US EPA

EPA announced the availability of the first external review draft of the Integrated Science Assessment for Sulfur Oxides– Health Criteria for public comment and independent peer review in a November 24, 2015 Federal Register Notice. This draft document provides EPA’s evaluation and synthesis of the most policy-relevant science related to the health effects of sulfur oxides. When final, it will provide a critical part of the scientific foundation for EPA’s decision regarding the adequacy of the current primary (health-based) National Ambient Air Quality Standard (NAAQS) for sulfur dioxide.

Sulfur oxides are one of six principal (or criteria) pollutants for which EPA has established national ambient air quality standards (NAAQS). For sulfur oxides, the NAAQS are specified in terms of sulfur dioxide (SO2). The Clean Air Act requires EPA to periodically review the scientific basis for these standards by preparing an Integrated Science Assessment. These reviews play a significant role in EPA’s commitment to ensuring a clean and healthy environment for the public.

The draft ISA is part of the Agency’s periodic review of the primary (health-based) NAAQS for SO2. Overall, findings from recent studies strengthen the conclusions from the previous NAAQS review, which was completed in 2010. Results from recent studies strengthen the body of evidence indicating that short-term exposure to SO2 can cause respiratory effects, in particular, effects related to asthma exacerbation. There is more uncertainty regarding the potential for SO2 effects outside the respiratory system.

The Integrated Plan for Review of the Primary NAAQS for SO_x U.S. 2: EPA (2007) identifies key policy-relevant questions that provide a framework for this review of the scientific evidence. These questions frame the entire review of the NAAQS, and thus are informed by both science and policy considerations. The ISA organizes and presents the scientific evidence such that, when considered along with findings from risk analyses and policy considerations, will help the EPA address these questions in completing the NAAQS review.

EPA granted a 30-day extension for the public to provide comments on this draft assessment in a December 24, 2015 Federal Register Notice. In addition EPA announced a public meeting, in a December 21, 2015 Federal Register Notice, to discuss the review of this report. This meeting, hosted by the Clean Air Scientific Advisory Committee (CASAC), was scheduled for January 27-28, 2016. Following the peer review an updated draft will be produced and released for public review and comment. Once finalized, the assessment will be posted on EPA’s website, and will provide a critical part of the scientific foundation for the primary NAAQS for sulfur dioxide.

U.S. EPA. Integrated Science Assessment (ISA) for Sulfur Oxides – Health Criteria (First External Review Draft, Nov 2015). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-15/066, 2015.