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There are no reported studies on the effects of ambient air pollution on emergency department (ED) attendances in Sydney, Australia. This study aimed to determine associations between ambient air pollutants and ED attendances for cardiovascular disease (CVD) in those aged 65+ years. We constructed daily time series of hospital ED attendances, air pollutants and meteorological factors for the Sydney metropolitan area from 1 January 1997 to 31 December 2001. We used generalised linear models to determine associations between daily air pollution and daily ED attendances and controlled for the effects of long-term trends, seasonality, weather and other potential confounders. Increased ED attendances for all CVD, cardiac disease and ischaemic heart disease were seen with 24-h particulate pollution, 1-h NO(2), 8-h CO and 24-h SO(2). Air pollutants were associated with decreased ED attendances for stroke. The effects of air pollutants on CVD, cardiac disease and stroke attendances were generally greater in the cool period compared to the warm period. The single-pollutant effects of CO, O(3), NO(2) and SO(2) were essentially unchanged in two-pollutant models. Although air pollution levels in Sydney are relatively low compared to similar cities, we have demonstrated associations between ambient air pollutants and ED attendances for CVD in people aged 65+ years. Our study adds to the growing evidence for the effects of ambient air pollution on CVD outcomes even at relatively low ambient concentrations.

Background: The effect of individual pollutants and the period(s) during pregnancy when pollutant levels are likely to have most impact on preterm birth is not clear. We evaluated the effect of prenatal exposure to six common urban air pollutants in the Sydney metropolitan area on preterm birth. Methods: We obtained information on all births in metropolitan Sydney between January 1, 1998 and December 31, 2000. For each birth, exposure to each air pollutant was estimated for the first trimester, the three months preceding birth, the first month after the estimated date of conception and the month prior to delivery. Gestational age was analysed as a categorical variable in logistic regression models. Results: There were 123 840 singleton births in Sydney in 1998-2000 and 4.9% were preterm. Preterm birth was significantly associated with maternal age, maternal smoking, male infant, indigenous status and first pregnancy. Air pollutant levels in the month and three months preceding birth had no significant effect on preterm birth after adjusting for maternal and infant covariates. Ozone levels in the first trimester of pregnancy and spring months of conception and sulphur dioxide were associated with increased risks for preterm births. Nitrogen dioxide was associated with a decreased risk of preterm births. Conclusion: We found more protective than harmful associations between ambient air pollutants and preterm births with most associations non-significant. In view of these inconsistent associations, it is important to interpret the harmful effects with caution. If our results are confirmed by future studies then it will be imperative to reduce Sydney's already low air pollution levels even further. [ABSTRACT FROM AUTHOR]

OBJECTIVES: This study examined the effects of outdoor air pollutants in Sydney, Australia, on daily mortality. METHODS: Time-series analysis was performed on counts of daily mortality and major outdoor air pollutants (particulates, ozone, and nitrogen dioxide) in Sydney (1989 to 1993) with adjustment for seasonal and cyclical factors. Poisson regression was calculated with allowance for overdispersion and autocorrelation. The effects of lagging exposure by 0 to 2 days were assessed with single- and multiple-pollutant models. RESULTS: An increase in daily mean particulate concentration from the 10th to the 90th centile was associated with an increase of 2.63% (95% confidence interval 0.87 to 4.41) in all-cause mortality and 2.68% (0.25 to 5.16) in cardiovascular mortality. An increase in daily maximum 1-hour ozone concentration from the 10th to the 90th centile was associated with an increase of 2.04% (0.37 to 3.73) in all-cause mortality and 2.52% (-0.25 to 5.38) in cardiovascular mortality. An increase in the daily mean nitrogen dioxide concentration from the 10th to the 90th centile was associated with an increase of 7.71% (-0.34 to 16.40) in respiratory mortality. Multiple-pollutant models suggest that the effects of particulates and ozone on all-cause and cardiovascular mortality, and of nitrogen dioxide on respiratory mortality, are independent of the effects of the other pollutants. CONCLUSIONS: Current levels of air pollution in Sydney are associated with daily mortality. [ABSTRACT FROM AUTHOR]

A response by Geoffrey Morgan, Stephen Corbett, John Wlodarczyk and Peter Lewis to a letter to the editor about their article on the toxic effects of air pollution and mortality is presented.