Temperatures are expected to reach 100 degrees in many parts of the Bay Area on Friday, according to the National Weather Service.
As a result, the Bay Area Air Quality Management District has issued another Spare the Air alert for the region for Friday.
The alert was issued because hot temperatures are forecast and high levels of ozone pollution are expected at the ground level.
Thursday is also a Spare the Air day.
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.
The hot weather also heightens fire danger, particularly in areas with dry grass or brush, Cal Fire spokesman Dan Berlant said. Campers and
hikers should be especially careful when using fire in brushy areas, he said.
Those sticking close to home are also advised to be vigilant.
"One of the common causes of fires at home is equipment use, such as lawnmowers or weed-eaters," Berlant said. "On a hot day, especially when it's windy, it's easy for a mower blade to strike a rock and spark a fire on
Temperatures should begin to cool off on Sunday, Monday and Tuesday, according to Meteorologist Steve Anderson.