sunlight

OPEN YOUR BLINDS

Daylight kills household germs.

THE SCIENCE
Sunlight kills bacteria living in household dust, according to a new study in the journal Microbiome. Researchers from the University of Oregon created 11 identical rooms, added dust collected from local homes, then flooded the rooms with either visible light, ultraviolet rays, or none at all for 90 days. 

Bacteria didn’t fare well in the rooms exposed to visible light: Germs survived in just 6.8 percent of the dust, compared to 12 percent of dust kept in darkness. These rooms also had the lowest count of bacteria associated with respiratory infections. 
EXPERT INSIGHT
It’s well known that UV rays kill germs by breaking up DNA in the cells, says Paula Olsiewski, Ph.D., New York City-based program director of the Alfred P. Sloan Foundation, which funded the study. But UV rays can’t penetrate window glass. The researchers were surprised to find that visible light, a.k.a. daylight, killed bacteria at almost the same rate. 

Compared to germs that come from outdoor air, those that stem from human skin are more likely to be pathogenic and less likely to survive in daylight.  
THE BOTTOM LINE
Leaving your blinds or curtains open during the day can reduce your risk of infection from dust-borne bacteria.