ECJ EUROPEAN Cleaning Journal

A new study carried out in the UK and funded by the European Tissue Symposium (ETS) has concluded jet air and warm air hand dryers have a greater potential to contaminate washrooms by spreading bacteria into the air and onto bystanders.

Designed and led by expert medical microbiologist Professor Mark Wilcox of University of Leeds and Leeds Teaching Hospitals, the study compared the propensity of three commonly used methods of hand drying to aerosolise bacteria. Jet air dryers were found to disperse more bacteria-carrying droplets and spread them further than either warm air dryers or paper towels. 

And bacteria were found to persist for a longer time after the jet air dryer stopped.

Gloved hands were contaminated with a harmless strain of Lactobacillus, an organism not normally found in washrooms. This was done to mimic the bacterial burden on poorly washed hands. Subsequent detection of Lactobacillus in the air proved it must have come from the hands during drying. Researchers measured the air around the dryers and also at one and two metres away.

Bacterial counts in the air close to jet air dryers were found to be 4.5 times higher than around warm air dryers and 27 times higher compared with using paper towels.

Next to the dryers, bacteria persisted in the air well beyond the 15 second hand drying time, with approximately half (48 per cent) of the Lactobacilli collected more than five minutes after drying ceased. Lactobacilli were still detected in the air 15 minutes after hand drying (20 per cent of the total recovered lactobacilli for the jet air dryer).

"It is not acceptable to have contaminated air in washrooms," said Marc Van Ranst, professor in virology and chairman of the Department of Microbiology and Immunology at the University of Leuven in Belgium. "In hospitals where both medical staff and the general public share facilities, we need to be confident that equipment minimises the spread of infection in order to avoid cross contamination to the wider hospital environment."

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