EPA Releases New Ozone Standard

Today the Department of Natural Resources (DNR) Air Quality Bureau received notification of the U.S. Environmental Protection Agency’s (EPA) new National Ambient Air Quality Standards (NAAQS) for Ozone: an 8-hour average of 75 parts per billion (ppb) for both primary and secondary NAAQS. Previously the 8-hour average ozone standard was 80 ppb.

Stephan L. Johnson, Administrator of the EPA, stated that the reason for the more stringent primary standard is to provide an adequate margin of public safety to protect human health that recent scientific evidence has revealed is necessary. The secondary standard is for protection of the public welfare, which includes protection of vegetation and the ecosystem.

Monitored areas will not be determined to be out of attainment with the 75 ppb ozone standard until 2010, said Johnson. At that time areas will have as many as 20 years to comply with the new standard.

Iowa has been in attainment for the 80 ppb ozone standard since its inception in 1997 and continues to be in attainment for the new 75 ppb standard. However, ozone averages for the three year period through 2007 are close to the 75 ppb threshold in some areas of the state. The Iowa Ozone Design Values for 2005 through 2007 and previous three-year periods, are posted at:

www.iowacleanair.com/prof/monitor/monitor.html.

Ozone (O3) is a secondary pollutant that forms as a component of photochemical smog. Pollution forms when nitrogen oxides and volatile organic compounds (VOCs) react in the presence of heat and sunlight. Nitrogen oxides are formed by fossil fuel combustion, and VOCs are composed primarily of carbon and hydrogen that evaporate into the air. Ninety percent of VOCs are created by vehicles and industrial activities. Ozone levels are affected by climate, sunlight, geographic features, and atmospheric conditions and weather.

The 8-hour standard is actually an 8-hour average based on the 3-year average of the fourth highest daily maximum 8-hour average. Because of the “rounding” procedure that was in effect, the 3-year average could be as great as 84 ppb and still be in attainment as 80 ppb. The new standard will use a more restrictive rounding procedure: a design value over 75 ppb will be considered out of attainment.

Ozone exposure correlates to increased respiratory disease and higher mortality rates. Ozone can inflame and damage the lining of the lungs. Within a few days, the damaged cells are shed and replaced, much like the skin peels after sunburn. Over a long time period, lung tissue may become permanently scarred, resulting in permanent loss of lung function and a lower quality of life. When ozone levels are high, more people with asthma have attacks that require a doctor’s attention or use of medication. Ozone also makes people more sensitive to allergens such as pets, pollen and dust mites which trigger asthma attacks.

High levels of ozone also damage plants and reduce agricultural yields by destroying chlorophyll.

Questions should be directed to Jim McGraw, at (515) 242-5167, or Sean Fitzsimmons, at (515) 281-8923.