Wildfire ash carries many carcinogens that could cause short- and long-term health problems, including asthma attacks and difficulty breathing.

The fresh air came after days of acrid smoke from wildfires, but officials warned that conditions could rapidly worsen again.

A dust and ash advisory has been issued for L.A. County until 7 p.m. Wednesday "due to harmful particle pollution levels from windblown dust and ash."

Los Angeles is now a week removed from the day that multiple devastating wildfires erupted to torch tens of thousands of acres. But still, the question remains if people should wear masks to limit their exposure to toxins in the air.

Ash from the recent LA County fires and burn scars formed by other wildfires in the fall can be dispersed by strong winds. See an air quality map.

Massive fires continue burning after igniting in the foothills of Pacific Palisades, and Altadena, forcing thousands to evacuate amid a life-threatening and destructive windstorm slamming Southern California.