Dr's Casebook: Let the sun into your rooms to reduce risk of infections

Dust can harbour bacteria that can cause respiratory and other infections. Photo: AdobeStockDust can harbour bacteria that can cause respiratory and other infections. Photo: AdobeStock
Dust can harbour bacteria that can cause respiratory and other infections. Photo: AdobeStock
​Our weather seems quite chaotic at times. Sunny spells amid prolonged episodes of rain. The sun is important to our health and research has shown that letting the sun into buildings and rooms actually reduces infections.

Dr Keith Souter writes: It does this because of its effect on dust in rooms. You shouldn’t think of dust as being inert and of no significance. The fact is that dust can harbour bacteria that can cause respiratory and other infections.

Dust balls are those balls of fluff and dust that seem to appear magically under beds, couches and furniture. They are interesting because of the way they form in even the most house-proud of homes. They are made up of hair, carpet fibres, human skin cells, cobwebs and microscopic debris including bacteria. Static electricity is the force that makes them form into fluffy balls, then the loose fibres hold them together.

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Air currents move them about under furniture, like miniature tumbleweeds.

Researchers from the University of Oregon created 11 identical climate controlled miniature rooms that mimicked real buildings. They seeded them with dust collected in ordinary homes. They applied one of three glazing treatments to the windows, so they transmitted either UV, visible daylight or no light at all.

After 90 days they analysed the dust in all the rooms. They found that in dark rooms 12 per cent of bacteria in dust were alive and able to reproduce. In comparison only 6.8 per cent of bacteria exposed to daylight and six per cent exposed to UV light were viable.

We spend most of our lives indoors exposed to dust, so these findings are important. Dust kept in the dark contains bacteria closely related to common respiratory infectious bacteria.

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This may explain why people even pick up infections when they never go out and aren’t exposed to coughs and colds. It may be those dust tumbleweeds that harbour bacteria. When they move about, perhaps from the tiny drafts caused when doors open and close some may be released and inhaled.

It is interesting that sunlight seems to kill off half of the bacteria that are capable of causing infections. Good reason to pull back the curtains and let the sun shine in and get rid of the dust balls, especially the ones that collect under beds.