Wildfire doesn’t discriminate between trees and human structures – as last year’s series of California amply demonstrated.

But the chemical reactions that happen when fire consumes manmade materials can leave a significantly different – and more dangerous – footprint behind in the ashes. It's one that can continue to cause harm long after the fire is extinguished, even outside the burned area.

Extensive wildfire in an urban area presents a unique opportunity for researchers to study its effects, and UC Davis scientists are taking full advantage of it.

“By incinerating all kinds of materials – insulation, electronics, furniture, cleaning products, pesticides – at very high temperatures, (wildfires) could have created unknown or previously unrecognized health hazards in the smoke and ash,” said Andy Fell in an article on the UC Davis website.

UCD researchers are now looking at the chemicals left behind in the ashes as well as other impacts, including the self-reported effects on residents in areas affected by wildfire. Gabrielle Black, a PHD candidate in the Young Lab, has collected ash samples for analysis from different sites burned in October’s Tubbs Fire.

Black, a Sonoma native, hopes to gain a better understanding of what substances were left behind after the wildfire, how they might affect residents, and how to protect them from any ill effects. Even as residents sift through the ash of their incinerated homes, stirring it up and sending it airborne, Black and other researchers work to learn about the peculiar nature of these urban fires.

“Hopefully (urban wildfire) never happens again, but if it does, we can use (the research) to formulate plans for cleanup efforts in the future,” Black said in a telephone interview.

Even wildfires fueled mainly by biomass (trees and plant material) can have adverse health effects, including aggravating breathing disorders and affecting drinking water supplies (ash washed into waterways by rain or snowmelt can interact with chemicals used in water treatment to create harmful substances). A fire fueled by a wide variety of manmade products containing various chemicals has the potential for even more harmful effects.

UCD researchers are even looking at the effect of the smoke on garden plants and trees, and whether it could result in toxicity in the fruit later produced.

“This was a very unique type of fire, an urban wildfire,” said researcher Keith Bein. “We know what wildfire smoke is composed of, but we have no idea what will be in this – we expect it to be very different.”