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.

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 research organization based in Berkeley, Calif., that uses statistical techniques to analyze environmental issues. The 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 three-eighths of the Chinese population breathe air that would be rated “unhealthy” by United States standards. The most dangerous of the pollutants studied were fine airborne particles less than 2.5 microns in diameter, which 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.