Is house dust mostly dead skin?

When you tackle the baseboards with a dust cloth, is it your own dead skin that is being cleaned?

There is a myth that house dust is mostly human skin. The makeup of house dust is made up of skin cells, but there are other components on top of the ceiling fan blades. According to the Canadian Centre for Architecture, these include paint, fibers, mold, hair, building materials, pollen,bacteria, viruses, insect body parts, flakes of skin, ash, soot, minerals and bits of soil.

The Canadian Dust Study collected dust samples from 1,025 Canadian homes in order to quantify the prevalence of lead. The proportions of each component are different from household to household. A newly built home might have a lot of construction debris floating around. A home in the middle of nowhere is likely to have a lower level of pollutants from car exhaust than a house near a busy road. In the Canadian Dust Study, older homes had higher levels of lead in their house dust, no surprise given that lead paint and leaded gasoline were phased out in the late 1970s.

Most houses do not have 70% or 80% of house dust being human skin. According to a study done in the U.S. Midwest, 40% of the dust came from outside and 40% came from inside. It included everything from organic fibers to building materials.

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A lot of skin cells are dropped by people. According to the American Chemical Society, the average adult loses 500 million skin cells each day. In fact, according to Mary Roach's book, "Packing for Mars", part of the preparations to send humans to the moon involved having test subjects avoid. The commander of the Gemini 7 mission, Frank Borman, did report a build up of skin cells on his head, but his crewmate, Jim Lovell, told Roach that there were no problems with floating zero-G skin cells in the craft.

Not all dead skin is washed off onto the floor of your home, but many bits end up in the shower or bath drain and are washed out in the washing machine.

It may be a good idea to have a small amount of skin in your home. A study done in 2011 found that higher levels of cholesterol and squalene in dust were associated with lower levels of ozone indoors. Ozone can cause lung irritation. Ozone reacts with oils like squalene and cholesterol, though, and the 2011 study found that squalene in dust can reduce indoor ozone by between 2% and 15%.

It was originally published on Live Science.