We picked up a small camper for the old F250. Two weeks ago went up to moon lake, that night got a bit cold in the camper so I tried to light a lighter burn the stove for a couple minutes. Lighter would not light, tried a second lighter same thing, got some matches would not light. No air, not enough to even start a match only the sulfer would burn. Did not know a small camper could be so air tight. Still alive and well.