National Public Radio: The Houston area produces about a quarter of the nation's gasoline, and about a third of the plastics that are in our cars, cupboards and just about everywhere else. So it is no surprise that this heavily industrial area has a problem with air pollution. But in the past decade, Houston's air has improved dramatically.
How that happened is a tale of good science, new technology and a Texas law that prompted companies along the Houston Ship Channel to disclose their emissions.
This image, from...