One of the frustrating things about house cleaning is that no matter how clean you try to keep things, household dust still accumulates. That grey dust, it turns out, is largely human skin. The tiny flakes of skin that we lose on a daily basis create over seventy percent of the dust in our home.

Dry skin is a translucent grey colour. Of course humans come in different colours, but the pigments which colour our skin are found beneath the layer that we shed. Blood vessels, too, are much deeper down, and are not lost as skin sheds. Therefore, there is neither blood nor pigment to colour the grey skin dust.

The epidermis, or outer layer of skin, sheds skin cells and replaces them with healthy new cells. The epidermis is completely replaced once a month. It’s estimated that everyone sheds about half a kilogram of skin a year, as our skin cells are continually replaced. Unfortunately, we don’t replace the lower layer of skin called the dermis where scars and stretch marks occur. Since this layer doesn’t shed, the scars stay with us.

Beyond the seventy percent of skin dust, the remaining thirty percent of house dust comes in different colours because it’s mostly wind blown soil, varying according to our geographic location.

So next time you dust, remember that grey powder is largely made up of members of your family or friends who’ve left it behind.