Evidence for the implication of environmental factors in the aetiology of chronic bronchitis.

The single most important harmful factor in the aetiology of bronchitis is cigarette smoking, however environmental factors play a significant, if smaller role. Morbidity and mortality due to bronchitis have been higher in Britain than other European countries and the regional variation also suggests environmental influences. There is a marked seasonal variation in the prevalence of bronchitis due to the independent influences of air temperature and air pollution. The relationship between air pollution and bronchitis has been confirmed for both children and adults, and a distinction is made between acute short term and chronic long term effects. In recent years attention has focused on pollution of the microclimate within buildings. Occupational and other social factors may also be of aetiological importance.