Supreme Court Declines to Hear Appeal of NO2 Standard


The U.S. Supreme Court has declined, without comment, to review a DC Circuit Court of Appeals decision to uphold EPA’s air quality standard for nitrogen dioxide (NO2). American Petroleum Institute v. EPA, U.S., No. 12-760, 4/1/13.

EPA’s 2010 final rule set a one-hour standard of 100 parts per billion (ppb) to protect against short-term NO2 exposures and retained the existing annual standard of 53 ppb to protect against long-term exposures.

Mobile sources (conventionally-fueled vehicles) are the largest source of NO2 emissions, followed by fuel combustion and other industrial sources. NO2 contributes to the formation of ozone and fine particulate matter.  According to EPA, NO2 exposure has been linked to respiratory problems.