Houston has earned the title of smoggiest city in the U.S. this year, a distinction gladly abdicated by Los Angeles. In 1999, Houston has had 44 days when ozone levels exceeded national health standards, one more than the L.A. region, and for the first year in more than five decades, the L.A. area has not had a full-scale smog alert. Most of the credit for this year’s relatively light smog in L.A. goes to weather conditions, but the city has been steadily improving its air quality by enforcing the strictest anti-smog rules in the world, regulating everything from automobiles to hairspray and paint. Still, enviros and the EPA say the city needs to do more.

Grist thanks its sponsors. Become one.