Rides on 21 Bay Area transit agencies, including Caltrain and the Santa Clara Valley Transportation Authority, were free before 9 a.m. on July 26 to encourage commuters to help reduce ozone layer air pollution. The Bay Area Air Quality Management District declared pollution to be at unhealthy levels that day.

The "Free Morning Commute" promotion will be in effect through Oct. 14 when the district issues a "spare the air" alert. Sunnyvale City Councilwoman Julia Miller, who serves on the district's board, says the goal of the promotion is to encourage Bay Area residents to explore their commute options, particularly on days when air quality is poor.

"Carpool or ride a bike," Miller suggests. "Plan your errands if you must go out, or wait until the following day."

Transit agencies participating in the morning commute promotion agreed to measure their ridership on "Spare the Air" days. Last Tuesday Caltrain attracted 5 percent more commuters than usual. "We're very pleased that people got out of their cars," district spokeswoman Terry Lee says. "We hope people who try public transit will stick with it."

Ridership on VTA buses and light rail trains, however, didn't increase. A VTA spokesman said free "Spare the Air" ridership should increase as riders become more aware of this option.

The promotion is an outgrowth of last year's pilot program, when BART offered free morning commutes. This year the district and the Metropolitan Transportation Commission received $3.9 million in federal funds to expand the program.

The district issued just four "Spare the Air" alerts in 2004, down from 10 the previous year, and Lee says only two of these alerts were in effect on weekdays.

The district established the "Spare the Air" program in 1991 to educate the public about summer air pollution in the Bay Area and to promote individual behavior changes that improve air quality. A "Spare the Air" Day is any day between June and mid-October when ozone levels are predicted to exceed the health standards set by the U.S. Environmental Protection Agency.

To help encourage future commuters to adopt "Spare the Air" behaviors, the district created Smogzilla, a Barney-like character that's dispatched to local schools to teach children about air quality. Smogzilla descended on St. Cyprian School in Sunnyvale last spring, and Miller says he's due to put in more local appearances.

"Part of our plan to change commuters' behavior is to teach kids to go home and teach their parents" about air quality, Miller adds.

For more information about the "Free Morning Commute" program, visit www.511.org. To register for "Spare the Air" alerts, visit www.sparetheair.org.