The Bay Area Air Quality Management District has issued another Spare the Air alert for the region for Friday, Aug. 10.
The alert was issued because hot temperatures are forecast and high levels of ozone pollution are expected at the ground level.
Residents are advised to walk, bike, carpool or take public transit to work, and to avoid pollution-creating activities such as using gas-powered lawnmowers or aerosol products.
The air district warns that high ozone levels are particularly hazardous for children, seniors and anyone with respiratory problems or a heart condition.
District officials urge residents to avoid vigorous outdoor exercise, except early in the morning when pollution levels are lower.