This kind of uncontrolled burning results in significant emissions of small particles (PM2.5) and toxic gases. Exposure to these small particles increases the risk of stroke, heart disease, lung cancer and respiratory disorders.

Previous work has shown that open burning of household waste releases around 10 Teragrams of PM2.5 per year, and that the countries with the largest emissions from burning include China, India, Brazil, Mexico, Pakistan and Turkey.

Using the GEOS-Chem global chemical-transport model, John Kodros from Colorado State University, US, and his colleagues estimated the number of premature adult deaths from exposure to burning of household waste. Their model suggests that 270,000 premature deaths are caused by exposure to the smoke from this uncontrolled burning – equating to 9% of the deaths linked to PM2.5.

"We find the countries with the largest mortalities from waste combustion are China, India, Pakistan and Russia," said Kodros, whose findings are published in Environmental Research Letters (ERL). "These countries have both high emissions and high population density."

However, Kodros also cautions that uncertainty in the health response to PM2.5 and in the concentration of PM2.5 released by waste burning means that the total number of deaths could be anywhere between 138,000 and 518,000 per year.

In locations where open burning of waste is common, it increases average PM2.5 concentrations by 10 to 20% and is comparable to the particulate pollution released by outdoor cookstoves. "Both sources tend to be concentrated in developing countries, where there is a lack in infrastructure either for reliable access to electricity or waste removal," explained Kodros.

Sometimes the countries lying downwind suffer too. By comparing the difference between estimated emissions and mortality estimates, Kodros and his colleagues show that several European countries, including Switzerland, Austria and Belgium, as well as South Korea and Japan, have elevated mortality rates despite low rates of waste burning.

Waste burning also emits a number of toxic gases that may have additional negative health implications that are harder to estimate. "This means that the net health impacts from waste combustion could be greater than estimates for only PM2.5," said Kodros.

Until now, municipal waste collections and controlled disposal of residential waste have failed to be a priority for many countries, but this research suggests that they could save many lives.

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