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Good Ozone and Bad Ozone

The word "ozone" has prompted a lot of confusion over the past few years. The confusion persists because there is in fact good and bad ozone. The ozone layer in the upper atmosphere is essential because it filters harmful ultraviolet radiation from the sun, reducing the amount reaching the earth’s surface. On the other hand, high accumulations of ozone in the lower atmosphere near ground level can be harmful to people, animals, crops and other materials. The ozone gas in both the upper and lower atmosphere is the same; the difference is that one benefits and one harms. Ground-level ozone is the most pervasive air quality problem in Texas and the nation.

What is Ozone?

Ozone is a form of oxygen with three atoms, instead of the usual two atoms. It is a phytochemical oxidant and, at ground level, is the main component of smog. Ozone is not emitted directly into the air but is formed through chemical reactions between natural and man-made emissions of volatile organic compounds (VOCs) and nitrogen oxides in the presence of sunlight. These gaseous compounds mix like a thin soup in the ambient, or outdoor air, and when they interact with sunlight, ozone is formed. Sources of these pollutants include automobiles, gas-powered motors, refineries, chemical manufacturing plants, solvents used in dry cleaners and paint shops, and wherever natural gas, gasoline, diesel fuel, kerosene and oil are combusted.

Ozone pollution is the periodic increase in the concentration of ozone in the ambient air, the natural air that surrounds us. It is mainly a daytime problem during the summer months because warm temperatures play a role in its formation. When temperatures are high, sunshine is strong, and winds are weak, ozone can accumulate to unhealthful levels.

Ozone Is a Health Hazard

The biggest concern with high ozone concentration is the damage it causes to human health, vegetation and to many common materials we use. High concentrations of ozone can cause shortness of breath, coughing, wheezing, headaches, nausea, eye and throat irritation, and lung damage. People who suffer from lung diseases like bronchitis, pneumonia, emphysema, asthma and colds have even more trouble breathing when the air is polluted. These effects can be worse in anyone who spends significant periods of time exercising or working outdoors. Children often play outside for long periods during the summer. On days when ozone levels are high, children are at increased risk for respiratory problems. While there are many ongoing efforts on the local, state and federal level to reduce ozone-forming pollutants, the county notification system was put in place to provide better information to the school districts.