Point source sulphur dioxide peaks and hospital presentations for asthma

Objective-To examine the effect on hospital presentations for asthma of brief exposures to sulphur dioxide (SO2) (within the range 0-8700 mu g/m(3)) emanating from two point sources in a remote rural city of 25 000 people. Methods-A time series analysis of SO2 concentrations and hospital presentations for asthma was undertaken at Mount Isa where SO2 is released into the atmosphere by a copper smelter and a lead smelter. The study examined 5 minute block mean SO2 concentrations and daily hospital presentations for asthma, wheeze, or shortness of breath. Generalised linear models and generalised additive models based on a Poisson distribution were applied. Results-There was no evidence of any positive relation between peak SO2 concentrations and hospital presentations or admissions for asthma, wheeze, or shortness of breath. Conclusion-Brief exposures to high concentrations of SO2 emanating from point sources at Mount Isa do not cause sufficiently serious symptoms in asthmatic people to require presentation to hospital.