About two million people die due to air pollution, a new study reported. The deaths are attributed to a rise in the levels of fine particulate matter (PM2.5), which can penetrate deep into vital organs such as lungs and increase risk of cancer and other respiratory diseases.

A recent study had shown that the rise in pollution in China has led to lower life expectancy in the region. Also, even low levels of air pollution (carbon dioxide and particulate matter) in Europe have been associated with increased risk of lung cancers and heart diseases.

The present study had also found that human-caused increases in ozone has led to  470,000 deaths.

 "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," said Jason West, from the University of North Carolina, co-author of the study.

In the study, researchers used many climate models to re-create the concentrations of ozone and particulate matter in the years 1850 and 2000.

Data from previous epidemiological studies was then used to see how ozone and particulate levels contributed to global mortality rates.

Past research on the subject assumed that climate change would worsen air pollution levels. However, researchers in the current study found that climate change had only a small role to play in deaths related with air pollution.

Difference in temperature and humidity can affect the reaction rates of a pollutant while rainfall may determine whether the pollutant gets accumulated in the environment or not, according to the researchers.

"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," added West, according to a press release.

The study is published in the journal Environmental Research Letters.