Effects of air pollution and smoking on chronic obstructive pulmonary disease and bronchial asthma.

Although both tobacco smoking and air pollution are believed to be environmental factors affecting the prevalence of chronic obstructive pulmonary disease (COPD) and bronchial asthma, the mechanisms by which they induce/aggravate these diseases are still not known in detail. While smoking has been demonstrated to cause and aggravate COPD and bronchial asthma, the influence of air pollution, suspected to have hazardous environmental effects since the historical episodes of severe air pollution such as the London Smog, on the prevalence of airway diseases remains unclear. This is due, in part, to changes over time in the nature of the air pollutants concerned. There have been no consistent findings on the effects on airway diseases of air pollutants at levels currently observed in developed countries. It is believed that cessation of smoking is the most important factor in preventing the development of COPD.