The life expectancy of a child born today could be reduced by an average of 20 months due to health damage caused by air pollution, researchers say.
The annual State of Global Air report said life expectancy for children can fall by more than 30 months in South Asian countries where air pollution levels are highest.
Published by US-based nonprofit research group Health Effects Institute, the report said air pollution is the fifth leading cause of death, killing more people each year than road accidents and malaria, the report said.
"A child's health is critical to the future of every society, and this newest evidence suggests a much shorter life for anyone born into highly polluted air," Health Effects Institute president Dan Greenbaum said.
"In much of the world, just breathing in an average city is the health equivalent to being a heavy smoker," he said.
The analysis found long-term exposure to indoor and outdoor pollution contributed to almost five million deaths in 2017, with fatalities resulting from stroke, heart attack, diabetes, lung cancer and chronic lung disease.
For household air pollution, the research determined the main causes included the burning of smoky fuels such as wood or coal for cooking.
Among the primary sources of outdoor pollution were vehicle and industrial emissions, as well as coal-burning power plants.
About half of the total deaths in 2017 occurred in China and India together, it said. More than 1.2 million early deaths were caused by air pollution in each country that year.
And while China had made progress in reducing air pollution, the report found the biggest increases in air pollution since 2010 were in Pakistan, Bangladesh and India.
Its conclusions illuminate what "we're seeing more and more of each year" in terms of health impacts stemming from air pollution, said Alastair Harper, head of advocacy at Unicef UK, the British arm of the UN children's agency.
Some of the risks for children from exposure to air pollution are potential damage to brain development, limited lung capacity and the onset of problems like asthma, he said.
"Children are especially vulnerable because of the fact that they are developing, and breathe more often than adults," Harper said.
"We have no excuse to stand by and do nothing. It's incumbent on governments around the world to do something about this."
The report was co-produced by the Institute for Health Metrics and Evaluation at the University of Washington.
