Fighting smog with giant outdoor air purifiers

As citizens in Thailand and Vietnam become more aware of the costs of filthy air, their governments are pushed to respond.

It's the time of year in Thailand and Vietnam when rains taper off, temperatures start falling and the air stills. It's a time when plane-loads full of tourists arrive, and locals trek up mountains to get a taste of temperate climes.

Such holiday weather is unfortunately conducive to smog in cities like Bangkok and Hanoi, where pollutants from construction, industry and traffic grey out the skies and thicken the air. Farmers burning agricultural waste add to the noxious mix which is trapped near the ground by a phenomenon called thermal inversion - where warmer air settles atop a layer of cooler air.

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A version of this article appeared in the print edition of The Straits Times on October 25, 2019, with the headline 'Fighting smog with giant outdoor air purifiers'. Print Edition | Subscribe