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Ozone is a special form of oxygen. Like ordinary oxygen, ozone is one of the many gases in the air we breathe. Like oxygen, ozone is made up of oxygen molecules. But, while the molecules of ordinary oxygen are made up of two chemically linked oxygen atoms, the molecules of ozone are made of three such atoms. With its third atom of oxygen, ozone is not very stable—that is, it ordinarily doesn’t last very long.

A little ozone occurs naturally. An energy source such as lightning can produce it—temporarily braking up pairs of oxygen atoms and reforming them chemically linked clusters of three oxygen atoms: ozone.

People, other animals and plants tolerate such naturally occurring, short-lived ozone pretty well. But when ozone builds up—generally as a result of our use of fossil fuels—it reacts very strongly with animal and plant tissues, and even damages tough materials such as rubber, plastics and outdoor paints.

You’ve probably seen hydrogen peroxide fizz—and perhaps felt it burn your gums or skin tissues, or “smart.” Like ozone, hydrogen peroxide is closely related to a very stable molecule: water, or H2O. With an added oxygen atom, it changes to H2O2, becoming very reactive.

The fizz and burn of hydrogen peroxide on a scratch or wound illustrate how, at high concentrations, ozone’s own strong reactivity can irritate and damage the sensitive tissues of your eyes, lungs, nose, sinuses and throat, causing burning eyes, shortness of breath, chest tightness, wheezing, coughing and nausea.


The sustained, higher levels of ozone that cause these effects usually begin with human activity.

That is, when we use electricity for our lights, computer and TV, when we heat our houses and run our cars and SUVs, or even when we roast chestnuts on an open fire or charcoal a steak, these activities often require the burning of fossil fuels—hydrocarbons such as gasoline, heating oil, firewood, charcoal and the coal for power plants. This combustion releases oxides of nitrogen, which are gaseous combinations of oxygen and nitrogen, nitrogen being another common gas in our atmosphere. One of these combinations is nitrogen dioxide (NO2). When NO2 absorbs energy from sunlight, it breaks down to nitric oxide (NO) and a free oxygen atom.

The free oxygen atom then barges into the oxygen pair to form the linked triplet of ozone (O3).

When OZONE accumulates it hurts our crops, pets and people

Normally, ozone converts back to oxygen. However, airborne hydrocarbons (from motor vehicles, industrial emissions and other kinds of incomplete combustion and solvent use) can disrupt this conversion, allowing the ozone to accumulate. Because sunlight and heat play roles in the smog process, ozone concentrations most often rise in the warmer months of the year and peak in the warmer hours of of the day.

While winds might dissipate the ozone, temperature inversions frequently occurring during warm weather over many cities can hold down and stagnate the lower atmosphere, allowing ozone to build up. And there you have it: grey, thick, photochemical smog—urban smog.

Thus, the centers of ozone pollution are the great centers and suburbs of humankind’s activity: Los Angeles, Houston, Atlanta, New York, Boston and other large metropolitan areas. (That’s why in some cities in developing countries, people are somewhat proud of smog—as a sign of industrialization’s progress.) In rural areas, less ozone is likely to accumulate. There are fewer gasoline automobiles, homes and factories. In addition, moisture in rural soil and trees absorbs some of the radiant energy from the sun, keeping these areas cooler than nearby cities. But rural areas do not escape the effects of ozone entirely. Trees themselves generate some hydrocarbons and add to ozone levels.

Many power plants that burn fossil fuels are in rural areas, increasing the concentrations of oxides of nitrogen in rural air. According to “the weatherman,” the National Oceanic and Atmospheric Administration, rural sections of the East and South have among the highest summer ozone readings in North America partly as a result of spillover from cities and suburbs.

Crops suffer as well, with up to $3 billion in agricultural losses a year in the United States. The forests that we harvest for paper and building materials are also susceptible to ozone-induced damage. In China, heavy regional haze may cut food production 10-30 percent, according to one estimate, contributing to food scarcities and hunger.

How OZONE disturbs your body

Inhaled ozone travels down the windpipe and enters the lungs through the large bronchial tubes, which branch into smaller airways, or bronchioles. At the end of the bronchioles are tiny air sacs called alveoli, which fill up and expand like little balloons to put oxygen into the bloodstream. Ozone primarily injures these key oxygen exchangers, the alveoli, along with the bronchioles.

Animals also suffer from ozone. Studies demonstrate how ozone exposure injures their lung cells and causes unusual changes in lung tissue. Other studies have shown that ozone can make people more susceptible to bacterial pneumonia, a potential killer.

People with existing lung diseases—asthma, bronchitis, or emphysema—are particularly vulnerable to the respiratory effects of ozone.

There are also particularly sensitive individuals.

What can I do?

In terms of ozone concentrations in the lower atmosphere, you can:

  • Run early or late: protect yourself in warm weather, when ozone concentrates, by exercising in non-congested areas, in the mornings, before ozone levels rise with daily temperatures, or in the evenings, after they’ve declined.
  • Keep Car Tuned, Tires Inflated: Protect your environment by keeping your car in tune and your tires inflated to the recommended pressure, and by using your car sparingly, finding alternatives.
  • Cap chemicals: Keep household cleaners, solvents and other home and garden chemicals tightly sealed, to reduce the evaporation of volatile organic compounds which contribute to the hydrocarbon content of the atmosphere.
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  • Limit burning: Whether your locality permits it or not, avoid burning trash and building inefficient fires, such as smoky grills and fireplaces—especially if your area is experiencing alerts.
  • Conserve power: Join in your electric utility’s conservation programs, such as periodic air conditioning cut-backs that also reduce your bills. Support local ordinances and regulations related to conservation and to burning and smoke restrictions, so that you and your neighbors can breathe easier.

In terms of the stratosphere, you can:

  • Repair Leaky AC: Make sure that old-style refrigerants used in your auto are not released into the atmosphere but are recovered in a government-approved program, as required by law. Repair leaky units before refilling them.
  • Dispose of Fridge or AC Carefully: Check with your local authorities about the proper disposal of old refrigerators and air conditioners.
  • Protect Skin: Prevent sunburn and reduce your risk of skin cancer, malignant melanomas and cataracts by protecting yourself with a wide-brim hat, tight-weave clothing, sunglasses and a sunscreen of SPF 15 to 30.

Source: The National Institute of Environmental Health Sciences


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