I never read Robert Fulghum’s book, All I Ever Needed to Know I Learned in Kindergarten, but I have a clear memory of learning about one thing in the book: Most of the dust floating around our homes is actually made up of skin flakes. Now, I don’t know if that memory is accurate (maybe it wasn’t from Fulghum’s book?), but I have found out that this tantalizing “fact” about dust and skin flakes isn’t true. Household dust, it turns out, isn’t made up largely of skin flakes. (See this article about a 2009 study on household dust.)
That doesn’t really let skin flakes off the hook, though. There’s still enough of them floating around that they can cause a problem if they find their way into your air conditioner.
HVAC technicians deal with dirty coils all the time. See that photo at the top? That’s a really bad one. Almost no air can get through all that gunk. I did a kind of postmortem on that coil a few years ago, but my focus was on the performance of the air conditioner, not indoor air quality.
Just so you know what an air conditioner’s evaporator coil is supposed to look like, here’s a photo of a nice, clean coil. No gunk. No sludge. Just a bit of water that had condensed on the cold metal fins on that summer day in Atlanta. Air can move through the coil.
A clean air conditioner coil with no skin flakes. [Photo credit: Energy Vanguard]Now look again at the photo at the top of this article. When dirt gets pulled into the duct system and can make it all the way to the coil, that’s what can happen over…