Los Angeles health officials warned on Monday of unhealthy air caused by smoke from wildfires in most of Southern California.
Jonathan Fielding, Director of Los Angeles County Public Health Department, cautioned residents to avoid unnecessary outdoor activities in areas where they can see or smell smoke.
Sensitive individuals -- those with respiratory or heart disease -- should stay indoors even if they can't see or smell smoke, he said.
"It is difficult to tell where ash or soot from a wildfire would go or how winds would affect the level of dust particles in the air, so we ask everyone to be aware of their immediate environment and how it might affect their health," Fielding said.
Officials advised schools that are in session in smoke-impacted areas to keep students indoors for physical education and after- school sports until the smoke clears.
All schools in the Los Angeles Unified School District would be on a regular schedule on Monday, but all outdoor activities would be cancelled, said District Spokeswoman Gayle Pollard-Terry.
Several wildfires had been raging over the weekend across Southern California, destroying hundreds of homes and forcing thousands of residents to flee.
Fire-fighters said that as winds were calm Monday, they were making headway in containing two raging wildfires.