Air pollution and other local factors in respiratory disease

摘要

Respiratory sickness and death rates obtained from various sources have been related to indices of air pollution and other urban characteristics in different areas of the United Kingdom. Sickness absence data, derived from a survey among civil servants, allowed comparisons between outdoor postmen and indoor male office workers, and between men and women doing the same work in the same indoor environment. Attack rates from four major types of respiratory illness have been calculated in these groups for 37 urban and rural areas of the United Kingdom. From routinely collected data on the experience of postmen, the rates for death and permanent disablement from chronic bronchitis and the total time lost through sickness have been calculated for the same areas. These Civil Service data have been collated with death rates from bronchitis, pneumonia, pulmonary tuberculosis, cancer of the lung and influenza among the general middle-aged population (45-64 years) of both sexes in these 37 areas over the same period. Both mortality and morbidity rates have been correlated with three indices of local environment: frequency of fog, number of persons per acre and percentage of persons living more than two to a room. The trends with age and with fog frequency in the respiratory attack rates have also been examined. Analysis of the material suggests that, apart from general influences affecting sickness absence, such as group morale or the "men-opausal peak", environmental factors influence the distribution of respiratory disease in the populations surveyed. Severe bronchitis causing permanent disablement and death among postmen exposed by their job to atmospheric conditions is uniquely related to the frequency of fog, and, presumably, to the level of air pollution. These rates in a group whose job and pay are uniform throughout the country run parallel to local bronchitis death rates in middle age. Variations in the latter are not related to population density or to domestic overcrowding, and may thus result from a specific effect of air pollution on respiratory disease. The high incidence of influenza morbidity and tuberculosis mortality in areas with much domestic overcrowding emphasises the importance of cross-infection in the home. Some of the excessive urban mortality from pulmonary tuberculosis and pneumonia may also be due to increased opportunities for infection; but the singular association of lung cancer mortality with population density and not with the fog index of air pollution suggests that urban-rural differences in smoking habits may have affected the risk of death from three major causes of respiratory mortality: lung cancer, pulmonary tuberculosis and, perhaps, pneumonia. The relevance of smoking habits to bronchitis could not be assessed from the available data.