There Are Over 9,000 Microbes In Your Household Dust

Kate Solomon
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Dust. It’s everywhere, yet we still don’t have comprehensive information about what it actually is.

But a new study fresh out of the US has found that what’s in our dust largely depends on where we are in the world and who lives in our house.

Over 1,200 households from around US sent in dust samples from the top ledges of doorways in their homes for the researchers to analyse.

In general, they found that household dust contains an average of 9,000 different microbes including over 2,000 types of fungi and 7,000 kinds of bacteria - but exactly what kinds of bacteria and fungi depend on where you live.

“Most of the fungi we are seeing in the home appears to be coming from outside the home,” Dr Noah Fierer, associate professor of ecology and evolutionary biology, who carried out the study, told the BBC.

“They enter the home on our clothing, or through open windows or through doors. Therefore the best predictor of what types of fungi are in your home is where your home is located.”

One thing that affected the various bacteria found in dust was gender. The results were different for female- and male-only households because men and women’s bodies carry different bacteria.

But the thing that has the biggest impact is your pet: “Bringing a dog or cat into your home really has a significant effect on the bacteria you find in your home.

"It was surprising to us that it was such a strong influence - stronger than any other factor, stronger than where your home was located or the design of your home, for example.”

As for the 7,000 types of bacteria, some (including Staphylococcus and Streptococcus) are likely from human skin. But others, such as Bacteroides and Faecalibacterium, are linked to faeces which is something to think about next time you do the dusting.

It sounds gross, but the scientists were keen to stress that you don’t need to worry about the microbes in your home.

“Most of these are completely harmless,“ Dr Fieri said. “It is just a fact of life that we are surrounded by these microbes.”