EPA has classified Northern Virginia as as Marginal Nonattainment for Ozone under the 2008 and 2015 NAAQS Standard and includes Alexandria City, Arlington County, Fairfax County, Fairfax City, Falls Church City, Loudoun County, Manassas Park City, Manassas City, and Prince William County.
|Pollutant||New Major Source Emission Rates||Major Modification to existing Source|
|Nitrogen oxides (NOx)||>100 tons/year||>40 tons/year|
|Volitile Organic compounds (VOC)||>100 tons/year||>40 tons/year|
To satisfy offset requirements, new or modified major facilities in nonattainment areas must obtain ERCs to satisfy the offset ratio requirements for proposed emission increases. The offset ratio for marginal nonattainment area for ozone is 1.1 to 1. That means if 100 tpy of VOCs are emitted from a proposed new or modified major facility in the Northern Virginia nonattainment area, the facility must obtain 110 tpy of ERCs to offset the increase in VOC emissions.