Not one single country managed to meet the World Health Organization’s (WHO) air quality standard in 2021, a survey of pollution data in 6,475 cities showed on Tuesday, and smog made a comeback in some regions after a dip due to lockdowns.
The WHO recommends that average annual readings of small and hazardous airborne particles known as PM2.5 should be no more than 5 micrograms per cubic meter after changing its guidelines last year, saying that even low concentrations caused significant health risks. At least 93 cities recorded PM2.5 levels that were 10 times higher than what WHO recommended.
“There are a lot of countries that are making big strides in reduction,” IQAir science manager Christi Schroeder said. “China started with some very big numbers and they are continuing to decrease over time. But there are also places in the world where it is getting significantly worse.”
The data showed that India’s overall pollution levels worsened in 2021 and that New Delhi remained the most polluted capital in the world. It was also revealed that 35 of the 50 cities with the worst air quality are in India, the country is ranked as the fifth most polluted country.
“India’s annual average PM2.5 levels reached 58.1 µg/m3 in 2021, ending a three-year trend of improving air quality. India’s annual PM2.5 averages have now returned to pre-quarantine concentrations measured in 2019.”
As in the previous year, Bangladesh was the most polluted country, while Chad ranked second after their date was included for the first time.
China fell to 22nd place in the PM2.5 rankings in 2021, down from 14th place a year earlier with an average reading of 32.6 micrograms over the year, according to IQAir. Hotan in Xinjiang’s northwestern region is China’s worst-performing city, with an average PM2.5 level reading of over 100 micrograms, largely due to sandstorms.
ARTICLE: PAUL MURDOCH
MANAGING EDITOR: CARSON CHOATE
PHOTO CREDITS: GRIST.ORG