A Spare the Air alert has been issued for Friday in Pleasanton because of expected unhealthy pollution levels.
The Bay Area Air Quality Management District issued the alert, its seventh of the summer season, because of a combination of high temperatures, low winds and vehicle exhaust that is expected to cause unhealthy ozone pollution.
"Motor vehicles are the number one source of smog in the Bay Area, so going where you need to go without your car can make a big difference in
air quality all summer long," air district executive officer Jack Broadbent said.
The most recent Spare the Air alert was issued for last Friday because of similar hot weather and low winds, according to the air district.