If smoke remains at the top of a door and does not clear when opened, where is the fire likely located?

The phenomenon of smoke remaining at the top of a door when it is opened typically indicates that the fire is located above the door on a higher level, rather than in the same or lower level. In this scenario, if the smoke does not clear upon opening the door, it suggests that the heat and smoke are accumulating, preventing fresh air from entering and mixing with the smoke, thus indicating a potential fire source in an upper level, like the attic.

While the basement may seem like a possible location for a fire, the behavior of smoke accumulated at the top of the door is more consistent with a fire in an attic or upper story, given that smoke rises. The other choices, such as the first floor or outside the building, would not produce the same accumulation pattern at the top of the door if the fire were located there, as smoke would not rise and settle in the same way. Therefore, recognizing the upward movement of smoke leads to a clearer comprehension that the fire's likely origin is in a higher area, making the attic the most plausible location.