BEIJING -- Outdoor air pollution contributes to the deaths of an estimated 1.6 million people in China every year, or about 4,400 people a day, according to a newly released scientific paper.
Earlier studies put the annual Chinese air-pollution death toll at 1 million to 2 million, but this is the first to use newly released Chinese air-monitoring figures.
The paper maps the geographic sources of China's toxic air and concludes that much of the smog that routinely shrouds Beijing comes from emissions in a distant industrial zone, a finding that may complicate the government's efforts to clean up the capital city's air in time for the 2022 Winter Olympics.
The authors are members of Berkeley Earth, a nonprofit research organization based in Berkeley, Calif., that uses statistical techniques to analyze environmental issues.
The group's paper has been accepted for publication in the peer-reviewed scientific journal PLOS One, according to the organization.
According to the data presented in the paper, about 38 percent of the Chinese population breathes air that would be rated "unhealthy" by U.S. standards. The most dangerous of the pollutants studied were fine airborne particles that can find their way deep into human lungs, be absorbed into the bloodstream and cause a host of health problems, including asthma, strokes, lung cancer and heart attacks.
"It's a very big number," Robert Rohde, the study's lead author, said Thursday. "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, Calif., has the highest annual average for small particles in the United States. But 99.9 percent 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 U.S.," said Rohde.
In a 2010 document, the Environmental Protection Agency estimated between 63,000 and 88,000 people die in the U.S. from air pollution. Other estimates range from 35,000 to 200,000.
The researchers analyzed four months' worth of hourly readings taken at 1,500 ground stations in mainland China, Taiwan and other countries in the region, including South Korea. The group said it was publishing the raw data so other researchers could use it to perform their own studies.
Berkeley Earth's analysis is consistent with earlier indications that China has not been able to tackle its air-pollution problems. Greenpeace East Asia found in April that, of 360 cities in China, more than 90 percent failed to meet national air-quality standards in the first three months of 2015.
The Berkeley Earth paper's findings present data saying air pollution contributes to 17 percent of all deaths in the nation each year. The group says its mortality estimates are based on a World Health Organization framework for projecting death rates from five diseases known to be associated with exposure to various levels of fine-particulate pollution. The authors calculate that the annual toll is 95 percent likely to fall between 700,000 and 2.2 million deaths, and their estimate of 1.6 million a year is the midpoint of that range.
Much of China's air pollution comes from the large-scale burning of coal. Using pollution measurements and wind patterns, the researchers concluded much of the smog afflicting Beijing came not from sources in the city but rather from coal-burning factories 200 miles southwest in Shijiazhuang, the capital of the Hebei province and a major industrial hub.
Promises to clean up Beijing's air were a centerpiece of the nation's bid to host the 2022 Winter Olympics. The mayor of Beijing, Wang Anshun, championed restrictions on vehicles in the city, and state media outlets lauded projects to replace coal-fired heating systems in urban areas with systems that use natural gas and generate far less particulate pollution.
The Berkeley Earth paper showed to clear the skies over Beijing, mitigation measures will be needed across a broad stretch of the country southwest of the capital, affecting tens of millions of people.
"It's not enough to clean up the city," said Elizabeth Muller, executive director of the organization. "You're going to also have to clean up the entire industrial region 200 miles away."
Information for this article was contributed by Dan Levin of The New York Times and by Seth Borenstein of The Associated Press.
A Section on 08/15/2015