The Bay Area Air Quality Management District has issued another Spare the Air day for Sunday.
It is the third consecutive day that residents are banned from burning wood or firelogs because the air quality is expected to be unhealthy.
The use of wood-burning devices including fireplaces, wood stoves and inserts, pellet stoves and outdoor fire pits is illegal.
Wood smoke is the largest source of wintertime air pollution in the Bay Area, according to the air district.
When there is no wind to disperse pollutants from smoke, they become trapped close to the ground and can build up to unhealthy levels, making it difficult for people with asthma and other respiratory conditions to breathe.
For more information about the alert, visit www.sparetheair.org.