The agency is warning residents not to burn wood or manufactured logs in their fireplaces for 24 hours, beginning at 12 a.m. Saturday.
The AQMD says it's because of the amount of contaminants in the air, which is made worse by wood smoke.
The notice affects residents living in the in the greater Los Angeles metropolitan area, Orange County and the Inland Empire.
The AQMD says the no-burn alert does not apply to residents in mountain communities above 3,000 feet in elevation, the Coachella Valley and the High Desert. Low-income households that rely on fireplaces for heating are also exempt.