Bathroom hand dryers may be blowing bacteria and faeces all over you, study suggests
They are known as ‘toilet plumes’.
Air coming out of hand dryers in public bathrooms may be doing more than just drying your hands.
According to a new study by the University of Connecticut School of Medicine in the US, dryers sucking in bacteria and faecal particles from flushing toilets can spread it onto your freshly-washed hands.
Previous research published in 2015 has indicated that flushing an open toilet allows faecal matter and bacteria to be thrown as high as 15ft (4.5m) into the air – which are known as “toilet plumes”.
The team tested 36 bathrooms at their university for a lab-engineered strain of bacteria Bacillus subtilis called PS533 and found the strain present in every bathroom tested when sampling the air for spores.
They also analysed plates that were placed under the dryers and in the bathroom, with a fan positioned next to the bathroom plates redistributing air for 20 minutes.
The researchers wrote: “These results indicate that many kinds of bacteria, including potential pathogens and spores, can be deposited on hands exposed to bathroom hand dryers, and that spores could be dispersed throughout buildings and deposited on hands by hand dryers.”
The team then retrofitted some of their dryers with high-efficiency particulate air (Hepa) filters, which saw bacteria numbers reduce four-fold.
They say the results raise the possibility of infectious bacteria being spread through public bathrooms.
The researchers added: “Within a large building, potentially pathogenic bacteria including bacterial spores may travel between rooms and subsequent bacterial/spore deposition by hand dryers is a possible mechanism for spread of infectious bacteria including spores of potential pathogens if present.”
The research is published in the journal Applied and Environmental Microbiology.
