Air pollution kills about 7 million people worldwide every year. More than half of those fatalities were due to fumes from indoor stoves, the World Health Organization reported Tuesday.
WHO reports that in 2012 one in eight of total global deaths were the result of air pollution exposure.
The agency says reducing air pollution could save millions of lives.
USA Today reports women and children in developing countries are at higher risk of exposure than men.
WHO data shows there were about 4.3 million deaths in 2012 caused by indoor air pollution, mostly from cooking inside using wood and coal stoves in Asia. There were about 3.7 million deaths from outdoor air pollution in 2012, of which nearly 90% were in developing countries.
The new estimates are more than double previous figures.
The Associated Press reports the increase is partly due to better information about the health effects of pollution and improved detection methods.
Last year, WHO's cancer agency classified air pollution as a carcinogen, linking dirty air to lung and bladder cancer.
Experts say more research is needed to identify what exactly makes pollution so dangerous.
"We don't know if dust from the Sahara is as bad as diesel fuel or burning coal," said Majid Ezzati, chair in global environmental health at Imperial College London.
It's clear from WHO numbers that poor women and children are bearing more of the health burden from indoor air pollution.
"They spend more time at home breathing in smoke and soot from leaky coal and wood cook stoves," Flavia Bustreo, WHO Assistant Director-General for family, women and children's health, said in a statement.
Included in the assessment is a breakdown of deaths attributed to specific diseases, underlining that the vast majority of air pollution deaths are due to cardiovascular diseases as follows:
Outdoor air pollution-caused deaths – breakdown by disease:
- 40% – ischaemic heart disease;
- 40% – stroke;
- 11% – chronic obstructive pulmonary disease (COPD);
- 6% - lung cancer; and
- 3% – acute lower respiratory infections in children.
Indoor air pollution-caused deaths – breakdown by disease:
- 34% - stroke;
- 26% - ischaemic heart disease;
- 22% - COPD;
- 12% - acute lower respiratory infections in children; and
- 6% - lung cancer.