Calculating air pollution from wildfires and other events has become more complicated. That doesn’t mean it’s necessarily more accurate.

Air quality in wildfire-stricken Los Angeles improved on Thursday from hazardous peaks hit earlier this month, as tiny soot particles that can penetrate the lungs and brain dropped to moderate levels,

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.

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.

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."

The National Weather Service has issued an air quality alert due to harmful levels of windblown dust and ash as multiple fires continue to burn in the region.