Air pollution kills about seven million people worldwide every year, with more than half of the fatalities due to fumes from indoor stoves, according to a report from the World Health Organization (WHO) published on Tuesday.
The agency said air pollution is the cause of about one in eight deaths and has now become the single biggest environmental health risk.
“Air pollution, and we’re talking about both indoors and outdoors, is now the biggest environmental health problem, and it’s affecting everyone, both developed and developing countries,” said Maria Neira, WHO’s public and environmental health chief.
WHO estimated that there were about 4.3 million deaths in 2012 caused by indoor air pollution, mostly people cooking inside using wood and coal stoves in Asia. WHO said there were about 3.7 million deaths from outdoor air pollution in 2012, of which nearly 90 percent were in developing countries.
But WHO noted that many people are exposed to both indoor and outdoor air pollution. Due to this overlap, mortality attributed to the two sources cannot simply added together, hence WHO said it lowered the total estimate from around 8 million to 7 million deaths in 2012.
The new estimates are more than double previous figures and based mostly on modelling. 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.
The figures are “shocking and worrying,” Neira told reporters. “The risks from air pollution are now far greater than previously thought or understood, particularly for heart disease and strokes.”
One of the main risks of pollution is that tiny particles can get deep into the lungs, causing irritation. Scientists also suspect air pollution may be to blame for inflammation in the heart, leading to chronic problems or a heart attack.
“We all have to breathe, which makes pollution very hard to avoid,” said Frank Kelly, director of the environmental research group at King’s College London, who was not part of the WHO report.
Other experts said more research was needed to identify the deadliest components of pollution in order to target control measures more effectively.
“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.
The hardest-hit regions were what the WHO labels Southeast Asia, which includes India and Indonesia, and the Western Pacific, ranging from China to the Philippines. They accounted for 3.3 million deaths related to indoor pollution and 2.6 million for the outdoor form, for a total of 5.1 million once the overlap is taken into account.
In Africa, the combined death toll was 680,000, while some 400,000 died in the Middle East, 287,000 in low- and middle-income European countries and 131,000 in Latin America.
High-income nations of Europe saw 295,000 deaths, while 96,000 died in North America and 68,000 in rich Pacific countries, including Australia and Japan.
Despite the increasing use of face masks in heavily polluted cities such as Beijing and Tokyo, Kelly said there was little evidence that they work.
“The real problem is that wearing masks sends out the message we can live with polluted air,” he said. “We need to change our way of life entirely to reduce pollution.”
Women more at risk
WHO’s report noted women had higher levels of exposure than men in developing countries.
“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, WHO Assistant Director-General for family, women and children’s health, said in a statement.
According to the WHO, some 2.9 billion people in poor nations live in homes where fires are the main method of cooking and heating, and thus breathe in soot.
“Having an open fire in your kitchen is like burning 400 cigarettes an hour,” said environmental health expert Kirk Smith, of the University of California at Berkeley, noting that indoor pollution is the largest single health risk for women and girls in India, for example.
In addition to the impact on individuals, 500,000 premature deaths a year are thought to be caused by air pollution in China, for example, the economic burden is huge.
A joint report by the World Bank and Chinese authorities released Tuesday showed that pollution-related death and illness cost the country as much as $300 billion a year.
“You can’t buy clean air in a bottle,” said Carlos Dora, the WHO’s public and environmental health coordinator. “The air is a shared resource. In order to breathe clean air, we have to have interventions in the areas that pollute air.”