Recently, I travelled by an ATR 72-500 aircraft. While I was waiting for takeoff, what seemed to be dry ice special effects “smoke” started pouring from the vents. Not being a very frequent flier, I was, naturally, quite frightened. But I seemed to be the only person bothered, as all the others went on unconcernedly with whatever they were doing.
This went on in fits and starts throughout the flight, even after takeoff. What was happening?
If not, was probably condensation from the air conditioning system. Under certain conditions this has happened in several larger aircraft I have flown in and it once even happened in a car once.
You mean the air conditioning vents? It was probably just water vapor. When warm, moist air is cooled it is less able to hold water. It is supposed to condense in the air conditioning unit to be carried away. Some of it apparently condensed in the air and came out the vents as steam (or fog or whatever).
This occurred on one charter flight that I was on to the Caribbean. The only harm was that some of the vapor would condense on the vents and droplets contaminated with rust would fall staining people’s clothes. The flight attendants handed out vouchers for dry cleaning for those people who got “rained on”.