Why does wildfire smoke sometimes smell like burning plastic?

As smoke from wildfires continued to cloak parts of the United States and Canada, some residents reported smelling a burning campfire. But other residents said they smelled burning plastic and chemicals outside. What caused the strange smell?

Kang Sun, an assistant professor at the University at Buffalo who studies the chemistry and physics of Earth’s atmosphere, said that when trees, branches and leaves — known as biomass — are burned in wildfires, they emit gases that contain volatile organic compounds. substances are mentioned.

And when these compounds are first emitted, some react quickly and create that recognizable smoke smell typical of a campfire.

But some connections are stable enough to travel thousands of miles downwind to Michigan and upstate New York from the fires in Canada, said Dr. Sun. Other molecular compounds are also formed as by-products of previous chemical reactions.

Some molecules can cause the chemical, plastic smell that many people have reported recently. Opening a window himself in Buffalo on Wednesday, Dr. Sun, he also smelled the acrid, burning smell of plastics and plastics, rather than the smell of a campfire.

These longer-surviving compounds, such as benzene and formaldehyde, are “certainly a health concern,” said Michael Jerrett, a professor of environmental health sciences at the UCLA Fielding School of Public Health.

Both benzene And formaldehyde are group 1 carcinogens, meaning that a WHO expert panel has found sufficient evidence that these compounds cause cancer. This could indicate that the lingering wildfire smoke could potentially become more toxic over time, said Dr. Jerrett, adding that there is limited research on the subject.

In the short term, the best thing people can do to stay safe is to stay indoors as much as possible, Dr Jerrett said. The compounds may not pose a health hazard unless the smoke persists for a long period of time, he said.