The term “ozone” has appeared in numerous magazine and newspaper articles and has been a subject of discussion on both radio and television. Despite all the publicity surrounding this term, however, many people are still confused by it. The confusion arises from the fact that ozone is both beneficial and harmful. We know that the ozone layer in the upper atmosphere acts as a filter for the sun's ultraviolet rays, reducing the amount of radiation that reaches the earth's surface. At ground level, though, high concentrations of ozone can be harmful.

The Ozone Layer
Ozone gas forms a layer all around the earth high in the stratosphere. It serves as a vital and effective protective barrier from the sun's ultraviolet rays. In recent years, scientists have sounded alarms internationally about the depletion of the ozone layer, citing chemical pollution as the major cause.

A specific class of chemical compounds called chlorofluorocarbons (CFCs) are most often identified as ozone destroyers. CFCs were once widely used in everything from air conditioner coolants to the propellant in aerosol cans but have now been banned in most developed nations, including the U.S.

Many scientists believe much more needs to be done to protect the ozone layer, and international efforts are ongoing.

Ozone Pollution
Ozone pollution is really an increase in the concentration of ozone in the air at ground level. Because sunlight has a critical role in its formation, ozone pollution is principally a daytime problem in the summer months. Ground-level ozone is produced when sunlight combines with hydrocarbons and nitrogen oxide, two compounds produced by cars, trucks, factories, and power-generating plants, and found wherever gasoline, diesel fuel, kerosene, oil, or natural gas are combusted. Urban areas with heavy traffic, and large industrialized communities, are the primary areas with ozone problems.

When temperatures are high and there is little wind, ground-level ozone can reach levels that are dangerous to the health. Weathermen can predict when an area will be subject to high ozone levels and issue alerts according to the Environmental Protection Agency's Air Quality Index (AQI). When the AQI is in the moderate, or yellow, category, for ozone, people who are unusually sensitive may experience problems. A higher level of alert (orange, red, purple, or maroon) carries added risk.

Who Is At Risk?
Some people are at especially high risk for health problems associated with ozone. These include children, who normally spend a lot of time outdoors in the summer months when ozone is highest; active adults who exercise or work vigorously outdoors; people with asthma or other respiratory problems; and people who, for reasons as yet unknown to medical science, are simply more susceptible to ozone's effects. Ozone can effect the health by:

Irritating the respiratory system, causing coughing, throat irritation, and/or an uncomfortable sensation in the chest.

• Reducing lung function, making it more difficult to breath as deeply or vigorously as normal.
• Aggravating asthma – in fact, ozone is one of the most common asthma triggers.
• Inflaming and damaging the cells lining the lungs, much the same way as a sunburn damages the skin cells.
• Aggravating chronic lung diseases such as COPD.
• Making it more difficult for the lungs to fight off infections.
• Causing permanent lung damage in children and adults through repeated short-term exposure.

Often people who are affected by ozone will experience symptoms. But that’s not always the case. Some damage can occur without any noticeable signs, and lung damage can continue to occur even after symptoms go away.

When levels are high, people at risk should take simple precautions:

• Stay indoors as much as possible.
• Limit outside activities to the early morning hours or after sunset. Ozone levels tend to go down with the sun.
• Refrain from exercising or working vigorously outdoors when levels are high.
• Stay away from high traffic areas, and avoid exercising near these areas at all times.
• Carpool or use public transportation to help reduce the amount of harmful emissions in the air that contribute to the production of ozone.
• Avoid using gasoline-powered lawn equipment or other gasoline-powered tools.

Big Differences
The distinction between the two ozone issues — the beneficial ozone layer versus ozone pollution — is extreme. The ozone layer in the stratosphere needs to be protected. By the same token, ozone produced by the effects of sunlight on air pollutants must be reduced.

Controlling air pollution will help solve both of these problems, thereby benefiting our health and well-being.

Reviewed: 09-12-06
Revised: