As China’s top officials pledge to declare war on smog, a World Health Organization report said 40 percent of the 7 million people killed by air pollution globally in 2012 lived in the region dominated by that country.

The report released today found that air pollution caused more deaths worldwide than AIDS, diabetes and road injuries combined. WHO Director-General Margaret Chan yesterday called China’s situation a regional health issue that harms the nation’s economy.

Chinese Premier Li Keqiang earlier this month said that air pollution is a top priority for the nation’s authorities. A March 19 study by Columbia University and Chongqing Medical University, meanwhile, found that babies whose mothers were exposed to a Chinese coal-fired power plant had poorer learning and memory skills.

Bad Air Days in China

“Few risks have a greater impact on global health today than air pollution,” said Maria Neira, director of the WHO’s department for public health, environmental and social determinants of health. “The evidence signals the need for concerted action to clean up the air we all breathe.”

The findings suggest that air pollution may now be the world’s largest environmental health risk, the Geneva-based organization said in its report. Low- and middle-income countries in the Western Pacific region, including China, had the highest number of deaths per capita, at 172 per 100,000 people, from indoor and outdoor air pollution combined.

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‘Concerted Action’

The WHO doubled its previous estimates for pollution fatalities in today’s report, revising the figures because the deadly effects of air contaminants, which extend beyond respiratory problems to heart attacks, strokes and cancer, are now better understood.

The health organization didn’t study deaths by country or city, spokeswoman Nada Osseiran said by telephone. Pollution in the Western Pacific region, which includes 37 countries and ranges from China to New Zealand, caused about 2.8 million deaths, the WHO said.

Low- and middle-income European countries came second in deaths per capita from ambient air pollution, while South-East Asian countries were second in deaths from household air pollution.

Indoor Smoke

Indoor smoke killed about 4.3 million people and outdoor air pollution killed about 3.7 million worldwide in 2012. There’s some overlap between deaths from indoor and outdoor factors, the agency said. The WHO previously estimated 2 million deaths in 2004 from indoor pollution and 1.3 million in 2008 from outdoor air contamination.

The biggest culprit inside is poor ventilation of indoor heaters and cookers, the agency said.

“Poor women and children pay a heavy price from indoor air pollution since they spend more time at home breathing in smoke and soot from leaky coal and wood cook stoves,” Flavia Bustreo, the WHO’s assistant director-general for family, women and children’s health, said in the statement.

The new estimates show a stronger link between air pollution and cardiovascular disease such as stroke and heart ailments, in addition to the known connection with respiratory disease, according to the report.

Outdoor air pollution can cause lung cancer and increase the risk of bladder cancer, a World Health Organization agency said in October, ranking it as a carcinogen for the first time.

To contact the reporters on this story: Caroline Chen in New York at cchen509@bloomberg.net; Simeon Bennett in Geneva at sbennett9@bloomberg.net

To contact the editors responsible for this story: Reg Gale at rgale5@bloomberg.net; Phil Serafino at pserafino@bloomberg.net Andrew Pollack