June 9, 2010Client Alert

EPA Finalizes a More Stringent Sulfur Dioxide Air Quality Standard

Last week, the Environmental Protection Agency (“EPA”) issued a final rule to revise the primary National Ambient Air Quality Standard (“NAAQS”) for sulfur dioxide (“SO2”). The rule revision establishes a 1-hour maximum standard of 75 parts per billion (“ppb”). EPA also revoked the existing 24-hour standard of 140 ppb and an annual standard, citing research that demonstrates short-term SO2 exposures cause the most harm to human health. EPA estimates the revised standard, once fully implemented, will cost industry approximately $1.5 billion to comply, but will create health benefits valued between $13 billion and $33 billion. Coal-fired power plants and other industrial manufacturing facilities will likely be affected most by the more stringent SO2 standard.

The final rule also revises ambient air monitoring requirements for SO2. EPA estimates the revised monitoring requirements will require approximately 41 new monitoring sites to be established nationwide. All new monitoring sites must be operational by January 1, 2013. EPA plans to use monitoring data and air quality modeling to determine compliance with the new SO2 standard.

To implement this final rule, EPA plans to use air dispersion modeling to designate areas as attainment and non-attainment; EPA anticipates finalizing those designations by June 2012. According to EPA, states with designated nonattainment areas will need to submit to EPA revised state implementation plans (“SIPs”) by early 2014, but no later than August 2017. All other states are required to submit updated SIPs to demonstrate how the state will comply with the new standard, account for emission reductions that would result from compliance with the air emission regulations, set enforceable emission limits where necessary and establish timetables and plans to ensure compliance. These SIP updates should be submitted to EPA as soon as possible, but no later than August 2017.

EPA plans to revise the secondary SO2 standards in a separate rulemaking.

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