DC Circuit upholds EPA sulfur and soot pollution standards

A D.C. Circuit panel rejected a Center for Biological Diversity challenge to EPA air quality standards for nitrogen, sulfur and soot, ruling the agency reasonably found the changes would have no effect on endangered species like the Shenandoah salamander and bay checkerspot butterfly. The EPA's December 2024 rule tightened the sulfur dioxide standard to 10 parts per billion while leaving nitrogen oxide and particulate matter standards from a 2011-2012 review untouched.

Chief Judge Sri Srinivasan, an Obama appointee joined by Trump appointee Neomi Rao, found the EPA's analysis showed all but two monitoring sites nationwide already met the new sulfur standard, so no areas would face new emissions reduction requirements. The Center for Biological Diversity argued the agency ignored cumulative and ongoing harms from the pollutants and relied on outdated science; Judge Karen Henderson concurred separately, calling the EPA's inaction outside the Endangered Species Act's consultation trigger entirely.

The full dispatch is available from the source below.