Health effects of the September 2009 dust storm in Sydney, Australia: did emergency department visits and hospital admissions increase?

Background: During September 2009, a large dust storm was experienced in Sydney, New South Wales, Australia. Extremely high levels of particulate matter were recorded, with daily average levels of coarse matter (< 10 mu m) peaking over 11,000 mu g/m(3) and fine (< 2.5 mu m) over 1,600 mu g/m(3). We conducted an analysis to determine whether the dust storm was associated with increases in all-cause, cardiovascular, respiratory and asthma-related emergency department presentations and hospital admissions. Methods: We used distributed-lag Poisson generalized models to analyse the emergency department presentations and hospital admissions adjusted for pollutants, humidity, temperature and day of week and seasonal effects to obtain estimates of relative risks associated with the dust storm. Results: The dust storm period was associated with large increases in asthma emergency department visits (relative risk 1.23, 95% confidence interval 1.10-1.38, p < 0.01), and to a lesser extent, all emergency department visits (relative risk 1.04, 95% confidence interval 1.03-1.06, p < 0.01) and respiratory emergency department visits (relative risk 1.20, 95% confidence interval 1.15-1.26, p < 0.01). There was no significant increase in cardiovascular emergency department visits (p = 0.09) or hospital admissions for any reason. Age-specific analyses showed the dust storm was associated with increases in all-cause and respiratory emergency department visits in the = 65 year age group; the <= 5 year group had higher risks of all-cause, respiratory and asthma-related emergency department presentations. Conclusions: We recommend public health measures, especially targeting asthmatics, should be implemented during future dust storm events.