Air pollution claims more than 2 million lives worldwide every year, according to a new study. And roughly 470 000 deaths occur each year due to increases in ozone caused by humans, the study authors said.
On the other hand, climate change only has a minimal effect on air pollution and rising death rates, the authors concluded.
Researchers from the University of North Carolina estimated that about 2.1 million people die as a result of a surge in fine particulate matter air pollution. These tiny air particles can penetrate deep into the lungs and cause cancer and other respiratory illnesses.
Big health risk
"Our estimates make outdoor air pollution among the most important environmental risk factors for health," study co-author Jason West, of the University of North Carolina, said. "Many of these deaths are estimated to occur in East Asia and South Asia, where population is high and air pollution is severe."
In conducting the study, the researchers simulated the concentrations of ozone and fine particulate matter air pollution in 1850, when the industrial era began, and in the year 2000. The study used 14 different climate models to simulate levels of ozone and another six to simulate fine particulate matter caused by humans.
"We have also found that there is significant uncertainty based on the spread among different atmospheric models," West said. "This would caution against using a single model in the future, as some studies have done."
The researchers also examined previous epidemiological studies to determine how concentrations of air pollution relate to death rates around the world.
The study, in the journal Environmental Research Letters, showed that although climate changes may worsen the effects of air pollution, they do not significantly increase death rates. Climate changes have resulted in 1 500 deaths due to ozone and 2 200 deaths resulting from fine particulate matter air pollution every year.
Climate change can affect air pollution in many ways, the researchers said. For example, rainfall can determine when pollutants accumulate. Rising temperatures can increase the emissions of organic compounds from trees, which react in the atmosphere and form ozone and fine particulate matter.
"Very few studies have attempted to estimate the effects of past climate change on air quality and health," West said. "We found that the effects of past climate change are likely to be a very small component of the overall effect of air pollution."
Visit the US Environmental Protection Agency to learn more about air pollution.