Bay Area sets record with 26th smog alert Saturday

FILE-- Runners and surfers enjoy the warm weather at Ocean Beach in San Francisco on Feb. 2, 2015. More sunny skies and toasty temperatures are in store the rest of this week for the Bay Area. The Bay Area Quality Management District issued its 26th Spare the Air alert of the year on Saturday, Oct. 8, 2016. less FILE-- Runners and surfers enjoy the warm weather at Ocean Beach in San Francisco on Feb. 2, 2015. More sunny skies and toasty temperatures are in store the rest of this week for the Bay Area. The Bay Area ... more Photo: Jessica Christian / The Chronicle / / Photo: Jessica Christian / The Chronicle / / Image 1 of / 4 Caption Close Bay Area sets record with 26th smog alert Saturday 1 / 4 Back to Gallery

As temperatures climbed into the 80s Saturday, the Bay Area broke the record for the number of smog advisory days in a single season.

The Bay Area Quality Management District issued its 26th Spare the Air alert of the year, citing hot temperatures and light offshore winds, combined with “motor vehicle exhaust from traffic,” as the root cause of unhealthy air conditions Saturday.

“With a record-breaking number of Spare the Air Alerts this year, this is a wake-up call that we must reduce the number of cars on Bay Area roads,” Jack Broadbent, the air district’s executive officer, said in a news release. “Increased employment rates and traffic congestion underscore the need to find alternatives to driving alone.”

Spare the Air Alerts are issued by the air district when ozone pollution, or smog, is expected to hit unhealthy levels due to a combination of weather and atmospheric conditions. San Francisco and coastal regions were issued a moderate warning, while parts of the East Bay were expected to be worse, with conditions considered unhealthy for sensitive groups.

Breathing in air with unhealthy levels of ozone pollution can trigger asthma attacks, inflame the lining of people’s lungs, worsen bronchitis and emphysema and cause throat irritation, congestion and chest pain.

The air district warned that ozone pollution may be particularly harmful to young children, seniors and those with respiratory and heart conditions.

To limit exposure to unhealthy ozone levels, the air district advised, “outdoor exercise should be done only in the early morning hours when ozone concentrations are lower.”

Bay Are residents were encouraged to carpool, bike, walk or take public transportation instead of driving alone.

Mercury levels Saturday were expected to rise as much as 10 degrees above average temperatures for this time of year, according to the National Weather Service, which predicted a clear and sunny weekend.

Air quality was expected to improve Sunday, the district said, as onshore winds pick up.

On Monday, temperatures seemed likely to dip back down to seasonal norms — low 70s in the Bay Area. By midweek, a forecaster said, sunny skies may be overtaken by clouds, with rain headed to the region by late in the week.

Marissa Lang is a San Francisco Chronicle staff writer. Email: mlang@sfchronicle.com