China air pollution

The air in Beijing is so polluted that breathing it does as much damage to the lungs as smoking 40 cigarettes a day.

More than 80 percent of Chinese people are regularly exposed to pollution that far exceeds levels deemed safe by the U.S. Environmental Protection Agency.

The report said air pollution in China kills about 4,000 people every day, about 17 percent of all deaths in China, but noted that connecting mortality to pollution is "complicated." The researchers adopted the methods for showing such associations from the WHO Global Burden of Disease study.

The sensors used in the study measure several types of pollution in China: ozone, carbon dioxide, nitrogen oxides and others. One of the most dangerous pollutants is PM2.5, which stands for particulate matter that is smaller than 2.5 microns in diameter. These small particles can enter deep into the human respiratory system, and are associated with a range of harmful or even deadly diseases.

"When I was last in Beijing, pollution was at the hazardous level; every hour of exposure reduced my life expectancy by 20 minutes," said Richard Muller, scientific director of Berkeley Earth and one of the paper's coauthors, in a press release. "It's as if every man, women and child smoked 1.5 cigarettes each hour."

Indeed, Chinese pollution has become such a problem, it has actually become an unexpected moneymaker for some large companies. Facemasks in particular have become a good business for companies