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About Ozone

Ozone is a pollutant found during the unpleasant and unhealthy air condition called smog. Unlike other air pollutants, ozone is not emitted by pollution sources. Instead, it is formed in the air itself -- high temperatures (over 80°F) and sunlight set off chemical reactions involving so-called ozone precursors, which are hydrocarbons such as gasoline vapors, and nitrogen dioxide from vehicles and smokestacks. The end result is ozone (O3), a highly reactive chemical "cousin" of the oxygen (O2) that we all need to survive.

Ozone Harms Environment and Health

Ozone damages crops and forests, structures, and human health. In the environment, this reactive gas can attack surfaces, fabrics and rubber materials, and is toxic to some crops, vegetation and trees.

When the air is highly polluted with ozone, some people experience smarting eyes and irritated air passages. As ozone levels increase, the severity of the effects increases, and more people become affected. Ozone can cause a variety of respiratory problems, including coughing, shortness of breath, decreased lung function, increased susceptibility to respiratory infection. Asthma and other respiratory ailments may worsen and victims can develop severe respiratory problems.

New York State Warns of High Ozone Levels

Public health officials caution against strenuous outdoor activity when ozone levels are high. To help people decide when to curtail activity, DEC forecasts ozone pollution and, in cooperation with the NYS Department of Health, posts warnings on this website if dangerous conditions are expected to occur. These warnings are also aired through the media, and are available on the toll-free Ozone Hotline at 800-535-1345.

Overall levels of ozone have been systematically declining in New York State and other northeastern states during the past two decades. This decline is the result of motor vehicle exhaust emission controls, lower volatility fuels, stringent control of industrial pollution sources, and other measures that have reduced ozone precursors.

DEC Monitors Ozone Pollution

Unhealthful ozone levels do still occur, however, particularly in New York City and the lower Hudson Valley. DEC's ozone monitoring network provides real-time information on ozone concentrations to the general public, and meets state and federal requirements.

The ozone advisories are developed based on DEC's constant monitoring of ozone levels at 30 sites across the state. Recent results of ozone monitoring can be found in the New York State Ambient Air Quality Report.

Protecting Your Health During a Health Advisory

All people, especially children, those who exercise or work outdoors, and those with respiratory diseases, should limit strenuous outdoor activity during the afternoon and early evening hours, when ozone levels are highest. If you have asthma or other respiratory problems, stay in a cool area and, if possible, where the air is filtered or air-conditioned. Schedule outdoor exercise and children's outdoor activities for the morning hours. Individuals who experience respiratory symptoms may wish to consult their doctors.

Reducing Ozone Pollution

Reducing ozone in the air requires action on multiple fronts.

  • DEC controls pollution from smokestacks through a statewide permitting program.
  • State and federal controls on vehicle exhausts, along with programs requiring inspection and maintenance of vehicle emission control devices, reduce emission of nitrogen oxides.
  • Use of low volatility fuels during the warm months reduces hydrocarbon vapors in the air.
  • Drivers can prefer low-emission vehicles, limit their driving, and refuel with care to avoid spillage.
  • Homeowners can use water-based paints, store and handle gasoline and other solvents carefully.

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