The city got a grade of "F" from the American Lung Association for its unhealthy air.
With such pollution, Southern California has become a leader in innovations to fight it. Now the roof of a house is being used to combat smog.
"It's new to California. We are just trying it now, but it's been used in Europe for a decade," said Steve Ruffner, president of homebuilding company KB Home Southern California.
Manufactured by Boral Roofing Company, the smog-eating concrete tiles have been used in Germany for 10 years but are the first of their kind in the U.S.
"Built into it is a catalyst, so when the smog hits it, it actually turns it into organic matter, then it falls off and into the soil," Ruffner said. "That organic matter is fertilizer."
KB Home is using them in many of their new home developments.
"We're offering it as an option," Ruffner said. "It will range from $600 to $800, depending on the size of their roof. In several communities like our Martha Stewart community in Hampton at the Enclave in Eastvale, we are going to give it to them as part of the cost of the home."
According to Boral Roofing Company, a 2,000-square-foot house with smog-eating tiles can break down the same amount of pollution a car's engine produces during more than 10,000 miles of driving.
Not in the market for a new home but still want the roof? Just ask your roofing contractor for smog-eating tiles.
Installation is just like any standard concrete roofing tile but the cost of the material is about 25 percent more.