EPA Issues New Non-Attainment Areas for Sulfur Dioxide in 16 States

On July 25 the EPA issued non-attainment designations for 29 locations in 16 states that exceeded its sulfur dioxide standard set under the National Air Quality Standard. In its announcement the agency stated the determinations were based on observed data form air emissions stations and weather patterns that contributed to the monitored levels.

According to the EPA, the largest sources of sulfur dioxide (SO2) emissions are from fossil fuel combustion at power plants (73%) and other industrial facilities (20%). Industrial processes like extracting metal from ore, and the burning of high sulfur containing fuels by locomotives, large ships, and non-road equipment also contribute to smaller sources of emissions. SO2 is a criteria pollutant regulated under the Clean Air Act. Under federal law, criteria pollutants like SO2 are required to undergo a review under the National Ambient Air Quality Standards program or NAAQS. This review is required to occur every five years under the Clean Air Act to review of the science upon which the standards are based and the actual standards set for each pollutant. Once a standard is put in place, the EPA Administrator essentially has two options: maintain the existing standard or issue new, more stringent requirements.

States are required by the Clean Air Act to submit State Implementation Plans or SIPs to the EPA to demonstrate how they plan to attain and meet air quality standards laid out in the NAAQS process. If areas or states do not meet EPA's air quality standards they are placed in what is called "non-attainment." Should an area be classified by the EPA under non-attainment, states must impose additional controls on existing sources (ie power plants, factories) to ensure that emissions do not cause “exceedances” of the standards. Significant new construction projects like roads and power plants as well as modified sources must obtain state construction permits in which the applicant must show that emissions will not exceed allowable limits. In non-attainment areas, emissions from new or modified sources must also be offset by reductions in emissions from existing sources. Critics of the NAAQS process, usually business and industry groups, often site designation of non-attainment as a detriment to economic development because of the extra cost associated with projects and permitting requirements involved.

In June 2010, EPA set a one-hour, health-based national air quality standard for sulfur dioxide at 75 parts per billion. According to an EPA fact sheet, “The revised standard will improve public health protection, especially for children, the elderly and people with asthma. These groups are susceptible to health problems, including narrowing of the airways which can cause difficulty breathing and increased asthma symptoms, associated with breathing SO2.” In its initial March 2011 guidance to states for establishing non-attainment boundaries, the determinations for designation would be based on:

  • Air quality data
  • Emissions-related data
  • Meteorology 
  • Geography/topography 
  • Jurisdictional boundaries (e.g., counties, air districts, reservations, metropolitan planning organizations)

The SO2 rule’s non-attainment designation incorporated changes that raised concerns by some environmental groups because it relied more on actual air monitoring data than computer modeling assessments. The so-called “dual pathway” uses both monitoring and modeling, which the groups believe will give less accurate readings. Further, the groups supported the use of computer modeling because it assumed air quality predications in areas without monitoring stations.

For a map of the entire list of non-attainment designations, please click here and for a full list of affected areas/counties please go here. The final rule on the non-attainment goes into effect within 60 days from its publication in the Federal Register. 

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EPA