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Since Ozone is created as a secondary pollutant by the action of sunlight on volatile organic compounds (VOCs) and oxides of nitrogen it is different from most pollutants. A toxic gas, Ozone can cause irreversible damage to the respiratory tract and lung tissue if delivered in high quantities. Asthmatics are known to adopt these symptoms more easily.
Nitrogen oxides consist mainly of nitrogen dioxide (NO2) and nitric oxide (NO). Nitric oxide is more readily emitted into the atmosphere as a primary pollutant, from traffic and power stations, and is often oxidized to form nitrogen dioxide following dispersal. The amount of nitrogen dioxide emitted directly to the atmosphere is relatively small. Nitric oxide is relatively non-toxic, but at high concentrations the health effects include changes to lung function. Nitrogen dioxide, however, is damaging to health, due to its toxicity. Health effects of exposure to nitrogen dioxide include shortness of breath and chest pains.
Transport, tobacco smoke and gas appliances are the major sources of carbon monoxide. When carbon monoxide bonds to hemoglobin, the oxygen carrying component of the blood stream, it forms carboxyhemaglobin (COHb) which can be life-threatening in high doses. The effects of carbon monoxide pollution are more damaging to pregnant women and their fetus. Research into smoking and pregnancy shows that concentrations within the blood stream of unborn infants are as high as 12%, causing retardation of the unborn child�s growth and mental development.
A significant proportion of atmospheric lead comes from traffic emissions, due to the lead content in petrol. This has been significantly reduced in recent years but lead is still a serious air pollutant especially to those living near to areas of dense traffic. Damage to the central nervous system, kidneys and brain can result from high concentrations in the blood. Children, however, exhibit vulnerability to the toxic effects of lead at much lower concentrations than adults. It has been shown that there is a strong link between high lead exposures and impaired intelligence.
Even moderate concentrations of sulfur dioxide may result in impaired lung function in asthmatics. Tightness in the chest and coughing may also result at higher levels. Sulfur dioxide pollution is considered more harmful when particulate and other pollution concentrations are high.
Some VOCs are quite harmful. Benzene, for example, has been linked with an increased susceptibility to leukemia, if exposure is maintained over a long period.
