EPA Releases First External Review Draft of New ISA of NOx for Public Comment and Peer Review

31 August 2007

The US Environmental Protection Agency (EPA) released for public comment and independent expert peer review its first external review draft of the new Integrated Science Assessment for Oxides of Nitrogen—Health Criteria.

Oxides of nitrogen is one of six principal (criteria) pollutants for which EPA has established national ambient air quality standards (NAAQS). The Clean Air Act requires EPA to periodically review the scientific basis for standards by preparing an Integrated Science Assessment (ISA), formerly called an Air Quality Criteria Document (AQCD). The basis for NO_x standards was last reviewed in 1996.

The draft ISA—Health Criteria was prepared as part of the review of the primary or human health-based NAAQS for oxides of nitrogen. This represents EPA’s latest evaluation of the scientific literature on the potential adverse health effects resulting from exposures to oxides of nitrogen, particularly nitrogen dioxide or NO₂.

There are significant new data, particularly epidemiological studies, that strengthen the evidence for these adverse effects since the last scientific review document was released in 1993.

The current review is the first using the agency’s revised process for reviewing and setting NAAQS. A review of the secondary NAAQS (based on ecological or welfare effects) for oxides of nitrogen is being conducted independently, in conjunction with a review of the secondary NAAQS for sulfur oxides.

The first draft ISA will be reviewed by the Clean Air Scientific Advisory Committee (CASAC) at a public meeting later this year. A second draft ISA will be released in 2008, which will address CASAC and public comments received on the first draft ISA. Once final, the complete ISA will provide the scientific bases for EPA’s periodic review and possible revision of the primary NAAQS for oxides of nitrogen.

The current draft of the ISA concludes that it is plausible, consistent, and coherent that current ambient NO₂ exposures directly result in adverse impacts to public health at concentrations below the current NAAQS for NO₂.

The deadline for comments is 31 Oct 2007.

Resources:

• Integrated Science Assessment for Oxides of Nitrogen—Health Criteria (First External Review Draft)

• Annexes for the Integrated Science Assessment for Oxides of Nitrogen—Health Criteria (First External Review Draft)