“Why does the wildfire smoke sometimes smell like burning plastic?”

When trees, branches and leaves — also known as biomass — are burned in wildfires, they emit gases called volatile organic compounds. And when these compounds are first emitted, some react quickly and create that recognizable smoke smell typically associated with a campfire.

These longer-surviving compounds, such as benzene and formaldehyde, are “certainly a health concern,” said Dr. Michael Jerrett, a professor of environmental health sciences at the UCLA Fielding School of Public Health. Both benzene and formaldehyde are Group 1 carcinogens, which means a panel of experts at the W.H.O. has found sufficient evidence that these compounds cause cancer. This could indicate the persistent wildfire smoke could potentially get more toxic as time goes on, Dr. Jerrett said, adding that there is limited research on the topic.

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

Read the full New York Times article here.