Air quality officials have issued another burn ban for Saturday. It affects Sonoma County south of about Healdsburg.

The Spare the Air Alert, issued by the Bay Area Air Quality Management District, is the 28th of the season. It prohibits people from burning wood, manufactured fire logs or other solid fuel unless it is their only source of heat.

Although some breezy weather has recently kept air pollution from building up, the weather now seems to be returning to what has become a pattern this winter of stagnant air that traps harmful pollution. Specifically, a high-pressure system has strengthened over the region, trapping fine particulate pollution in an unhealthy haze close to the ground, said Jack Broadbent, executive officer of the Air District.

"It's crucial that Bay Area residents not burn wood on Saturday to help protect public health in the Bay Area," he said in a written statement

If someone is found violating the ban, they will be given the option of taking a wood smoke awareness class or paying a $100 ticket. Second violations will result in a $500 ticket.