If a hazardous material incident involves a leaking flammable substance, first responders should immediately remove all which?

• A. ignition sources.
• B. upwind ignition sources.
• C. large combustible tanks.
• D. fire equipment and personnel.

Answer: (A)

The main idea is to prevent ignition by eliminating anything that could spark or heat the flammable vapors. When a flammable substance leaks, it releases vapors that can mix with air and form an ignitable mixture. A small spark, hot surface, open flame, or even static discharge can ignite those vapors, causing a flash fire or explosion. Because ignition can happen quickly, the immediate action is to remove all potential ignition sources from the area of the release. This includes shutting off electrical equipment, stopping flames or smoking, and using grounding and bonding to prevent static sparks, as well as avoiding the use of any non-intrinsically safe tools or devices. By removing ignition sources right away, you cut the most likely path to ignition and buy time to control the leak.

Isolating the area or moving other equipment can be part of the broader response, but those actions don’t replace the need to eliminate sources of ignition in the immediate vicinity. Large tanks or fire personnel aren’t something you simply remove; they’re part of the response to manage the incident. The focus here is on halting the spark-and-flame risk as soon as possible to prevent a ignition of the vapor cloud.