Latest satellite images have shown out-of-control wildfires that have been  polluting Southern California skies with acrid smoke and falling ash for a third straight day,as public health officials urge the elderly and people with breathing problems to stay indoors.

The images showed thick smoke from more than a dozen wind-driven blazes blanketing a wide swath from Malibu to the Mexican border. State air regulators warned that the region's air quality has deteriorated since Sunday with concentrations of soot particles at unhealthy levels.

The South Coast Air Quality Management District has received dozens of calls from concerned parents wanting to know how to protect their children from the pollution.

The unhealthy air was expected to linger as long as the wildfires burn. It can take up to two days for the smoke to clear once the blazes are put out, experts say. The last time the air was this polluted was in 2003 when massive wildfires raged around the state.

Workers at the Del Mar Fairgrounds near San Diego put out a call Tuesday for more face masks for evacuees.

At the Henry Mayo Newhall Memorial Hospital in the Santa Clarita Valley north of Los Angeles where fires were burning, 22 people arrived at the emergency room complaining of respiratory problems, most likely from the smoke. At least two stayed overnight, hospital spokeswoman Bhavna Mistry said.

Sixteen patients, including four firefighters, were treated for burns at the University of California San Diego Medical Center. Of those, five also suffered from smoke inhalation.