What is Ozone?
Ozone is a gas that occurs both in the Earth's upper atmosphere and at ground level. Ozone can be "good" or "bad" for people's health and for the environment, depending on its location in the atmosphere. The stratospheric or "good" ozone protects life on Earth from the sun's harmful ultraviolet (UV) rays. Ozone at ground level is a harmful pollutant and is designated as a “criteria” air pollutant by the EPA.
Ground level ozone is formed when intense sunlight interacts with oxides of nitrogen (NOx) and volatile organic compounds (VOCs). Ozone forming NOx and VOCs come from many sources including vehicle and power plant emissions, lawn mowers and other fuel burning equipment, and vapors from gasoline, paints, and industrial processes.
Ozone pollution is a concern during the summer months because strong sunlight and hot weather result in harmful ozone concentrations in the air we breathe. Many urban and suburban areas throughout the United States have high levels of ground level ozone. But many rural areas of the country are also subject to high ozone levels as winds carry emissions hundreds of miles away from their original sources.
Breathing ozone, a primary component of urban smog, can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. Ground-level ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may permanently scar lung tissue. Children and those with pre-existing lung problems (such as asthma) are sensitive to the health effects of ozone. Even healthy adults involved in moderate or strenuous outdoor activities can experience the unhealthy effects of ozone.
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What is the current National Ambient Air Quality Standard for Ozone?
The primary (public health based) ozone standard has been revised several times, from a one hour standard of .12 parts per million established in 1991, to an 8 hour standard of .84 ppm in 1997, to the current 8 hour standard of .75 ppm. In each revision, the standard has been lowered, and has become more protective of public health. EPA currently is reviewing the 2008 8 hour standard, and plans to lower it further, based on the recommendations of its scientific advisory board, the Clean Air Scientific Advisory Committee (CASAC). The primary standard will be lowered from .75 ppm to between .60-.70 ppm. EPA plans to announce the new ozone standard by August 2010.
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What Can You Do to Reduce Ozone Pollution?
To reduce ozone pollution and improve regional air quality
- Carpool, telecommute, or take mass transit to get to work
- Limit driving and combine errands
- Limit engine idling
- Use environmentally safe paints and cleaning products whenever possible
- Conserve energy at home, at work, and everywhere to reduce power demand.
Improve your home's energy efficiency. Power plants are one of the main sources of NOx, oxides of nitrogen, an ozone forming (precursor) pollutant. Reducing energy demand in your home will result in fewer ozone forming emissions from power plants.
On Air Quality Action Days, when ozone levels are forecast to be unhealthy, you should also
- Refuel vehicles after dark, when emissions are less likely to produce ozone
- Delay using gasoline-powered lawn and garden equipment, including mowers
- Wait for a cooler day to use oil-based paints or switch to non-solvent or low VOC-based paints
- Delay using household, workshop, and garden chemicals
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Further Information
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