A survey of air pollution data in 6,475 cities shows that not a single country met the World Health Organisation’s air quality standards in 2021. According to a Reuters report, smog even returned to pre-pandemic levels in some regions, after a brief respite during Covid-19. The data was collated by Swiss firm, IQAir, a pollution technology company that monitors air quality. The WHO recommendation is that average annual PM2.5 readings should not exceed 5 micrograms per cubic metre. PM2.5 refers to particulate matter found in the air, such as dust, soot, dirt, liquid droplets, and smoke. The WHO guidelines changed […]
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