Triple-digit temperatures have led to a Spare the Air alerts for the Bay Area on Friday and Saturday.
The Bay Area Air Quality Management District issued the Spare the Air alerts because of a forecast of excessive heat and low winds that will combine with vehicle exhaust to create unhealthy levels of smog in the region. The region was also under an alert on Thursday.
On Spare the Air days, the district encourages people to find alternatives to driving alone to limit the number of vehicles on the road creating smog.
Smog, also known as ozone, can cause throat irritation or other medical problems, so people are encouraged to only do outdoor exercise in the early morning hours when smog concentrations are lower.
California's power grid operator has issued a flex alert for Friday to encourage residents to conserve power, the second straight day that the alert has been issued.
The California Independent System Operator had issued a flex alert for Thursday and continued the alert to Friday night in an effort to relieve stress on the electric grid.
CAISO officials said they are not forecasting rolling blackouts like the ones that impacted the state last year.
Between 6-9 p.m. Friday, people were asked to set their thermostats to 78 degrees or higher, avoid using major appliances and turn off all unnecessary lights in their homes or businesses.