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Environmental Assessment

Integrated Science Assessment for Oxides of Nitrogen – Health Criteria (Final Report, 2008)


EPA has released the final report, 2008 Integrated Science Assessment for Oxides of Nitrogen - Health Criteria and the Annexes, as announced in the July 11, 2008 Federal Register Notice.

Report Information

The Integrated Science Assessment (ISA) for Oxides of Nitrogen – Health Criteria document represents a concise synthesis and evaluation of the most policy-relevant science and will ultimately provide the scientific bases for EPA’s decision regarding whether the current standard for NO2 sufficiently protects public health.

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Dennis J. Kotchmar
  • by phone at:   919-541-4158
  • by fax at:   919-541-1818
  • by email at:  kotchmar.dennis@epa.gov


Cover of the NOx ISA 2008 Report Oxides of nitrogen is one of six principal (or 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 these standards by preparing an Integrated Science Assessment (ISA), formerly called an Air Quality Criteria Document (AQCD). The ISA was prepared as part of the review of the primary or human health-based NAAQS for oxides of nitrogen. The Final NO2 ISA evaluates and integrates the newly available health evidence, and contains the key information and judgments formerly found in the AQCD. A series of Annexes to the draft ISA provides more extensive and detailed summaries of the most pertinent scientific literature. This is 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 effects since the last scientific review document was released in 1993.


1982EPA released the document Air Quality Criteria for Oxides of Nitrogen.
Aug 1991EPA release an external review draft of the Air Quality Criteria for Oxides of Nitrogen for public review and comment.
Aug 1993EPA released the final report on the Air Quality Criteria Document for Oxides of Nitrogen.
Dec 2005EPA published a Call for Information on Oxides of Nitrogen in the December 9, 2005 Federal Register Notice.
Feb 2007EPA hosted a workshop on the assessment of health science for the review of the NAAQS for Nitrogen (NOx) and Sulfur Oxides (SOx).
Aug 2007EPA releases the First External Review Draft for an External Peer Review and public comment.
Oct 2007EPA hosts a Science Advisory Board (SAB) CASAC Meeting and external peer review to review and discuss the draft report.
Mar 2008EPA releases the Second External Review Draft for external review and public comment.
Jul 2008EPA releases the final ISA.

Next Steps

The ISA provides the scientific bases for EPA’s periodic review and possible revision of the primary NAAQS for oxides of nitrogen. For further information on this review, go to http://www.epa.gov/ttn/naaqs/standards/nox/s_nox_index.html


U.S. EPA. Integrated Science Assessment for Oxides of Nitrogen – Health Criteria (Final Report, 2008). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-08/071, 2008.


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