As wildfires rage across Los Angeles, the smoke billowing into the air carries more than the expected risks of particulate matter and carbon emissions.
Urban wildfires, unlike those in remote forests, burn through large areas of neighbourhoods filled with synthetic materials like plastics, rubber, fiberglass and treated asphalt, releasing a cocktail of hazardous chemicals into the air.
“Wildfire smoke when it’s purely burning biomass is bad enough. But when there are large fires in the wild and urban interface, then you get all these kinds of smoke and toxins that are from structural fires,” said John Balmes, a professor emeritus at the University of California, San Francisco, and the University of California, Berkeley.
“It’s much more toxic. The combination of burning biomass and structural fire smoke… like the Palisades fire, that is blocks and blocks of homes, that is particularly toxic smoke,” he added.
As wildfires rage through forests, grasslands and urban areas, they burn a variety of natural and human-made materials, producing a dense, hazardous smoke.
This smoke is a mixture of gases and fine particles, with some of the most dangerous components being particulate matter (PM2.5), carbon monoxide, carbon dioxide, volatile organic compounds (VOCs), and a range of toxic chemicals.
PM2.5 refers to tiny particles that are less than 2.5 micrometers in diameter — far smaller than the width of a human hair. These particles, though invisible to the naked eye, are extremely dangerous. And because of their tiny size, they can easily penetrate deep into the lungs, and even enter the bloodstream, posing serious health risks.
There is no known safe level of exposure to some of these pollutants, meaning that even low levels of wildfire smoke can negatively impact your health, according to Health Canada.