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Millions of deaths could be avoided if the world adopts tough new air pollution limits set out today by the World Health Organization (WHO).

The guidelines call for much lower daily and annual levels of exposure to six pollutants from cars, power stations and other sources, in the first major overhaul of the recommendations in 16 years. The stricter ceilings are due to an increase in research on the health impacts from even low levels of pollution.

“We have even stronger evidence than before on the effect of air pollution on health. Before our evidence was huge, now it’s even stronger,” says Maria Neira at the WHO.

Stephen Holgate at the University of Southampton, UK, says population-based studies have shown “there are no safe levels of air pollution”.

The WHO’s air quality guidance isn’t legally binding but influences governments, and clean air campaigners have increasingly been calling for stricter measures.

Under the new advice, annual limits on people’s exposure to tiny particulate matter known as PM2.5, which mostly comes from burning fossil fuels in cars and industry, are halved. Annual exposure to nitrogen dioxide, a toxic gas from diesel vehicles, is cut by 75 per cent.

Air pollution is currently the world’s greatest environmental threat to health, resulting in 7 million premature deaths a year, according to the WHO, although some estimates are even higher.
The WHO calculates that if the world met the new PM2.5 limits, ignoring other measures, it would cut deaths due to PM2.5 by about 80 per cent, or 3.3 million people a year. “How can you refuse to reduce by 80 per cent?” says Neira.

Air quality experts say the new limits are in line with the science on the health impact of exposure to dirty air. “These are really quite significant developments. It’s very dramatic. But it does reflect the current state of the literature,” says Jonathan Grigg at Queen Mary University of London.

“Harms to health occur throughout the entire life course, but pregnancy and childhood are especially vulnerable periods, with mounting evidence for effects on long-term growth and cognitive ability,” says Frank Kelly at Imperial College London. “We need to view air pollution much more seriously, as it is a major public health problem.” Meeting the new guidelines is feasible but will be a challenge, especially in many UK cities, he adds.

Grigg says the UK government should consider immediately adopting the new guidelines, using the Environment Bill moving through parliament. “We could lead the world,” he says. A spokesperson for the UK Department for Environment, Food & Rural Affairs says: “We will consider the updated WHO guidelines on PM2.5 to inform the development of air quality targets, but we must not underestimate the challenges these would bring, particularly in large cities and for people’s daily lives.”

Globally, 91 per cent of the world’s population lives in areas that exceed the old limits. Asia has a particularly high death toll linked to dirty air, with people in cities across China and India breathing some of the highest levels of particulate pollution.

Because of the difficulty of making such big air pollution cuts, the WHO has also published easier interim targets. Neira says countries should remember that cleaning up their air will not only save lives, but protect against future respiratory diseases and help meet climate goals.

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