Abstract
BackgroundSevere air pollution generated by forest fires is becoming an increasingly frequent public health management problem. We measured the association between forest fire smoke events and hospital emergency department (ED) attendances in Sydney from 1996–2007.MethodsA smoke event occurred when forest fires caused the daily citywide average concentration of particulate matter (PM10 or PM2.5) to exceed the 99th percentile of the entire study period. We used a time-stratified case-crossover design and conditional logistic regression models adjusted for meteorology, influenza epidemics, and holidays to estimate odds ratios (OR) and 95% confidence intervals (CI) for ED attendances on event days compared with non-event days for all non-trauma ED attendances and selected cardiorespiratory conditions.ResultsThe 46 validated fire smoke event days during the study period were associated with same day increases in ED attendances for all non-trauma conditions (1.03, 95% CI 1.02, 1.04), respiratory conditions (OR 1.07, 95% CI 1.04, 1.10), asthma (OR 1.23, 95% CI 1.15, 1.30), and chronic obstructive pulmonary disease (OR 1.12, 95% CI 1.02, 1.24). Positive associations persisted for one to three days after the event. Ischaemic heart disease ED attendances were increased at a lag of two days (OR 1.07, 95% CI 1.01, 1.15) while arrhythmias had an inverse association at a lag of two days (OR 0.91, 95% CI 0.83, 0.99). In age-specific analyses, no associations present in children less than 15 years of age for any outcome, although a non-significant trend towards a positive association was seen with childhood asthma. A further association between smoke event and heart failure attendances was present for the 15–65 year age group, but not older adults at a lag of two days (OR 1.37 95% CI 1.05, 1.78).ConclusionSmoke events were associated with an immediate increase in presentations for respiratory conditions and a lagged increase in attendances for ischaemic heart disease and heart failure. Respiratory impacts were either absent or considerably attenuated in those <15 years. Similar to previous studies we found inconsistent associations between fire smoke and cardiovascular diseases. Better characterisation of the spectrum of population health risks is needed to guide public heath responses to severe smoke events as this exposure becomes increasingly common with global climate changeElectronic supplementary materialThe online version of this article (doi:10.1186/1476-069X-13-105) contains supplementary material, which is available to authorized users.
Highlights
Severe air pollution generated by forest fires across the globe is becoming an increasingly frequent public health management problem
Days affected by forest fire smoke were warmer than other days, while humidity was similar on smoke days and non-smoke days (Table 2)
Over the same period there were more than 630,000 emergency department (ED) presentations by Sydney residents for respiratory conditions and close to 370,000 presentations for cardiovascular conditions (Table 3)
Summary
Severe air pollution generated by forest fires across the globe is becoming an increasingly frequent public health management problem. As climate change increases the conditions favourable to severe fires [1], populations living in fire prone areas, are expanding, especially at the urban fringes [2] and more deliberate landscape burning is being conducted to protect property and infrastructure from extreme events [3,4]. There is a comparatively small body of public health evidence addressing the health impacts of severe forest fire smoke events. Urban particulate air pollution and forest fire smoke have different compositions, and different durations and severities of exposure. Severe air pollution generated by forest fires is becoming an increasingly frequent public health management problem.
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