China has the world's deadliest pollution, but just how bad is it?

An alarming new study reveals that the country's poor air quality is taking years off people's lives — 3.5 years on average, to be exact.

The average is even higher in China's northeasten cities — which experience some of the worst pollution, particularly in the winter — with Tianjin topping the list at 7.1 years. (Shanghai clocked in at 5.5 years). Here's how China's killer smog impacted average life expectancy in the country's 50 most populated prefectures, according to the study conducted by the Energy Policy Institute at the University of Chicago:

Images via Energy Policy Institute at the University of Chicago

The analysis calculated how much life expectancy would rise around the world if countries met World Health Organization (WHO) standards for safe air quality. The report estimates that 4.5 billion people around the world breathe air containing particulate levels far in excess of WHO's safety limits. Here's what the data looks like globally; darker areas on the map represent places with a larger estimated decrease in average life expectancy:

Images via Energy Policy Institute at the University of Chicago

These particulates, PM10 and PM2.5, are mostly a byproduct of fuel consumption, with cars, coal-burning power plants and waste burning facilities among the worst offenders. 

PM2.5 pollutants pose the biggest health risk as their incredibly small particulates enter the lungs and eventually the blood stream. This means that they pose a risk not only for respiratory, but also for cardiovascular diseases. These diseases include strokes, lung-cancer and ischaemic heart disease.

A separate study released by the Proceedings of the National Academy of Sciences (PNAS) also revealed how China's approach towards coal-powered heating in the winter affects lifespans across the country. The study revealed that the "Huai River Policy," which was intended to provide free coal heating to all cities north of the geographical dividing line between northern and southern China (the Huai River-Qin Mountains Line), unintentionally causes people in northern China to have life expectancies 3.1 years lower than people in the south.

Beijing has vowed to decrease pollution in the capital by 15 percent this winter, with a public construction ban expected to go into effect from November to March of next year. But winter pollution is still expected to be worse than usual this year.

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