Respiratory symptoms, atopy, and bronchial reactivity were measured in primary school children living in Lake Munmorah (LM), a coastal town near two power stations, and in Nelson Bay (NB), a coastal town free from any possible major sources of outdoor air pollution. A prevalence survey and longitudinal follow-up study were performed 1 year apart. In both studies, the prevalence of ever wheezed, current wheezing, breathlessness, wheezing with exercise, diagnosed asthma, and use of drugs for asthma at LM were all approximately double the prevalence at NB (all P values less than 0.01). The prevalence of bronchial reactivity was significantly greater at LM than NB (P less than 0.01) at the first but not the second survey. By contrast, no significant differences were found between the two areas for skin test atopy or for parental history of allergic disease. Multivariate analysis supported the conclusion from the univariate analysis that there was more wheezing at LM compared to NB at both studies, when adjusted for atopy, smoking in the home, age, and sex. As expected, a positive skin test reaction to house dust mite was the predominant explanatory variable. Asthma was more common in the community near power stations (LM) than in the NB area. The absence of significant differences in skin test atopy and parental history of allergic disease argued against major genetic differences between the two groups. By contrast, the more common reporting of siblings' chest disease and asthma in Lake Munmorah supported an environmental cause.

To assess longitudinally the effect of living in the vicinity of coal-fired power stations on children with asthma, 99 schoolchildren with a history of wheezing in the previous 12 months were studied for 1 year, using daily diaries and measurements of air quality. The children had been identified in a cross-sectional survey of two coastal areas: Lake Munmorah (LM), within 5 km of two power stations, and Nelson Bay (NB), free from major industry. Daily air quality [sulphur dioxide (SO2) and nitrogen oxides (NOx)], respiratory symptoms, and treatment for asthma were recorded throughout the year. Measurements of SO2 and NOx at LM were well within recommended guidelines although they were several times higher than at NB: maximum daily levels in SO2 (micrograms/m3) were 26 at LM, 11 at NB (standard, 365); yearly average SO2 was 2 at LM, 0.3 at NB (standard, 60); yearly average NOx (micrograms/m3) was 2 at LM, 0.4 at NB (standard, 94). Marked weekly fluctuations occurred in the prevalence of cough, wheezing, and breathlessness, without any substantial differences between LM and NB. Overall, the prevalence of symptoms was low (10% for wheezing, 20% for any symptom). Whether the daily SO2 and NOx levels affected the occurrence of respiratory symptoms was investigated in children at LM using a logistic regression (Korn and Whittemore technique). For these children as a group, air quality measurements were not associated with the occurrence of symptoms.