History of Ozone in West Michigan
The United States Environmental Protection Agency (EPA) and the State of Michigan together share responsibility for implementing federal Clean Air Act requirements. In this capacity, the Michigan Department of Environmental Quality (MDEQ) monitors air pollution levels and works with local community government and planning agencies to develop attainment plans that bring areas in violation of air quality standards into compliance.
The West Michigan Clean Air Coalition, in cooperation with its members and partners as well as the MDEQ, works to promote measures that improve air quality throughout the region. Below is a brief history of ozone air quality compliance in West Michigan and our historic progress improving air quality for this area.
Ozone Standards
The 1-Hour Standard
The old ozone standard was an exceedance-based calculation where a violation occurred if a monitor recorded more than three days where the 1-hour ozone values were greater than 124 parts per billion in a three year period. From 1978 through 1994, Kent, Ottawa, Muskegon, and Allegan Counties were designated as nonattainment areas, because ozone levels exceeded the standard.
Over 20 years of emission control efforts resulted in the West Michigan counties meeting the 1-hour ozone standard. The improvement in air quality qualified these areas to be redesignated as “attainment areas.” The Kent and Ottawa County area was redesignated as attainment in 1996. Muskegon was redesignated as attainment in 2000, and Allegan County became attainment in 2001. As of June 15, 2005, all areas in Michigan are no longer subject to the 1-hour ozone standard.
The 8-Hour Standard
In 1997, the EPA adopted a new more stringent 8-hour ozone standard. This standard is based on concentration levels averaged over an 8-hour period instead of the number of exceedances. The 8-hour standard was considered more protective of public health for population groups especially sensitive to air pollution…children who are active outdoors, adults engaged in moderate to strenuous outdoor activities, and individuals with respiratory disease, such as asthma.
Designations for the 8-hour ozone standard were made by the EPA on June 15, 2004. In West Michigan Kent, Ottawa, Muskegon, and Allegan were all designated as nonattainment. The Muskegon nonattainment area was also classified as marginal based on the severity of the ozone pollution measured there. Overall air quality has since improved in West Michigan, and in response to requests by the Michigan Department of Environmental Quality (DEQ), EPA has redesignated Kent, Ottawa, and Muskegon Counties as attainment for the 1997 8-hour ozone standard. The air quality data for Allegan County is still showing a violation of the 1997 standard at that monitor. Click here to see a current ozone attainment map.
2008 National Ambient Air Quality Standards (NAAQS)
On March 12, 2008, the EPA significantly strenghtened the National Ambient Qair Quality Standards (NAAQS) for ground-lvel ozone. These revisions reflect new sicentific evidence from the Clean Air Scientific Advisory Committee about ozone and its effects on the public health and environment. The EPA's 1997 ozone standard was set at 0.08 ppm (parts-per-million) which was effectivly 0.084 ppm due to rounding over an 8-hour period. The new strenghtened NAAQS Standard for ground-level ozone has been set at 0.075 ppm for an 8-hour period. The EPA also specified the level of the standard to the nearest thousandth of a ppm (aka the "third decimal place"), which eliminates the need for rounding under the new standard.
A network of air quality monitors are located in the West Michigan counties. Ozone monitors operate from April through September because ozone formation is associated with hot summer weather conditions. The DEQ also operates monitors to measure fine particle levels, and other pollutants all year round.
The Air Quality Index (AQI) and Ozone Action
The AQI is a color-coded daily air health indicator that provides a snapshot of current air quality to the public. Both fine particle and ground-level ozone levels are reported through the AQI which was also revised as of March 12, 2008 to reflect the new NAAQS standard for ground-level ozone. The AQI ozone breakpoint of 75 parts-per-billion (or 0.075 parts-per-million) is the “unhealthy for sensitive groups” (orange) category which represents the population at greatest risk. When ozone levels are expected to approach or exceed that level, Ozone Action Days are declared and individuals and businesses are asked to make no cost / low cost choices to reduce pollution. The number of high ozone days fluctuates each summer according to the weather conditions. An average summer in West Michigan in past years had 15 Ozone Action Days. In more recent years, fewer Ozone Action Days have been announced, however, under the new strenghtened ground-level ozone standard, Michigan Department of Environmental Quality Meteorologists anticipate significantly more days forecast as Ozone Action Days in the coming years.
Daily AQI values should not be confused with the 8-hour ozone standard or the fine particle average-based standards. The AQI and the air quality standards are not interchangeable.
The West Michigan Clean Air Coalition is a partnership of businesses, academic institutions, government agencies, industry, and non-profit organizations in Kent, Ottawa, Muskegon, and Kalamazoo counties working together to achieve cleaner air in the region through the education and promotion of voluntary emission reduction activities.