Have the short-term mortality effects of particulate matter air pollution changed in Australia over the period 1993-2007?

•We explore whether the mortality effect of PM10 has changed in Australia over time.•Evidence is found that the effect of PM10 has declined in Brisbane and Sydney.•It is possible that the decline is due to a reduction in the toxicity of PM10.

The author investigates whether the mortality effect of particulate matter air pollution (PM10) has changed in Australia over the period 1993-2007. This period corresponds to an era of increasing Government intervention aimed at improving air quality and, as a result, a potential decrease in the toxicity of PM10. Evidence is found that the mortality effect of PM10 has declined in both Brisbane and Sydney. For Sydney we estimate that the effects of PM10 on total and cardiovascular mortality are, respectively, decreasing at the rate of 10% and 13% annually. We speculate that one possible reason for this decline could be a reduction in the toxicity of PM10. A difference between this study and a similar United States study is that PM10 concentrations have not been declining in Australia. This means that the observed decline in the mortality effect of PM10 is not an artefact of a declining PM10 concentration.