What is Ozone? What is Ozone?
National Institute of Enviornmental Health Science

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 breaking up pairs of oxygen atoms and reforming them as 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).