Two million 'air pollution' deaths
More than two million deaths occur globally each year as a direct result of air pollution from human activity, scientists have said.
But climate change has only made a small contribution to the lethal effects, it is claimed.
A new study suggests that 2.1 million people die after inhaling fine sooty particles called PM 2.5s generated by diesel engines, power plants and coal fires.
Another 470,000 are thought to be killed by high levels of ozone, created when vehicle exhaust gases react with oxygen.
Dr Jason West, from the University of North Carolina in the US, said: "Our estimates make outdoor air pollution among the most important environmental risk factors for health.
"Many of these deaths are estimated to occur in East Asia and South Asia, where population is high and air pollution is severe."
Climate change since 1850 only led to 1,500 extra deaths from ozone and 2,200 from PM2.5 particulates, according to the research.
The scientists used an ensemble of climate computer models to simulate concentrations of ozone and PM2.5s in the years 2000 and 1850.
Epidemiological studies were then used to assess how the levels related to worldwide death rates.
The findings appear in the Institute of Physics journal Environmental Research Letters.