Air pollution events from forest fires and emergency department attendances in Sydney, Australia 1996–2007: a case-crossover analysis

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.

Health impacts of bushfire smoke exposure in Australia

“…A validated database used to distinguish days with high pollution resulting from LFS was used in two Sydney‐based studies to characterize the impacts of specific ‘event’ days rather than incremental pollutant increases . Studies which compared impacts of background airborne particulate matter (PM) to that arising from fires (PM LFS ) found the latter to be associated with higher respiratory risk estimates, raising the potential for a differing or greater magnitude of cellular responses arising from the specific chemical composition unique to the particles in LFS.…”

Mapping Modeled Exposure of Wildland Fire Smoke for Human Health Studies in California

“…A national study showed via principal component analyses that several vulnerability factors similar to those for general air pollution were relevant for fire-PM 2.5 ; specifically, factors included age (e.g., those >65 years); adults with respiratory disease (e.g., COPD and asthma); adults with hypertension, obesity and diabetes; children with asthma; and economic deprivation [35]. Age may also be a factor contributing to a population's susceptibility [36][37][38][39][40].…”

Emissions of trace gases from Australian temperate forest fires: emission factors and dependence on modified combustion efficiency

“…These fires can be intense enough to create pyro-convective lofting and inject smoke at high altitudes (Fromm et al, 2006;Dirksen et al, 2009;Guan et al, 2010) and are expected to become more frequent under a 15 changing climate (Bradstock et al, 2009;Cai et al, 2009;Keywood et al, 2013;King et al, 2013). There has been growing interest in characterising the composition of smoke from Australian temperate forest fires in recent years, mostly arising from increased awareness of the significant impacts of bushfire smoke on regional air quality (Reisen et al, 2011(Reisen et al, , 2013Price et al, 2012;Keywood et al, 2015;Rea et al, 2016) and its associated repercussions on human health (Reisen and Brown, 2006;Johnston et al, 2012Johnston et al, , 2014Reisen et al, 2015;Reid et al, 2016), coincident with a mandate for state agencies to increase 20 prescribed burning in the wake of the catastrophic 2009 forest fires in Victoria (Teague et al, 2010). Prescribed burning is widely used in Australia as a means of reducing bushfire risk (Boer et al, 2009); however, these low to moderate intensity fires often take place close to population centres, under weather conditions that are conducive to pollution build up, sometimes on a regional scale (e.g., Williamson et al, 2016, Fig.…”