Health Effects Of NO₂ Reviewed

Nitrogen dioxide causes adverse respiratory effects in people at exposure levels below the current federal air quality limit for this pollutant, EPA concludes in a draft report. The draft analysis, released Aug. 30, examines scientific studies on the potential health effects of exposure to oxides of nitrogen, particularly NO₂, which are products of combustion.

The draft says "it is plausible, consistent, and coherent" that exposure to NO₂ at levels that are lower than the current air quality standard can "result in adverse impacts to public health." The document is designed to help agency policymakers decide whether to tighten the national ambient air quality standard for NO_x, which is 53 ppb. The agency last conducted a review of scientific studies about NO_x in 1993.

The draft report is EPA's first analysis of a health-based air quality standard conducted via a controversial new process implemented by the Bush Administration that integrates policy considerations with scientific data. Critics say the new process increases political sway over air quality decisions while decreasing the role of agency scientists (C&EN, Dec. 18, 2006, page 15). The agency's Clean Air Scientific Advisory Committee will review the draft analysis later this year.

The draft document is available at cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=181712.