To do so, they examined 36 bathrooms across the campus. They were specifically scanning the areas for bacteria colonies and a lab-engineered strain of bacteria called Bacillus subtilis or PS533, often found in soil. Using a special plate, they powered on the dryers for 30 seconds to find out which bacteria spewed out.
After analyzing the results, they found 18 to 60 colonies of germs and discovered every bathroom contained PS533, which they believe likely came from a nearby lab. Although the U.S. Food and Drug Administration recognizes Bacillus subtilis as safe for humans, their findings are still concerning.
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“These results indicate that many kinds of bacteria, including potential pathogens and spores, can be deposited on hands exposed to bathroom hand dryers,” they wrote, “and that spores could be dispersed throughout buildings and deposited on hands by hand dryers.”
As the dryers blast out air, they also suck up bacteria from the bathroom, which can fester inside the device and be blown out onto the hands. The germs can then travel between rooms of a large building.
Therefore, they concluded that “hand dryers is a possible mechanism for spread of infectious bacteria including spores of potential pathogens if present.”
The scientists have also explored the capabilities of high-efficiency particulate air (HEPA) filters. While they were able to block out 75 percent of the bacteria, they have added paper towels to all of the bathrooms included in their investigation.
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