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Ground-level ozone levels appear to be stable in Ann Arbor, but we remain "out of attainment" above the Federal 8-hour standard. Recent changes to the 1-hour ozone standard (from 0.08 to 0.075ppm) mean that Washtenaw County will remain out of attainment for this standard also. Ground level ozone results in poorer air quality on many hot summer days and causes our area to be declared "out of attainment" for ground-level ozone standards. Since 1994, southeast Michigan has reached unhealthy levels of ozone on 122 days, also called "Action Days. " The average number of Action Days per year was 12, though 25 Action alerts were issued in 1999 but only 5 or less in the last five years. The recent decrease in ozone action days may be due to fewer hot weather events.
Source: U.S. Environmental Protection Agency
Last updated: June 2009 |
What is ozone?
In the Earth's lower atmosphere, near ground level, ozone is formed when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources react chemically in the presence of sunlight. Ozone at ground level is a harmful air pollutant. Ozone is not emitted directly into the air but formed by the reaction of volatile organic compounds, nitrogen oxides and other chemicals in the presence of heat and sunlight, particularly in hot summer weather. Ground level ozone is one of the primary indicators used to measure air quality.
Ozone also naturally occurs in the the upper atmosphere (6-30 miles above the surface). Here it creates a protective layer that shields us from harmful ultraviolet rays from the sun. Manmade chemicals are destroying this upper ozone layer, allowing more ultraviolet rays to reach Earth's surface. Areas near the North and South poles are especially depleted.
Source: AIRNow, U.S. Government Collaborative Site
How does ozone affect the environment?
Ozone, the main ingredient of smog, presents a serious air quality problem in many parts of the United States. Even at low levels, ozone can cause a number of respiratory effects. Active adults who spend lots of time outside, and at- risk populations, such as those with lung and heart conditions, children, and the elderly, are particularly vulnerable to the health affects of ozone.
What can we expect as a result of being "Out of Attainment?"
Motorists would have seen some significant changes due to the County’s original designation as "moderate" non-attainment including emissions testing of all automobiles in the Ann Arbor. Some areas in the country that have failed to meet attainment standards have lost federal transportation funds. However, Washtenaw County has been redesignated as “marginal” attainment and this redesignation will require fewer actions in the county. For more information read the SEMCOG Ozone Attainment Strategy for Southeast Michigan (PDF). One step undertaken to reduce ozone levels is that the MDEQ has adopted a new regulation for consumer products containing Volatile Organic Compounds or VOCs. MDEQ Rule 660 adopts the OTC published rule “Model Rule for Consumer Products” that contains the following provisions:
- The rule limits VOCs in the contents of consumer products including personal care products, household products, automotive aftermarket products, adhesives and sealants, insecticides, coatings and related products (except architectural and maintenance coatings), and other miscellaneous products. The rule stipulates that no person shall sell, supply, offer for sale, or manufacture for sale, in the state of Michigan all of the affected consumer products (mostly aerosols and sprays) unless the VOC content limits in the rule’s Table of Standards are adhered to in the formulation of those consumer products.
- The rule further prohibits sale or manufacture of antiperspirants and deodorants that contain certain toxic air contaminants as defined in the referenced and adopted OTC’s Model Rule.
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