A Spare the Air smog alert has been issued for Friday, the second straight day that an unhealthy amount of ozone accumulation is expected in the Bay Area, air quality officials said.
The Bay Area Air Quality Management District issued the alert because of forecasted hot weather and low winds that are expected to combine with motor vehicle exhaust to create high levels of smog.
On a Spare the Air day, commuters are asked to avoid driving alone and instead take public transit, carpool, walk or bike to work to reduce smog levels, according to the air district.
Smog can cause throat irritation, congestion, chest pain, asthma and can worsen bronchitis and emphysema.
The summer Spare the Air season started on April 28 and today's and Friday's alerts are the first and second of the season, air district officials said.