Bay Area Meets U.S. Ozone Standard, Is Taken Off Smog List : Environment: Region becomes largest urban center in nation to comply with federal rules on key pollutant.

Federal authorities are declaring the San Francisco Bay Area a Clean Air Act success story, and removing the nine-county region from a smog watch list.

The U.S. Environmental Protection Agency endorsement Monday makes the Bay Area the largest urban center in the country to meet federal ozone standards, local officials said.

“We’re the cleanest metropolitan area in the United States,” said Teresa Lee, spokeswoman for the Bay Area Air Quality Management District.

“It shows that environmental regulations work. People will be healthier. Business will benefit by less loss of productivity due to illness and less time off from workers having to stay home with their children,” she said.

Hazardous ground-level ozone, a key ingredient of smog, forms when sunlight hits the fossil fuel emissions of traffic, factories and homes.

The Bay Area violated ozone standards 65 days in 1969, the year before the first version of the Clean Air Act went into effect.

Under threat of federal sanctions prescribed by the act, the region managed to bring the violation days down to two in 1994. Since none of the 26 monitoring stations averaged more than one violation a year over three years, the EPA declared the region in compliance.

With the declaration, San Francisco joins Miami, Detroit, Cleveland and Seattle on the clean-air list.

Those cities no longer risk federal sanctions, and escape an EPA mandate to reduce ozone levels another 15%.

The federal limit is 12 parts ozone per 100 million. The San Francisco area has yet to meet the tougher state limit of nine parts per 100 million, exceeding that standard 13 times last year.

Lee said the Bay Area air district will maintain strict controls on industrial solvents and continue to require car-pool plans by large employers.

“We’ve made this milestone, but we don’t see any backpedaling of regulations,” she said.