Class A Commercial Driver License (CDL) HAZMAT Endorsement Practice Exam

Keep ignition sources away from hazmat cargo. When a vehicle carries explosives, oxidizers, or flammables, smoking nearby can ignite flammable vapors or dust even if a leak isn’t visible. The standard safety margin is to keep at least 25 feet between anyone smoking and the vehicle. This distance reduces the chance that smoke, embers, or vapors could reach a source of ignition.

Smaller distances wouldn’t provide enough clearance to prevent ignition risk, while larger distances are more conservative or used in different safety rules, but 25 feet is the amount tested for this scenario.