Bushfire smoke: an exemplar of coupled human and natural systems

Carbon-based microscopic particles have provided a crucial line of evidence in understanding the coupling between humans and fires. Through the sedimentary record, they have informed our understandings of the patterns of climate and humans on fire activity through time. The extent of contemporary atmospheric biomass burning emissions has become apparent through satellite monitoring, motivated by concerns about the effect on the climate system. Sophisticated monitoring techniques designed to monitor industrial pollution have provided a data stream useful to determine the impacts on human health of wildfire smoke: we review this rapidly expanding field. The key findings are that biomass smoke is quantitatively and qualitatively different from urban air pollution and that there is no ‘safe’ level of biomass smoke exposure. Managing fires and smoke impacts will become increasingly challenging as the climate continues to warm and demands understanding the trade-off between wildfire and planned burns. The health impacts from severe smoke events are substantial when large populations are affected resulting in measurable increases in illness, hospital admissions, and deaths. The health impacts are not evenly distributed, and large segments of the population fall into higher risk groups. People in these categories are also likely to be adversely affected by the comparatively minor episodes of pollution generated by smaller planned burns. Planned burns thus need active programmes of public communication and air quality monitoring to ensure that the overall public health benefits of the intervention can be achieved with the minimum possible adverse impacts on higher risk individuals.