MUMBAI • About 300 million children in the world breathe highly toxic air, Unicef said in a report released yesterday that used satellite imagery to illustrate the magnitude of the problem.
The vast majority of these children, about 220 million, live in South Asia, in places where air pollution is at least six times the level that the World Health Organisation (WHO) considers safe, Unicef said.
The United Nations children's agency said these youngsters faced serious health risks as a result.
"Children are uniquely vulnerable because their lungs are still developing," said Mr Nicholas Rees, the author of the report. "Early exposure to toxic air has lifelong consequences for them," he said.
Among the most dangerous pollutants are air particles known as PM2.5, which are a small fraction of the width of a human hair strand. They can come from fossil fuel combustion and industry, and include natural sources such as dust.
The ultra-fine particles enter the bloodstream through the lungs, worsening cardiac disease and increasing the risk of stroke and heart failure, in addition to causing severe respiratory problems such as asthma and pneumonia.
Early studies also suggest a possible link between pollution and children's cognitive function, the Unicef report noted.
In addition, it cited numerous studies connecting chronic exposure to high pollution with an increased risk of miscarriage and early labour in pregnant women, and low birth weight.
Globally, about seven million deaths each year are linked to air pollution, 600,000 of them children younger than five, the Unicef report said, citing WHO studies done in 2012 and last year.
About two billion children globally, constituting the vast majority, live in places where the level of air pollution is considered unhealthy by WHO, the report said.