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 micrograms/m3) 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.