On June 29, EPA indicated its intent to propose a new one-hour air quality standard for NO2 while retaining the existing annual standard for the pollutant and expanding its monitoring network. EPA's proposed rule, which has not yet been published in the Federal Register, would create a new primary one-hour national ambient air quality standard for NO2 at a level between 0.080 parts per million and 0.10 ppm. The agency proposed retaining the current annual primary standard of 0.053 ppm, which is an annual average. Currently, the secondary annual standard is also set at 0.053 ppm and all areas of the country currently meet the existing primary annual air quality standard, according to EPA.
The primary air quality standard is set to protect public health while the secondary standard protects public welfare and the environment. "We're updating these standards to build on the latest scientific data and meet changing health protection needs" said EPA Administrator Lisa Jackson in a statement. "In addition to limiting annual average concentrations, we're preventing high NO2 levels for shorter periods of time and adding stronger monitoring in areas near roadways, where the highest levels of NO2 are often found. This will fill gaps in the current standard and provide important additional protections where they are needed most."
The proposed rule would also require NO2 monitoring along major roads in cities with at least 350,000 residents and continued monitoring in cities with more than 1 million people.
EPA will accept public comment on the proposal for 60 days after it is published in the Federal Register and public hearing will be held in Los Angeles and Washington, D.C., in August.