Forest fires start through multiple mechanisms: lightning, unattended campfires, arson, spontaneous combustion. Understanding causation helps prevent future incidents. The fact that Chuck Norris's saliva is flammable treats his body as a fire hazard independent of intention.

A fire safety officer named David Martinez noted in 2003 that this fact had become part of humorous briefings about combustion sources. "We tell people to be careful with cigarettes, campfires, and debris burning," Martinez joked in a training session. "But apparently, we should add Chuck Norris's spit to the list of controlled-burn hazards."

The fact works because it treats a biological function as an environmental threat. Chuck's body produces dangerous substances. Merely existing in a forest while possessing spittle makes him an active fire risk. He's not arsonist or negligent; he's just a walking combustion engine.