The World Health Organization has released stringent air pollution guidelines in response to the latest information on the damaging effect on health, but experts say none of the world’s 100 biggest cities would meet the updated rules.
In one of the most significant revisions since the standards were established in 1987, the UN agency cut in half the level of fine particulate matter, or PM2.5, deemed acceptable for an individual’s annual average exposure.
Fine particulate matter can travel through the lungs directly into the bloodstream, and is linked to heart disease and stroke.
The WHO rules, although not legally binding, serve as the basis for health guidance in dozens of countries.
Tedros Adhanom Ghebreyesus WHO director-general, said the guidelines had been updated for the first time in 16 years based on research showing that air pollution has a big impact on health, even at lower concentrations.
For nitrogen dioxide, a pollutant emitted by diesel vehicles, the guidance for annual exposure was lowered to 10 micrograms per cubic metre, from 40.
Cities such as London that have worked hard to reduce their nitrogen dioxide levels by reducing the presence of diesel vehicles will now have an even tougher threshold to achieve.
For countries where diesel vehicles are still commonplace, particularly in the developing world, meeting the new standard would require radical changes to transportation.
“Air pollution is a threat to health in all countries, but it hits people in low- and middle-income countries the hardest,” said Ghebreyesus. About 7m premature deaths each year are related to air pollution, according to the WHO.
Under the new standards, not a single one of the 100 largest cities in the world meets the guidance for the level of fine particulate matter, according to city-level data from IQAir analysed by Greenpeace.
Using air quality data for PM2.5 in 2020, New Delhi was 16 times higher than the new limit, Beijing was seven times higher, London was twice as high with New York 1.4 times above the safe guideline.
Under the previous guidelines, about 79 out of the 100 most populous cities failed to meet the recommendations. Under the updated rules, 92 out of the 100 cities miss the targets, according to Greenpeace analysis. The other eight cities have no data available.
About 80 per cent of deaths related to fine particulate matter could be avoided if pollution levels were cut to be in line with the new guidance, the WHO said.
Air pollution experts said the guidelines would be extremely difficult to meet, even in wealthy countries such as the UK, because of background sources of air pollution.
“The new guidelines will not be achievable for decades, if at all,” said Roy Harrison, a professor of environmental health at the University of Birmingham, and a member of the WHO panel for the 2005 guidelines. He pointed to exhaust sources such as car tyre brakes that are difficult to eliminate.
Nevertheless Harrison said that he welcomed the guidelines. “The WHO has followed the science which now shows adverse effects of nitrogen dioxide and fine particle [PM2.5] exposure at well below the 2005 guideline levels,” he said.
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