Formaldehyde is one of the compounds that are present in smoke from fires.

Source: Whalen, Mike, Brad, Washa, Haddow, Dennis, Acheson, Ann, Ottmar, Roger, Vickory, Chuck, Seamon, Paula, Sanders, Craig, Blake, Tim, and Forrest Davis, Zoila. 2003. Smoke Management Techniques RX-410. A publication of the National Wildfire Coordinating Group.