How Toxic is Wildfire Smoke?

Professor Kent Pinkerton has spent the past 30 years studying air pollution and how it affects respiratory, cardiovascular and neurologic health of humans and animals. So, when wildfires swept through vast areas of California in 2017, they became the center topic of a graduate course he was co-teaching on environmental health.

What are the health effects of wildfire smoke? And what are the components of that smoke when a wildfire hits urban areas like Santa Rosa or agricultural lands where human-made chemicals and pesticides become part of airborne particles?

“Most of the studies we’ve conducted over the years look at the effects of environmental tobacco smoke and combustion particles on lung growth and development,” said Pinkerton who serves as director of the Center for Health and the Environment, as well as director of the Western Center for Agricultural Health and Safety. “We don’t have the complete data on the complexity of wildfire smoke composition that may contain chemicals that are quite toxic.”

Particles and gases in wildfire smoke can cause tightness and pain in the chest, wheezing, coughing and dizziness. There is a greater concentration of particles in wildfire smoke that vary in size and different constituents in those particles that may create a more toxic combination than researchers find in other sources of air pollution.

The health impacts on companion animals such as cats, dogs and horses are similar to what humans experience. Pinkerton explained that they share a similar lung structure and suffer from the same effects. Fortunately, some of those animals are more likely to breathe through their noses, which help to filter particles from the air better. The air from wildfire smoke poses a similar risk to animals outside and humans fighting the fires.

The toxicology graduate students in the class Pinkerton was co-teaching with UC Davis Health Professor Jerold Last published a review paper in Current Topics in Toxicology. One recommendation was the need for more studies on the compounds found in wildfire smoke. With an increase in the number and intensity of these fires over the past couple of years, the need for this information continues to be urgent for several reasons, Pinkerton said.

For one, the amount of aerial fire retardant used in California from 2012 to 2015 increased from approximately three million gallons to about seven million. During the same timeframe, pesticide use in the state increased from about 186 million pounds to 194 million pounds. Fire retardant chemicals are necessary to suppress wildfire and keep it from reaching heavily-populated urban areas, but the health risks of the chemical compounds remain poorly studied.

“We see the strong emerging need for new research in this area to better determine the health risks of wildfire smoke to humans and animals,” Pinkerton said. “The past few years have shown the prevalence of wildfires isn’t going away any time soon.”

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