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First Iowa Exceedance of New Ozone Standard

  • 6/14/2016 12:06:00 PM
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WINDSOR HEIGHTS - An ozone monitoring site in Scott County Park north of Davenport recorded an eight-hour average ozone level of 71 parts per billion yesterday, June 13. The U.S. Environmental Protection Agency’s eight-hour average health threshold is 70 parts per billion.

Clouds and possible thunderstorms are expected to keep ozone levels below the health threshold today.

Iowans with respiratory or heart disease, the elderly, and children are the most susceptible to ozone above the level of the health standard and should consider limiting prolonged outdoor exertion when levels are high.

EPA strengthened the federal eight-hour ozone standard on Dec. 28, 2015, from 75 to 70 parts per billion. The Scott County Park exceedance is the first recorded exceedance since the new standard took effect.

Light winds, clear skies and high temperatures favor the formation of photochemical smog. In these conditions, volatile organic compounds react with nitrogen oxide resulting in an increase in ozone. Volatile organic compounds are emitted from the evaporation of consumer and industrial solvents, such as the evaporation from gas tanks in vehicles or mowers. Nitrogen oxides are created by combustion, and are contained in the exhaust from vehicles and coal-fired boilers.

EPA’s national air quality map is available online at