Air pollution is killing about 4000 people in China a day, accounting for one in six premature deaths in the world's most populous country, a new study finds.

Physicists at the University of California, Berkeley, calculated that about 1.6 million people in China die each year from heart, lung and stroke problems because of incredibly polluted air, especially small particles of haze.

Earlier studies put the annual Chinese air pollution death toll at one to two million, but this is the first to use newly released Chinese air monitoring figures.

The study released on Thursday blamed emissions from the burning of coal, both for electricity and heating homes.

The study, to be published in the journal PLOS One, uses real air measurements and then computer model calculations that estimate heart, lung and stroke deaths for different types of pollutants.

Study lead author Robert Rohde said that 38 per cent of the Chinese population lives in an area with a long-term air quality average that the US Environmental Protection Agency calls "unhealthy".

"It's a very big number," Rohde said. "It's a little hard to wrap your mind around the numbers. Some of the worst in China is to the southwest of Beijing."

To put Chinese air pollution in perspective, the most recent American Lung Association data shows that Madera, California, has the highest annual average for small particles in the United States. But 99.9 per cent of the eastern half of China has a higher annual average for small particle haze than Madera, Rohde said.

"In other words, nearly everyone in China experiences air that is worse for particulates than the worst air in the US," Rohde said.