But poor air quality has lingered, worsened by winds carrying soil and sand from the Gobi Desert over northern China, including Beijing. India, too, has been enveloped by thick canopies of smog ...

Bangladesh's air consistently ranks among the most polluted on Earth. Brick kilns contribute anywhere from 10 to 40% of the tiny particles that make up that pollution.

Poor air quality isn't always obvious, but it's a serious health issue affecting both our indoor and outdoor environments.