Re:Air Pollution in Our Homes
by ip26 on Wednesday May 08, 2019 @03:11PM
(#19861914)
Common sources of formaldehyde would be things like furniture, and another less obvious one would be air infiltration through your walls (picking the formaldehyde up from the engineered lumber) due to a depressurized home envelope (e.g. stack effect). When the house is depressurized enough to really draw in through the walls you should notice a puff of air when you crack a door.
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What causes depressurized houses?
Most often the stack effect (warmth in the house causes air to rise & leak out the attic which sucks in replacement air down low- like a chimney), but also potentially overpowered range hoods, bath fans, clothes dryers, open flue gas appliances, wood fireplaces, etc.
Incidentally this is why there are limits on range hood CFM without makeup air (and there are broader recommendations on overall house design from groups like ASHRAE for air quality management). There are also whole-house leak tests in some regulations, e.g. Title 24 in California.
Typically it's around 300CFM before you should consider a mechanical make-up air device (gravity activated or a makeup air fan tied to the hood activating).