At home it matters too. I recover faster from chest colds when I remember to keep the HEPA filter running. (instead of a simple speed knob, it boots up to a multilingual color display that I can't even dim, and of course the filter defaults to "off")

Here is a common air quality problem. Anybody have ideas?

My house is in a hot and humid area, so I run the air conditioning most of the year. The duct work appears to be made of bare fiberglass pressed into sheets, with foil on the outside. This is cheap, quiet, and thermally insulating. It does however have a soft highly porous surface that collects black mold.

It doesn't appear possible to do anything about the mold. Thanks to the soft porous surface, scrubbing would tear up the ducts and be ineffective.

Ideally the ducts would have a polished bare silver surface, sturdy enough to scrub. Well, nobody has that, it would be expensive, and I'd have to rip out the drywall of nearly every room in order to install something like that.

What do I do?