The United States Environmental Protection Agency (EPA) has proposed sweeping new National Ambient Air Quality Standards (NAAQS) for ozone and particulate matter (PM) which will require many new or modified sources of air emissions to meet stricter emission limits. Under the federal Clean Air Act, each state is required to adopt statutes, regulations or other air pollution control measures to ensure that it complies with the NAAQS. Generally, more stringent air emission requirements are applied in those areas of a state that do not comply with the NAAQS.
Ground-level ozone levels are generally controlled by restricting emissions of volatile organic compounds (VOCs) and oxides of nitrogen (NOx). EPA proposes to reduce the ozone NAAQS from .12 parts per million (ppm) measured over a one-hour period to .08 ppm measured over an eight-hour period. Currently an area that exceeds the NAAQS more than once per year over a three-year period is deemed not to have attained compliance with the NAAQS, which is termed nonattainment area, must implement ozone-reducing measures, such as stringent controls of VOC and/or NOx emissions from existing emission sources and testing of automobile emissions. EPA proposes that any area where the third highest daily maximum eight-hour concentration in each year, averaged over three years, exceeds the limit, be deemed a nonattainment area. EPA also seeks comment on a .07 or .09 ppm limit. Several areas in Michigan that have recently been designated as attainment for current ozone NAAQS could become nonattainment areas again if the proposed ozone NAAQS is adopted, as could areas of Michigan that have never been nonattainment for ozone before.
EPA also proposes to adopt a new annual PM-2.5 standard limiting ambient concentrations of particles measuring 2.5 microns or less to average concentrations of 15 micrograms per cubic meter (5g/m3) annually. In addition, EPA proposes a 24-hour PM-2.5 limit of 50 5g/m3. The agency also seeks comment on two other PM-2.5 limit options: (1) an annual average of up to 20 5g/m3 and a 24-hour limit of 65 5g/m3; and (2) an annual average of approximately 12 5g/m3 and a 24-hour limit in a range of 20-50 5g/m3.
EPA proposes to retain its current PM-10 standard limiting ambient concentrations of particles measuring 10 microns or smaller to average concentrations of 50 5g/m3, with a 24-hour limit of 150 5g/m3. The agency is also seeking comment on revoking the 24-hour PM-10 limit.
If adopted, the regulations will be required to impose stricter emission limits on new and modified sources. Michigan may be required to impose additional restrictions on existing sources in order to demonstrate that all areas of Michigan will be able to achieve the new NAAQS. Michigan Department of Environmental Quality Director Russell Harding issued a statement on the proposal questioning whether the benefits of the proposed rules would outweigh the costs to industry and consumers. Harding said that Governor Engler has asked the Michigan Environmental Science Board "to thoroughly evaluate the air quality and human health assumptions on which EPA's proposals are based."
This article was written by S. Lee Johnson, an associate in our Environmental Department. and appeared in the December, 1996 issue of our newsletter, Michigan Environmental Compliance Update, published by M. Lee Smith Publishers.