Air pollution is killing about 4,000 people in China a day, accounting for one in six premature deaths in the world's most populous country, a study has found. Physicists at the University of California, Berkeley, calculated that about 1.6 million people in China die every year from heart and lung problems and strokes because of incredibly polluted air, mainly from small particles. Earlier studies put China's annual air pollution death toll at one to two million, but this is the first to use newly released Chinese air monitoring figures. The study 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 computer model calculations that estimate heart, lung and stroke deaths for different types of pollutants. The study's lead author, Dr Robert Rohde, said 38 per cent of China's population lived in an area with a long-term air quality average that the US Environmental Protection Agency (EPA) called unhealthy. "It's a very big number," he 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 China's air pollution in perspective, the most recent American Lung Association data shows the city of 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. READ MORE: China's ability to tackle air pollution doubtful, says veteran US policymaker The EPA estimated five years ago that 63,000 to 88,000 people died in the US each year from air pollution. Other estimates range from 35,000 to 200,000. Unlike the US, air pollution in China was worst in winter because coal was burned to heat homes and weather conditions kept dirty air closer to the ground, Rohde said. Beijing will host the 2022 Winter Olympics. Other scientists praised the research, including Dr Jason West, of the University of North Carolina, who said he expected it to prove widely influential. READ MORE: Air pollution is bigger killer in China than smoking, says new Greenpeace study As China started to clean up its air, limiting coal use, it would also reduce emissions of carbon dioxide, the chief global warming gas, Rohde said.