The Pennsylvania Department of Environmental Protection (PADEP) oversees the Emission Reduction Credit (ERC) Registry System. The EPA has designated Allegheny Armstrong, Beaver, Berks, Butler, Carbon, Fayette, Lehigh, Northampton, Lancaster, Bucks, Chester, Delaware, Montgomery, Philadelphia, Washington, and Westmorland Counties as marginal nonattainment zones for ozone. Additionally, Allegheny, Delaware and Lebanon are classified as moderate nonattainment for PM2.5, and Allegheny only is classified as moderate maintenance for PM10.
ERCs generated in the five Philadelphia counties of Bucks, Chester, Delaware, Montgomery and Philadelphia may transferred to users in the five-county areas with some limitations. In the remainder of the state ERC may be transferred anywhere in the state except the five-county Philadelphia area.
In Pennsylvania stationary sources must obtain ERCs to satisfy the offset ratio requirements for the proposed emissions increase. Sources must obtain ERCs if they emit more than:
- 100 tons/year of CO,
- 25 tons/year of NOx,
- 25 tons/year VOC,
- 100 tons/year SOx,
- 100 tons/year of PM10, and/or
- 100 tons/year of PM2.5.
In Pennsylvania the current offset ratio for marginal nonattainment areas is 1.1 tons of ERCs to each new ton of emissions. For areas of moderate nonattainment, the offset ratio is 1.15 tons of ERCs to each new ton of emissions.