In a final rule (January 9, 2018, FR), the EPA issued the third of four expected area designations under the 2010 National Ambient Air Quality Standards (NAAQS) for sulfur dioxide (SO2).
In this round, the Agency has designated 6 areas as nonattainment; 23 areas as unclassifiable; and the rest of the areas covered by this round in all states, territories, and tribal lands as attainment/unclassifiable. In a future fourth round, the EPA expects to designate all remaining undesignated areas (approximately 50 areas) where states have installed and begun timely operation of a new SO2 monitoring network.
SIPs Due in 18 Months
For areas designated as nonattainment, the Clean Air Act (CAA) directs states to develop and submit to the EPA state implementation plans (SIPs) within 18 months of the effective date (April 9, 2018) of the final designation rule. SIPs must describe air pollution control measures that are being or will be implemented to enable nonattainment areas to achieve attainment with the NAAQS no later than 5 years from the rule’s effective date. Six months after the 5-year deadline, the EPA must determine whether the area has attained the standard. If the Agency determines that an area has failed to meet the standard, the state has 12 months to submit a SIP revision that demonstrates that the area will attain the standard within 5 years of EPA’s determination.
Combustion of coal and oil accounts for about 85 percent of all SO2 air pollution in the United States. Once designated as nonattainment, areas are subject to nonattainment New Source Review (NSR), a permitting program for industrial facilities intended to ensure that new and modified sources of pollution do not impede progress toward cleaner air.
In July 2013, the EPA completed an initial round of designations under the 2010 SO2 NAAQS for certain areas of the country. Following the initial designations, three lawsuits were filed against the EPA in different U.S. district courts, alleging that the Agency had failed to perform its nondiscretionary duty under the CAA by not designating all portions of the country by the June 2, 2013, deadline. In one of those cases, on March 2, 2015, the U.S. District Court for the Northern District of California entered an enforceable order for the EPA to complete the area designations by the following three deadlines:
Round 2, July 12, 2016. In July and December 2016, the EPA designated 65 additional areas in 24 states—7 nonattainment areas, 41 unclassifiable/attainment areas, and 17 unclassifiable areas.
Round 3, covering the current action, had a deadline of December 3, 2017.
Round 4, December 31, 2020. The Agency must complete SO2 designations for all remaining areas of the country.
According to the EPA, the current designations are based on the Agency’s nationwide analytical approach and technical assessment of and conclusions regarding the weight of evidence for each area. For example, with respect to air quality monitoring data, the EPA considered available data from at least the most recent 3 calendar years, 2014–2016. In the modeling runs conducted by states or third parties, the impacts of the actual emissions for recent 3-year periods (e.g., 2012–2014, 2013–2015, 2014–2016) were considered. In some cases, the modeling evaluated current allowable emissions limits in lieu of or as a supplement to modeling of actual emissions. The Agency says it may consider early certified 2015–2017 monitoring data or other documentation that demonstrates attainment. This information would need to be submitted to the EPA by February 28, 2018.