00:00You've probably seen headlines like wildfire is now 45% contained.
00:05But what does that actually mean?
00:06It doesn't mean that the fire is almost halfway out.
00:09Containment is about control, not whether the fire is still burning.
00:13So imagine the perimeter of an active wildfire.
00:17Crews build control lines around it using fire retardant or dirt.
00:21They clear brush away to expand barriers like roads.
00:24Sometimes they light backfires to create a bare area around the edge of a fire.
00:29In this example, Incident Command had confidence that the fire would not spread beyond the black perimeter.
00:35But the red parts of the perimeter were still out of control.
00:38The containment percentage tells you how much of the fire's perimeter is surrounded by those barriers.
00:44So if a fire is 25% contained, that means firefighters believe 25% of the fire's edge is unlikely
00:50to spread beyond those lines.
00:52But the fire can still be very active inside that area.
00:56And even a fire that's 100% contained can still smolder for days or weeks.
01:00Strong winds, dry conditions, or spot fires can sometimes cause flames to jump containment lines.
01:05That's why containment percentages can occasionally go down.
01:09A fire becomes controlled only after the flames inside those lines are extinguished and hot spots are cooled down.
01:14So next time you hear 50% containment, think of it as progress in building barriers,
01:19not necessarily the fire being halfway gone.
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