The only hangover from the energy conservation effort is the insulated floor over a basement that is not vented to the outside. Anyone who has ever handled fiberglass insulation knows that it is not compatible with the human body. In 1994 the federal government labeled fiberglass as a possible carcinogen, but lobbying convinced congress that people would not normally come into contact with it in everyday life. In most houses it is buried behind the sheetrock in the walls or above it in the attic. The basement is different.
Many people use their basements regularly.
Children play there, washers and dryers are sometimes located in the basement. Fiberglass in the floor joists rains dust down as people walk on the floor above, creating a layer of fiberglass dust on the floor waiting to be stirred up when someone walks through it. Any carpenter or technician who has to work in the insulation years after it was installed can tell tales of the mice residing in it and the unhealthy residue they leave behind. Yes, but the temperature difference is probably only 10 or 15 degrees. A quick trip to the attic will show why.