What are Ozone Action Days?

Citizens can help reduce ozone levels by adopting simple steps on Ozone Action Days and every day.

Summer weather is sunshine and warm temperatures, but when these combine with air pollution, it also can mean an increase in ozone formation.

Ozone (O3), the primary ingredient in smog, is a gas that is formed through the chemical reaction between oxides of Nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. Emissions from motor vehicles, gas vapors, chemical solvents, industrial facilities and electric utilities are the main sources of NOx and VOCs.

Ozone is either good or bad depending on its location. Good ozone, found in the stratosphere, protects the Earth from the sun’s harmful ultraviolet radiation. Bad ozone is at ground level and impacts health and causes depletion of the good ozone layer. See the Michigan State University Extension article, The good, the bad and the ugly about ozone, for a detailed discussion on ozone.

A number of communities in Southwest and Southeast Michigan have just experienced the first “Ozone Action Days” of the year. However, these days were below the yearly average and occurred later in the season than over the past decade. The average number of Ozone Action Days from 2004 through 2103 was 5.5 in Detroit and 7.1 in Grand Rapids with the earliest “Action Day” announced on May 24, 2012.

What is an Ozone Action Day? The Department of Environmental Quality monitors daily conditions and if conditions indicate that the temperature and pollution are high enough, it will create elevated amount of ground-level ozone. For people who work or exercise strenuously outdoors or have respiratory conditions, ozone can be a threat to their health as well as an environmental concern.

On Ozone Action Days, citizens are asked to take steps to reduce the creation of ozone to protect human health and the environment and meet new stricter national air quality standards for ozone. For example, on July 22, 2014, an Ozone Action Day, there was a one-hour ozone reading of 85 (EPA standard is 75 maximum) while on July 24, the one-hour reading was 40.

While we cannot do anything about changing the weather, citizens can have a positive impact in reducing ozone through their daily actions.

What can be done to reduce the bad ozone and protect the good ozone?

  • Be aware of Ozone Actions Days. These are days when high temperatures and air pollution combine to form high levels of ground level ozone.
  • Limit outdoor activities on Ozone Action Days.
  • Conserve energy. This reduces emissions from electric facilities.
  • Limit motor vehicle travel by putting trips off or combining several trips and planning the most efficient route. Use the newest vehicle with the best emission controls to reduce pollution.
  • Avoid filling up motor vehicles. If you must get gas, do it in early morning or evening when temperatures are lower.
  • Avoid vehicle idling. Idling for more than ten seconds wastes gas and adds harmful emissions to the air.
  • Avoid using drive-thru restaurants, banks and stores. Park and go inside to save gas and reduce emissions.
  • Put off mowing grass or using other gas powered lawn equipment to reduce emissions.
  • Use household and garden chemicals sparingly.
  • Use low VOC paints and solvents.

Ground-level ozone lasts for many years. It rises through the atmosphere and will deplete the protective ozone layer causing increased health issues. Taking steps to reduce harmful emissions will have a lasting positive impact on health and the environment.

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