In a study published in the journal Microbiome, researchers tested the germ-busting theory by setting up miniature rooms with the same conditions as a typical normal-sized indoor room—from the temperature to humidity levels—and filled them with real dust from people’s homes. After 90 days, the rooms exposed to plenty of sunlight had half the viable bacteria—AKA bacteria that are able to grow—of rooms that were kept dark. The rooms with UV lighting, in case you’re wondering, had slightly fewer viable bacteria than those with natural light—6.1 percent as opposed to 6.8 percent.
After 90 days, the rooms exposed to plenty of sunlight had half the viable bacteria of the rooms that were kept dark.
“Sunlight is a central component of architectural design and has long been considered a potential buffer against the spread of pathogens in buildings due to its potential bactericidal effects,” wrote the study authors. “These results suggest that window-filtered light exposure, regardless of the particular transmittance profile, decreases the number of living bacteria in dust communities.”
Just one more reason keep your windows streak free and let the sunshine in.