History of Air Quality 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 1-Hour 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 in 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
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 (MDEQ), EPA has redesignated Kent, Ottawa, Muskegon, and Allegan Counties as attainment for the 1997 8-hour ozone standard. For more information on county attainment statuses in Michigan, please click here.
Particulate Matter Standards
National Ambient Air Quality Standards (NAAQS) for particulate matter
were first set in 1971. Total suspended particulate (TSP) was the first
indicator used to represent suspended particles in the ambient air. There
were secondary standards, which were welfare standards, and primary standards,
which were public health standards. An area in Kent County was designated
nonattainment of the secondary TSP standard in 1978. An area in Muskegon
County was also designated as exceeding the secondary standard in 1978,
with a correction in 1981.
In 1997, the EPA established an annual standard and a 24-hour standard for PM2.5, or particulate matter with an aerodynamic diameter less than 2.5 microns. The PM10 standard remained in place. The first nonattainment designations for the 1997 standard were made in 2005. No areas in West Michigan were in nonattainment.
In 2006, the EPA revised the 24-hour PM2.5 standard and retained the existing annual PM2.5 standard. Particulate matter levels in West Michigan were exceptionally high in 2005, and therefore, the design value for Kent County for 2004-2006 was 37 ug/m3 and for 2005-2007 was 36 ug/m3. The 24-hour NAAQS is set at 35 ug/m3.
The EPA sent Governor Granholm a letter, dated August 18, 2008, indicating
that Kent and Ottawa Counties should be designated as nonattainment for
the 2006 24-hour PM2.5 standard based on monitored data from 2005-2007.
Recent Revisions of the National Ambient Air Quality Standards (NAAQS)
On October 1, 2015, EPA strengthened the National Ambient Air Quality Standards (NAAQS) for ground-level ozone to 70 parts per billion (ppb), based on extensive scientific evidence about ozone’s effects on public health and welfare. The updated standards will improve public health protection, particularly for at-risk groups including children, older adults, people of all ages who have lung diseases such as asthma, and people who are active outdoors, especially outdoor workers. They also will improve the health of trees, plants and ecosystems. To read more about the new ozone standard, please click here.
The National Ambient Air Quality Standards for ozone were last revised in March of 2008. The EPA's 1997 ozone standard was set at 0.08 ppm (parts-per-million) which was effectively 0.084 ppm due to rounding over an 8-hour period. The 2008 NAAQS standard for ground-level ozone was 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. The current NAAQS 24-hour standard for fine particulate matter was established by the EPA in 2006 and is 35 µg/m³. The previous 24-hour standard of 65 µg/m³ was established in July of 1997 . The annual standard for particulate matter of 15 µg/m³ was established in 1997 and remains in effect today.
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 particulate matter levels and other pollutants year-round.
The Air Quality Index (AQI) and Clean Air Action
The AQI is a color-coded daily air health indicator that provides a snapshot of current air quality to the public. Both fine particulate matter 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 76 parts-per-billion (or 0.076 parts-per-million) and the AQI particulate matter breakpoint of 35.5 µg/m³ are the “unhealthy for sensitive groups” (orange) category which represents the population at greatest risk. When ozone or particulate matter levels are expected to approach or exceed that level, Clean Air Action Days are declared and individuals and businesses are asked to make no cost / low cost choices to reduce pollution. The number of high pollution days fluctuates each year according to the weather conditions.
Daily AQI values should not be confused with the 8-hour ozone standard or the fine particulate matter 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.
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