El Niño years increase the incidence of landscape fires, resulting in an additional 200 days per year when atmospheric particle targets are exceeded and increase adult mortality by about two per cent. The findings, reported this week in Nature Climate Change, have implications for global public health.

Miriam Marlier and colleagues use satellite-derived fire estimates and atmospheric modelling to quantify health effects of regional land fires in southeast Asia between 1997 and 2006. They show that the fire emissions for El Niño years in that period repeatedly exposed up to 11% of the population to atmospheric particles and ozone levels above the World Health Organization’s interim targets. The authors suggest that reducing regional deforestation and degradation — and thereby forest fires caused by land-use change — would therefore improve public health.