Asthma and exacerbation of chronic bronchitis: sentinel and environmental data in a time series analysis

To see whether effects of air pollutants and other environmental factors on the respiratory tract can be detected by the Swiss sentinel reporting system, two years' data of asthma bronchiale and exacerbation of chronic bronchitis were analyzed. On average, 16 cases of asthma and 9 cases of bronchitis were reported per week. The respective figures expressed as mean percentages of all consultations were 0.12% and 0.065%. Data of SO2, NO2, ozone and total suspended particles were used to measure air pollution. Additionally, meteorologic parameters such as air temperature and atmospheric pressure were used, as well as the appearance of the most important pollen groups in Switzerland: grass, birch tree and mugwort. Environmental data were summarized using the mean or sum of all measuring stations. Autocorrelations in the time series were accounted for statistically. Our analysis could not establish any relationship between reports of asthma or exacerbation of chronic bronchitis and air pollutants or other environmental data. This result, which is partly contradicted by the literature, could be explained by low numbers of reports due to patient's self administration of medication and an imprecise determination of true exposure.