El Niño and health risks from landscape fire emissions in southeast Asia

Emissions from landscape fires affect both climate and air quality. This study uses satellite-derived fire estimates and atmospheric modelling to quantify the effects on health from fire emissions in southeast Asia from 1997 to 2006. Strong El Nino years are found to increase the incidence of fires, in addition to those caused by anthropogenic land use change, leading to an additional 200 days per year when the WHO atmospheric particle target is exceeded and increase adult mortality by 2%. Reducing regional deforestation and degradation, and thereby forest fires caused by land use change would therefore improve public health. Emissions from landscape fires affect both climate and air quality1. Here, we combine satellite-derived fire estimates and atmospheric modelling to quantify health effects from fire emissions in southeast Asia from 1997 to 2006. This region has large interannual variability in fire activity owing to coupling between El Niño-induced droughts and anthropogenic land-use change2,3. We show that during strong El Niño years, fires contribute up to 200 μg m−3 and 50 ppb in annual average fine particulate matter (PM2.5) and ozone surface concentrations near fire sources, respectively. This corresponds to a fire contribution of 200 additional days per year that exceed the World Health Organization 50 μg m−3 24-hr PM2.5 interim target4 and an estimated 10,800 (6,800–14,300)-person (∼ 2%) annual increase in regional adult cardiovascular mortality. Our results indicate that reducing regional deforestation and degradation fires would improve public health along with widely established benefits from reducing carbon emissions, preserving biodiversity and maintaining ecosystem services.