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Integrated Science Assessment (ISA) for Oxides of Nitrogen and Sulfur - Environmental Criteria (Second External Review Draft, Aug 2008)
[09/08] EPA is announcing the extension of the deadline for public comment from October 1, 2008, to October 10, 2008, for both of these documents. Comments must be received on or before October 10, 2008.
[08/08]The draft Integrated Science Assessment for Oxides of Nitrogen and Sulfur - Environmental Criteria and the Annexes to this document were announced in a August 12, 2008 Federal Register Notice. Please see Additional Information for steps on providing comments on this report.
Citation:
U.S. EPA. Integrated Science Assessment (ISA) for Oxides of Nitrogen and Sulfur - Environmental Criteria (Second External Review Draft, Aug 2008). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-08/082, 2008.
Impact/Purpose:
The current secondary NAAQS for SOX, set in 1973, is a 3-h average 0.5 ppm of SO2, not to be exceeded more than once per year. The secondary NOX NAAQS is identical to the primary standard set in 1971: 0.053 ppm NO2 as an annual average. These secondary standards are intended to protect against direct damage to vegetation by exposure to gas-phase NOX or SOX. Acute and chronic exposures to SO2 can have phytotoxic effects on vegetation, such as foliar injury, decreased photosynthesis and decreased growth. Similarly, exposure to sufficient concentrations of NO2, NO, PAN, and HNO3 can cause foliar injury, decreased photosynthesis and decreased growth. In addition, these gas-phase NOX may contribute to N saturation in some areas of the U.S. There is little new evidence overall for direct effects of exposure to gas-phase NOX or SOX on vegetation at current concentrations. However, there is some evidence that vegetation in regions with high concentrations of photochemical oxidants may be affected by HNO3 exposure.
Description:
EPA has announced that the Second External Review Draft of the Integrated Science Assessment (ISA) for Oxides of Nitrogen and Sulfur - Environmental Criteria has been made available for independent peer review and public review. This draft ISA document represents a concise synthesis and evaluation of the most policy-relevant science and will ultimately provide the scientific bases for EPA's decision on retaining or revising the current secondary standards for NO2 and SO2.
URLs/Downloads:
Integrated Science Assessment for Oxides of Nitrogen and Sulfur – Environmental Criteria (Second External Review Draft) (PDF, 659 pp, 22838 KB, about PDF)Integrated Science Assessment for Oxides of Nitrogen and Sulfur - Environmental Criteria (Annexes Only) (PDF, 524 pp, 7752 KB, about PDF)
Key findings for the Integrated Science Assessment for Oxides of Nitrogen and Sulfur – Environmental Criteria (PDF, 4 pp, 103 KB, about PDF)
Memo from the NCEA-RTP Director: Ila Cote (PDF, 3 pp, 156 KB, about PDF)
CASAC Project Overview for the Review of the EPA's Integrated Science Assessment for Nitrogen Dioxide and Sulfur Dioxide Secondary (Welfare-based)
CASAC Review of EPA’s Integrated Science Assessment (ISA) for Oxides of Nitrogen and Sulfur – Environmental Criteria (Second External Review Draft) (PDF, 74 pp, 942 KB, about PDF)
FR Notice: Sep 29, 2008
FR Notice: Aug 12, 2008
AGENCY RESPONSE
CHARGE
Peer Review Plan (PDF, NA pp, 35 KB, about PDF)