The good news is that policymakers know what needs to be done: improving access to public transport, electrifying the transport fleet, raising regulations or pricing emissions on power plants and factories, and developing new technology alternatives to polluting industries, such as steel and cement. All of these measures lead to cleaner air (and lower carbon emissions).
© Clear skies over San Francisco/ Justin Sullivan/ Getty Images
All over the world, people are shocked at the clear skies. From Vancouver, you can see mountains around Seattle. In China and India, you can see across the street. Pollution levels haven’t been so low in decades. That includes levels of fine particulate matter smaller than 2.5 microns in diameter, or PM2.5; a human hair is about 50 microns.
PM2.5 was barely regulated until recently; the USA didn’t even have a standard until 1997 and last revised it in 2012, lowering it to an average annual limit of 12 micrograms per cubic metre (12 μg/m3) with a 24 hour standard of 35μg/m3. The EPA says there is little to no risk under 12μg/m3 and that between 12 and 35, “unusually sensitive individuals may experience respiratory symptoms.” But it turns out that’s not true, especially after COVID-19.

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