The geographical and biometeorological corralates of childhood asthma morbidity in Tasmania

Environmental aspects of asthma and wheezy breathing have been investigated in three Tasmanian populations; wheezers from the 1968 survey of the 1961 birth cohort, admissions to public hospitals 1972-1977 for asthma and asthmatics from the 1971 birth cohort. Significant spatial clustering was detected in those members of the 1961 cohort defined as suffering from reversible airways obstructions. Geographic concentrations of persons showing respiratory symptoms defined 'good' and 'bad' areas. Such areas differed, indeed were mutually exclusive, for the two sexes. These areas were used as the basis for sampling asthmatics from the 1971 cohort for the purposes of prospective study. Significant clustering was not confined to spatial distributions; hospital admissions over a six year period demonstrated marked temporal variation. The seasonal distribution of attacks differed for males and females and peaks in admissions of either sex were shown to be related to strong weather changes. A prospective study of wheezy breathing in samples of children from the 1971 birth cohort allowed a closer examination of the interaction between reversible airways obstruction and meteorological variables. Study area selection was guided by the spatial analyses of the wheezers from the 1961 cohort. In each area the children kept daily diaries of their wheeziness for nineteen months. The aggregated morbidity series for each area were then examined in relation to daily weather parameters and other atmospheric measurements. Relationships between weather and wheezing were seen to differ between individual times or parts of the series. Major fluctuations in wheeziness were due to the occurrence of certain weather situations. Regression models for each area and sex were constructed to predict wheeziness under various synoptic conditions. With the inclusion of only commonly available weather variables as predictors the level of explanation achieved for certain weather patterns was very high, up to ninety-six per cent. High levels were maintained during tests on new data. During certain weather types, however, wheeziness was low and was poorly predicted by meteorological factors. Risks to asthmatics differed depending upon sex and were localised both in the domains of space and of time. Maps delineated areas of increased risk and regression equations Indicated times of increased risk. Armed with this knowledge, a primary preventive approach could be advocated for the populations at risk