The Bay Area Air Quality Management District has declared Friday a "Spare the Air" day, marking the third consecutive day the health advisory has been issued and the 11th time this season.
Spare the Air advisories are issued when there is a forecast of unhealthy air quality in the region.
"This third consecutive Spare the Air day reinforces our need to make clean air choices every day,'' air district executive officer Jack
Broadbent said in a prepared statement.
"Reducing the amount of single-passenger vehicles on the roads every day is the most important action we can take to reduce air pollution in the Bay Area,'' he said.
Officials are again warning residents that vigorous outdoor exercise should only be done in the early morning hours when pollution levels are lower.
They are also reminding residents that ozone pollution is especially harmful to young children, seniors and people with respiratory and
Bay Area transit agencies will not offer free transportation Friday.