RAJSHAHI, BANGLADESH — Once upon a time, the sweltering summer in Rajshahi was made worse by a familiar factor on the Asian subcontinent. Windows would have to be bolted shut, not because of the wind or monsoon, but because of the smog.

Dust drummed up from dry riverbeds, fields and roads, and choking smog from ranks of brick kilns on the edge of town helped to secure the place a spot in the top tier of the world’s most polluted cities.

Then suddenly Rajshahi, in Bangladesh, hit a turning point so dramatic that it earned a spot in the record books: last year, according to UN data, the town did more than any other worldwide to rid itself of air particles so harmful to human health.

“We didn’t know about this,” admits Ashraful Haque, the city’s chief engineer, who like some of his fellow residents is rather bemused by the achievement.

Rajshahi does not have a large industrial area, and it is too poor to have streets clogged with cars. Instead, Haque believes it was the campaign to clean up the Read the Full Article