To fight a fire, you need to survive the fire.
Trainers from the Grissom Fire Department in Indiana set things ablaze to show other firefighters how to fight and survive the flames. They gathered at Grissom Air Reserve Base, and showed the ropes to some DoD and non-DoD firefighters on April 23, 2024. Note what they do at the end: They show that their lungs are clear, as only a firefighter does in full gear.
From a U.S. Air Force video by Senior Airman Elise Faurote.