The natural layer of ozone in the upper atmosphere blocks harmful ultraviolet radiation from reaching the earth's surface; but in the lower atmosphere, ozone is a harmful pollutant. Ozone damages lung tissue, and causes particular problems for people with asthma and other lung diseases. Even modest exposure to ozone can cause healthy individuals to experience chest pains, nausea, and pulmonary congestion.
Ground level ozone is the prime ingredient of smog, the pollution that blankets many urban areas especially during the summer months. When inhaled, even at low levels, ozone can cause respiratory problems and aggravate asthma in children, the elderly, those with respiratory diseases, and affect healthy adults who are working or exercising outside on a smoggy day. Children are most at risk from exposure to ozone because they are often active outside in summertime smog. Long-term exposures to ozone may lead to premature aging of the lungs and chronic respiratory illnesses. Ozone also harms the environment by damaging crops, harming sensitive waterways and reducing visibility. Ozone results from the combination in the atmosphere of other pollutants -- primarily volatile organic compounds and nitrogen oxides -- during warmer weather.
Scorching days may bring heavy smog, which can damage the lungs. Everyone is affected by smog, but children and the elderly are the most vulnerable. The following tips help reduce smog and protect health. (a) Heed air quality warnings on news broadcasts. (b) Use public transportation, bicycle, walk or carpool. (c) Keep your car tuned and your tires properly inflated. (d) Make sure your car's air conditioner is not leaking coolant. (e) Do not top off the gas tank; this releases smog-forming pollutants into the air. (f) Try to avoid filling the tank on heavy smog days, or fill up during the cooler morning and evening hours. (g) Avoid aggressive driving. Jackrabbit accelerations (flooring the gas pedal), excessive speed and hauling heavy loads increase emissions and decrease fuel efficiency.
In 1999, the European Commission submitted two proposals for combating ozone pollution. The first of them set ceilings on harmful emissions of several chemical substances which contributed to the formation of ozone, while the second sought to introduce binding threshold values for ground level concentrations of ozone.