One-hour NAAQS for Sulfur Dioxide (SO2)
Author: Jeffrey Barwick | Category: Civil Environmental Engineer, Environmental ConsultingOn June 22, 2010, the EPA revised the Code of Federal Regulations pertaining to the National Ambient Air Quality Standards (NAAQS) for Sulfur Dioxide (SO2) emissions. The changes significantly strengthened EPA’s regulation of SO2 emissions from industry. Some changes of particular importance include the following.
- EPA has removed the former NAAQS for SO2, which were based on 24-hour and one-year averaging techniques; however, this removal is not indicative a “loosening” of environmental regulation.
- In place of the former NAAQS for SO2, EPA has promulgated a 1-hour standard of 75-parts per billion.
- EPA, in a fact sheet on the change, stated the new 1-hour standard would continue to prevent SO2 concentrations from exceeding the (now) former 24-hour and annual health-based standards.
- The revisions described above are termed “primary” standards by EPA
- There will be further rules, under development now, which will be termed “secondary” standards. Secondary standards will impose further regulation on SO2 emissions.
Facilities that use air dispersion modeling to demonstrate compliance will most likely face significant difficulties meeting the 1-hour concentration of 75-ppb. At this time, there are still several unknown factors related to the implementation of the primary standards rule, including upgrades to the United States’ air quality monitoring infrastructure that may be required, and the designation of many more “non-attainment areas” for SO2 as a result of the new standards.
However, the more stringent standards will doubtless present compliance challenges to industries that emit SOx as part of their process(es). If you have any questions about what you need to do to comply with the SO2 NAAQS, please feel free to contact me at (803) 376-6034 ext. 6105.
