The human component of household dust

Dear Matthew Alice: My roommate claims that some 75 percent of household dust is made up of dander — tiny flakes of dead human skin. I say that household dust is at least 90 percent comprised of cloth fibers rubbed off the carpet, clothes, upholstery, bedding, etc. Help! The vacuum cleaner bag awaits whomever is wrong! — Mike (me), Tony (roommate), Tierrasanta

Unless (roommate) is subhuman, I wouldn’t call it dander. On people it’s just dead skin. Otherwise, (roommate) is probably closer to the truth, though I wouldn’t swear to the percentages. It depends on the makeup of your environment, but a good chunk of what’s m the bag is dead skin, which we shed constantly. Though, pound for pound, the dust mites that feed on the dead skin in the vacuum cleaner bag may be the winners. Yuk.