Wildfire smoke, fire management and human health

Burning landscapes under controlled conditions to reduce the risk of wildfires is a controversial land management practice. The health risks of smoke generated from controlled burning relative to wildfire remain uncertain. Recent work in the Australian monsoon tropics provided a unique opportunity to study the health effects of smoke pollution at and well below national air quality standards. It found that for each increase in the atmospheric mass of particles 10 μg or less in aerodynamic diameter (PM10) per cubic meter of air per 24-hour period, there was a 26% increase in daily asthma presentations to the emergency department of the Royal Darwin Hospital, with an apparent threshold at 40 μg/m3 PM10 (lower than the Australian PM10 air quality standard of 50 μg/m3). This finding was unaffected by adjusting for weekly rates of influenza, weekday vs. weekends, and school holiday periods. Although further research is being undertaken to substantiate these findings, the upshot of the study suggests that for airsheds containing large human populations, fire managers should strive to keep smoke pollution less than 40 μg/m3 PM10.