The state of Delaware on Nov. 5 challenged the U.S. Environmental Protection Agency's denial of its claims that emissions from upwind power plants are preventing it from meeting national ozone standards.
Limits for ozone and a number of other harmful pollutants that can cause illnesses are set under the National Ambient Air Quality Standards, or NAAQS. Ozone is formed in the atmosphere through a reaction between nitrogen oxides and volatile organic compounds emitted from sources such as cars, power plants, refineries and chemical plants. The EPA in 2008 established a requirement for states to meet a 75-parts-per-billion ozone standard and in 2015 lowered that standard to 70 ppb.
The EPA on Sept. 14 denied separate petitions from the Delaware Department of Natural Resources and Environmental Control filed against four power plants in West Virginia and Pennsylvania over their release of NOx. That same day, the EPA also denied a petition from the Maryland Department of the Environment claiming that NOx emissions from generators across Indiana, Kentucky, Ohio, Pennsylvania and West Virginia were preventing the state from meeting the EPA's ozone standards.
Often referred to as the "good neighbor" provision of the Clean Air Act, Section 126(b) allows a state to petition the EPA to take action against power plants outside its borders whose emissions interfere with its ability to meet the NAAQS. However, the EPA in its September decision said it found that the identified sources in Delaware's and Maryland's petitions do not, and are not expected to, emit pollution in violation of the good neighbor provision for either the 2008 or 2015 ozone standards.
Maryland and a coalition of environmental groups in October filed petitions for judicial review in the D.C. Circuit that have been consolidated in State of Maryland v. EPA (No. 18-1285). The Delaware D.C. Circuit case is Delaware Department of Natural Resources and Environmental Control v. EPA (No. 18-1301).
