In: Health24 Nov 2014
Thirty to 40 years ago, any review of factors relating to the development or exacerbation of chronic airways disease (CAD) would have stressed the role of urban air pollution but, as accompanying articles show, the major efforts that have been made to control the principal pollutants have greatly reduced their impact. This is true of the United Kingdom, where chronic bronchitis has been particularly prevalent and where in former decades there were clear indications of associations with exposure to pollution from the burning of coal. By now, however, cigarette smoking has emerged as the dominant factor, determining to a large extent the distribution of CAD between different social classes or different localities. Thus, with respect to the United Kingdom, Holland2 stresses the importance of smoking, adding some reference to indoor pollution, while pointing to the large reductions in outdoor pollution and no longer regarding that as important.
The situation in Japan has been somewhat different in that rapid industrialization in the postwar years led to sharp increases in pollution, particularly by sulfur dioxide from coal or oil burning, followed by strenuous efforts since the 1970s, to reduce emissions again. However, as Aold points out, exposure to such pollution does not appear to have had demonstrable effects on subsequent bronchitis mortality rates, and the prevalence of symptoms has been affected more by other factors, such as histories of acute respiratory illnesses. The report from the United States concentrates on smoking as a determinant of chronic obstructive pulmonary disease (COPD). Concentrations of most pollutants are now well controlled, and the data provided by Higgins do not indicate any substantial role for outdoor air pollutants in the distribution of mortality or morbidity from COPD in the United States. Some recent studies, however, have shown acute effects, such as small transient changes in lung function, that might still be linked with air pollution. cheap-asthma-inhalers.com
Even in China, where the continuing widespread use of coal for domestic and industrial purposes leads to much pollution in urban areas, the data presented show the predominant importance of smoking, with indoor pollution in the home or workplace as an additional contributory factor rather than general outdoor pollution.
Overall, it is clear that the situation has changed: no longer is general outdoor air pollution an all-pervading influence, to which people in urban areas are sufficiently exposed to allow associations to be demonstrated between respiratory disease rates in different localities and corresponding average levels of pollution. Rather, it is a question of examining the microenvironment of individuals to determine whether some persons experience effects from inhaled pollutants, in addition to the clear-cut contribution from active smoking, with indoor pollutants needing to be considered more than those outdoors. In this article, the characteristics of different types of air pollutants are considered, and an attempt is made to develop a coherent role for air pollution of various lands in the gradual development of CAD.
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