Air quality is expected to be unhealthy Thursday, so the Bay Area Air Quality Management District has declared a Spare the Air alert for smog. It is the eighth such alert the district has issued, Ralph Borrmann, district spokesman, said.

“High temperatures and low winds, paired with motor vehicle exhaust and potential wildfire smoke from the Happy Camp fire in northwestern California, are expected to cause unhealthy ozone pollution in the Bay Area,” Borrmann said.

“When a Spare the Air alert is issued, outdoor exercise should be done only in the early morning hours when ozone concentrations are lower.”

He said the most effective way for residents to reduce smog is to drive less, pointing to recent census data that shows more than 37 percent of Bay Area employees commute alone to work each day.

To improve air quality, residents are encouraged to walk, bike, carpool or take transit instead of driving alone, not just on Spare the Air days, but every day, Borrmann said.

Those interested can visit the webpage www.stacommutetips.org for commute programs and incentives available where they live and work, he said.

Employees also can check with their employer to see what kind of commute benefit options are offered at their workplace, he said.

The Air District’s own survey showed that employees are more likely to adopt alternatives to driving alone if their employers inform them of such alternatives.

To encourage employers to do so, the Air District now requires companies with 50 or more full-time employees in the district’s geographic area to register by Sept. 30 for the Commuter Benefits Program on the www.511.org website, and to provide simple commuter options for their employees, Borrmann said.

The companies must offer their employees one of the four options in order to comply with Air District Regulation 14 Rule 1, he said.

The first option is to let employees exclude their transit or van pool costs from taxable income until $130 a month, the maximum amount allowed by federal law, is reached.

The second option is for employers to provide a transit subsidy or pass or van pool subsidy of up to $75 a month.

The third option is for employers to provide a free or low-cost bus, shuttle or van pool service.

The fourth is for the company to come up with a benefit that is as effective as the other three in reducing single-occupant vehicles.

Employers can register through the website commuterbenefits.511.org/#options.

Borrmann said Spare the Air alerts are issued when ozone pollution is forecast to reach unhealthy levels.

“Ozone, or smog, can cause throat irritation, congestion, chest pain, trigger asthma, inflame the lining of the lungs and worsen bronchitis and emphysema,” he said.

“Long-term exposure to ozone can reduce lung function.”

Ozone pollution is particularly harmful for young children, older people and those with respiratory and heart conditions, he said.

“Reducing pollution from our daily commute is one of the best ways for the Bay Area to guard against unhealthy air,” said Jack Broadbent, executive officer of the Air District.

“Wildfire smoke may exacerbate already high levels of smog and cause unhealthy air quality.”