Attainment of PM2.5 Standard

For the first time since the Allegheny County Health Department (ACHD) began monitoring fine particulate (PM2.5) pollution, Allegheny County is monitoring attainment of the current annual PM2.5 standard.

The annual PM2.5 SIP submitted by ACHD projected attainment within the Liberty-Clairton area by 2014. Recent monitoring, however, shows the Liberty monitor in attainment 3 years ahead of schedule. The Liberty monitor’s 2009-2011 PM2.5 design value is 15 ug/m3. Design values are statistics that describe the air quality status of a given area relative to the level of the National Ambient Air Quality Standards (NAAQS). In other words, they are averaged values that EPA uses to officially determine attainment or non-attainment of standards. The 15 ug/m3 design value at the Liberty monitor means the area is currently in attainment of the standard. With this, all of Allegheny County is in attainment of the current annual standard for the first time.

The early attainment is due in large part to local and regional controls of PM2.5 and the pollutant’s precursors. While 2009 was a low production year and emission levels from industry across the country were lower than normal, 2010 and 2011 were representative of normal production levels. Both years are included in the design value calculation, indicating a substantial decline in emissions despite normal production levels.

The new data is great news for residents of the Liberty-Clairton area, and suggests that substantial improvements are being made. The next critical issue is the PM2.5 24-Hour standard of 35ug/m3. Currently, all sites in Allegheny County except the Liberty monitor are in attainment. ACHD is projecting attainment at Liberty by 2014.