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How keeping the windows clean and curtains open could stop you getting ill

Sunlight kills bacteria that can make people ill, a new study suggests  - The Image Bank
Sunlight kills bacteria that can make people ill, a new study suggests - The Image Bank

It is a simple strategy for staying healthy, but a new study has found that allowing sunlight to stream in through windows could kill bacteria that live in dust.

Researchers at the University of Oregon found that in dark rooms 12 per cent of bacteria on average were alive and able to reproduce.

In comparison only 6.8 per cent of bacteria exposed to daylight and 6.1 per cent of bacteria exposed to UV light were able to replicate.

Lead author Dr Ashkaan Fahimipour said: “Humans spend most of their time indoors, where exposure to dust particles that carry a variety of bacteria, including pathogens that can make us sick, is unavoidable.

“Therefore, it is important to understand how features of the buildings we occupy influence dust ecosystems and how this could affect our health.”

The researchers made eleven identical climate-controlled miniature rooms that mimicked real buildings and seeded them with dust collected in residential homes.

Sunlight may stop bacteria being able to replicate - Credit: HO Reuters 
Sunlight may stop bacteria being able to replicate Credit: HO Reuters

The authors applied one of three glazing treatments to the windows of the rooms, so that they transmitted visible, ultraviolet or no light.

After 90 days, the authors collected dust from each environment and analysed the composition, abundance, and viability of the bacteria present.

Dust kept in the dark contained organisms closely related to species associated with respiratory diseases, which were largely absent in dust exposed to daylight.

The authors also found that a smaller proportion of human skin-derived bacteria and a larger proportion of outdoor air-derived bacteria lived in dust exposed to light that in than in dust not exposed to light.

They believe it may suggest that daylight causes the microbiome of indoor dust to more strongly resemble bacterial communities found outdoors.

Dr Fahimipour said: “Our study supports a century-old folk wisdom, that daylight has the potential to kill microbes on dust particles, but we need more research to understand the underlying causes of shifts in the dust microbiome following light exposure.

“We hope that with further understanding, we could design access to daylight in buildings such as schools, offices, hospitals and homes in ways that reduce the risk of dust-borne infections.”

The researchers warn that homes and offices may contain architectural and geographical features that produce lower or higher dosages of light which would produce different results.