Keeping the curtains open helps to kill bacteria in household dust

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 in dust.

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

Dr Ashkaan Fahimipour, the study’s lead author, 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.”

Researchers made 11 identical climate-controlled miniature rooms that mimicked real buildings and seeded them with dust collected in residential homes. 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. 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 than in dust not exposed to light.

Dr Fahimipour said: “Our study supports a century-old folk wisdom, that daylight has the potential to kill microbes on dust particles.”

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