Primary National Ambient Air Quality Standard (NAAQS) for Sulfur Dioxide
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February 25, 2019, based on a review of the full body of currently available scientific evidence and exposure/risk information, the EPA issued a decision to retain the existing primary National Ambient Air Quality Standard (NAAQS) for sulfur dioxide (SO2). EPA’s decision is based on its judgment that the current NAAQS protects the public health, with an adequate margin of safety, including the health of at-risk populations with asthma.
The existing standard, established in 2010, is 75 parts per billion based on the 3-year average of the 99th percentile of the yearly distribution of 1-hour daily maximum concentrations.
01/26/2011 – Denial of Petitions to Reconsider