MAINZ, Germany, Sept. 17 (UPI) -- Every year, more than 3.3 million people worldwide die prematurely as a result of air pollution.
That's according to researchers at the Max Planck Institute for Chemistry, who, in a new study, extrapolated the health consequences of growing worldwide emissions.
Scientists focused on the most damaging of air pollutants, primarily particulates with a diameter of less than 2.5 micrometres. Where air quality monitoring data wasn't available, researchers used models to predict pollution levels. They combined their totals with epidemiological data to estimate the detrimental effects of particle pollution on human health.
"We know rather well from statistical epidemiological studies in Europe and the US with several hundred thousand participants how specific pollutant concentrations affect mortality rates," researcher Johannes Lelieveld said in a press release.
Lelieveld is the lead author of the new study, published this week in the journal Nature.
As similar regional studies have shown, particulates do most of their damage by boosting the risk of heart attack and stroke among polluted populations. After vascular risks, pulmonary problems are the next most likely. Air pollution has been consistently linked with higher rates of lung cancer and other respiratory issues.
While pollution levels have been steadily curbed in the U.S. and Europe, particulate pollution is on the rise across much of Asia. Of the 3.3 million annual deaths, China is responsible for 1.4 million. Air pollution in India kills roughly 650,000 people.
Surprisingly, when researchers looked at which sources of pollution were most deadly, they found the particulates emitted by agricultural and domestic fires -- primarily pesticide use and trash burning -- are disproportionately deadly.
"It is generally assumed that industry and transport are the worst air polluters. But that is evidently not the case on a global scale," explained Lelieveld. "Although these are low-key activities, they add up, particularly if the majority of the population uses them."
The problem of domestic fires are largely concentrated in Asia and Africa. In the West, fertilizers are especially damaging. Large-scale farming and livestock operations are responsible for combinations of ammonium sulphate and ammonium nitrate escaping into the atmosphere, where these pollutants form deadly particulates.
Worldwide agriculture accounts for one-fifth of all air-pollution-related premature deaths.