table 1: District of Columbia’s Ground-level Ozone Air Quality Monitoring Stations
Site Name Site ID Address Monitor Type

Takoma Park 11-001-0025 Dahlia St. & Piney Branch Road N.W. NAMS/ SLAMS NAMS/ SLAMS

River Terrace 11-001-0041 34 th & Dix Streets, N.E. SLAMS

McMillan Reservoir 11-001-0043 2500 First Street, N.W PAMS Type 2 Air Quality Index National Air Toxics Trends PM 25 Chemical Speciation Network (CSN) NCore Network (candidate site)

Figure 1: District of Columbia’s Ground- level Ozone Air Quality Monitoring Network

Monitored air quality data from these three stations are used to track the District’s progress towards achieving its air quality goals for meeting the nati onal ambient air quality standards (NAAQS) and for verifying attainment status for ozone. Takoma School 11-001-0025 McMillan 11-001-0043

River Terrace 11-001-0041

A-12) Ozone Air Quality Design Concentrations

Presented below in Table 2 and Figure 2 are the design concentration values, in parts per million (ppm), for 8-hour ozone air quality for recent years from th e District’s ambient stations network. The design concentrations were determined by following EPA’s gui dance. Note that the data for calendar year 2008 are yet to be certified by the stat e air agency, and AQD will transmit offi cial certification to EPA Region III by the July 1, 2009 deadline.

Table 2: Ozone design value concentrat ions in the District of Columbia

2006 2007 2008* Takoma Park 11-001-0025 0.080 0.081 0.080

River Terrace 11-001-0041 0.079 0.085 0.086

McMillan Reservoir 11-001-0043 0.085 0.087 0.087

District of Columbia 0.085 0.087 0.087 *Data for calendar year 2008 are yet to be certified Design Concentration (ppm) Station Name/Id

The design concentrations at the District’s mon itoring stations varied between 0.079 ppm and 0.087 ppm during the evaluation period and recorded violati ons of the ozone 8-hour new NAAQS (0.075 ppm).

Figure 2: Ozone design value concentrati ons at District’s monitoring stations

0.045 0.055 0.065 0.075 0.085 0.095

2006 2007 2008*

YEAROzone Design Concentration (ppm)

Takoma Park 11-001-0025

River Terrace 11-001-0041

McMillan Reservoir 11-001-0043

Also, based on EPA’s guidance, the highest concentration value among th e three stations will determine the District’s design concentration for a given evaluation year. The 8- hour ozone design concentrations in the District for 2006, 2007 and 2008 are 0.085 pp m, 0.087 ppm, and 0.087 ppm, respectively. The District’s ozone design concentrations were in violation of the 0.075 ppm 8-hour NAAQS, and the level of violation in 2008 was 0.012 ppm above the ozone air quality standard.

A-23) Ozone Precursor Pollutant Emissions in the District and the Metropolitan Areas

Volatile organic compounds (VOCs) and nitrogen oxi des (NOx) are the primar y precursor pollutants that lead to ground-level oz one air quality issues during warmer mont hs of the year. Presented in Table 3 and Figure 3 below are the jurisdiction-level air pollution emissions for the metropolitan Washington, DC-MD-VA area for a typical summer day in 2002. The Metro area incl udes the District of Columbia; Charles, Calvert, Frederick, Montgomery and Prin ce George’s counties in Maryland; the cities of Bowie, College Park, Gaithersbur g, Greenbelt, Frederick, Rockville, and Takoma Park in suburban Maryland; and Arlington, Fairfax, Loudoun, Prince Willia m counties and the cities of Alexandria, Falls Church, Fairfax, Manassas, and Manassa s Park in northern Virginia.

Table 3: Pollution Emissions for Ozone Precurs ors in the Metropolitan Washington Area for 2002 (Data source: Washington DC-MD-VA Nonattainment Area’s Ground-level Ozone SIPs, May 23, 2007) Jurisdiction Volatile Organic Compounds (VOCs) Nitrogen Oxides (NOx) District of Columbia 39.1 41.3 Suburban Maryland 217.0 329.0

Northern Virginia 192.2 226.9 Metropolitan Area Total

Emissions (Tons/Day) 448.3 597.2

Being a non-industrial jurisdiction, Dist rict is home to a small number of sources that contribute to its ozone air quality problem and pr ecursor pollution emissions in the metropolitan area.

Figure 3: Pollution Emissions for Ozone Precursor s in the Metropolitan Wa shington Area in 2002 (Data source: Washington DC-MD-VA Nonattainment Area’s Ground-level Ozone SIPs, May 23, 2007)

48%

43% 9%

MD VA DC Metro Area's VOC Emissions: 448 tons/day

55% 38% 7%

MD VA DC Metro Area's NOx Emissions: 597 tons/day

The air pollution sources in th e metropolitan area emitted 448.3 tons/day VOCs and 597.2 tons/day NOx during the year 2002. Contribution from the District ’s sources was 39.1 tons of VOCs and 41.3 tons of NOx per day, which represents seven to nine pe rcent of the ozone precursor emissions in the Washington DC-MD-VA me tropolitan area.

The District has implemented strict er controls on its sources since th e early nineties and continues its pursuit to further reduce its contri bution. The District’s local cont rols include an inspection and maintenance program to curtail pollution from ve hicles, NOx budget programs on stationary point

A-3sources, and VOC controls for solvents, industria l and auto maintenance products, gasoline handling, and other diverse area sources. Table 4 below shows the projected air pollution emissions for 2009 for the metropolitan Washington, DC-MD-VA area for a typical summer day.

Table 4: Projected Emissions for Ozone Precurs ors in the Metropolitan Washington Area for 2009 (Data source: Washington DC-MD-VA Nonattainment Area’s Ground-level Ozone SIPs, May 23, 2007) Jurisdiction Volatile Organic Compounds (VOCs) Nitrogen Oxides (NOx) District of Columbia 31.5 27.6 Suburban Maryland 168.5 179.6

Northern Virginia 148.8 154.9 Metropolitan Area Total

Emissions (Tons/Day) 348.8 362.1

A comparison of the ozone precu rsor pollution emissions between 2002 and 2009 in the District indicates a 19% reduction in VOC emissions and a 33% drop in NOx emissions. Despite its significant efforts to reduce ozone precursor pollution from its so urces, the monitors in th e District did not show proportionate improvement in ambient air quality, and the District’s air monitors continue to record violations of the 8-hour ozone NAAQS.

Analyses by the Ozone Transport Commission (OTC) since the 1990s point to transported pollution as having a significant contribution for the ozone air quality in OTC member states in cluding the District. Mitigating pollution transport is critical for a non-i ndustrial urban jurisdiction with air quality issues such as the District. National efforts to impose a dditional controls on on-road and off-road mobile and disperse area sources an d stricter controls on large industrial sources and power plants to curtail transported pollution are needed to assist the District and other nona ttainment areas in the nation to achieve the new 8-hour ozone NAAQS.

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