Spare the Air days are declared when the Bay Area is expected to have poor air quality in an effort to alert the public of health hazards and reduce the number of cars on the road.
The Bay Area Air Quality Management District has already issued three Spare the Air days - one last Thursday and two in May -- for this year's summer season, but free transit was not provided on those days.
The air district is providing free transit on a planned Spare the Air Day in order to give residents time to plan their routes and schedules around taking public transportation, air district spokeswoman Kristine Roselius said.
The Spare the Air Day coincides with the third annual National Dump the Pump Day, which attempts to raise awareness about conserving fuel in the environment, according to Roselius.
