Manmade air pollution is the cause of more than two million deaths every year, according to a new study.
In a paper published Friday in the journal Environmental Research Letters also said that the changing climate has a minimal, yet negative effect.
The study estimated that 2.1 million people die every year due to fine particular matter (PM2.5) - tiny particles suspended in the air that can penetrate deep into a person's lungs. The increase in PM2.5 has been caused by humans and it is known to cause cancer and other respiratory diseases.
"Our estimates make outdoor air pollution among the most important environmental risk factors for health," University of North Carolina's Jason West, co-author of the study, said in a statement. "Many of these deaths are estimated to occur in East Asia and South Asia, where population is high and air pollution is severe."
The climate change can increase or decrease air pollution. For example, temperature, humidity and rainfall all have an effect on the levels of pollutants in the air.
"Very few studies have attempted to estimate the effects of past climate change on air quality and health. We found that the effects of past climate change are likely to be a very small component of the overall effect of air pollution," West said.
The ozone high in the Earth's atmosphere protects the planet from harmful sunrays, but human-produced ozone on ground level is very damaging. According to the study, manmade ozone is created by industrial activities and their chemical reaction to urban and suburban regions.
For instance, wet climates tend to create less ground-level ozone while dry climates promote harmful ozone. However, the authors of the study could not conclusively say climates have had an effect on air pollution.
"It cannot be clearly concluded that past climate change has increased air pollution mortality," the authors wrote.
The researchers used 14 models of simulated ozone levels and six models of simulated PM2.5 levels. Their conclusion was that multiple models produced varying results.
"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."
