The findings are said to have significant implications for infection control health professionals and purchasing managers responsible for equipping hospital washrooms.
Designed and led by expert medical microbiologist Professor Mark Wilcox, of University of Leeds and Leeds Teaching Hospitals, and funded by The European Tissue Symposium (ETS), the study was recently published in the Journal of Hospital Infection.
It compared the propensity of three commonly used methods of hand drying to aerosolise bacteria. Jet air driers were found to disperse more bacteria-carrying droplets and spread them further than either warm air dryers or paper towels. In addition, bacteria were found to persist in the washroom air for a considerably longer time after the jet air dryer stopped.
Airborne dissemination
In carrying out the study, 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 that it must have come from the hands during drying. Researchers measured the air around the driers and also at distances of 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 driers and 27 times higher compared with using paper towels. Next to the driers, bacteria persisted in the air beyond the 15 second hand drying time, with approximately half (48%) of the Lactobacilli collected more than 5 minutes after drying ceased. Lactobacilli were still detected in the air 15 minutes after hand drying (20% of the total recovered lactobacilli for the jet air dryer).
Microbial cross contamination
"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.”
Containment of infection in a hospital setting continually hits the headlines across Europe and is a priority for governments and the medical community. According to the researchers, the extent to which jet air dryers dispel microbes in the washroom environment raises questions concerning policy guidance to avoid the spread of infection in hospitals and other public environments. The data showed that hand drying with single use towels contributes least to airborne contamination and hence offers the most hygienic solution.
Professor Wilcox commented: "We increasingly emphasise the need to wash hands to control the spread of infection, but we have not considered the best way to dry them. Best does not solely mean convenience. Drying hands using electric dryers risks spreading microbes in the washroom, and this is clearly not desirable when trying to limit the spread of bacteria or viruses from person to person."
The gloves are off
Dyson, the global brand in hand dryer technology, claims the report was based on 'flawed methodology'.
A spokeswoman said: ""In fact, the Dyson Airblade hand dryers are the fastest, most hygienic way to dry hands and they produce up to 71 per cent less CO2 than paper towels and are able to dry 18 pairs of hands for the price of a single paper towel."
According to Dyson, the new research was conducted under artificial conditions and does not reflect real life. This is because gloved hands were covered with unrealistically high levels of bacteria and dried without prior washing. Dyson also said that the amounts of bacteria retrieved from the air are insignificant and presented without any real life context: more bacteria are released into the air by removing one’s jacket or changing one’s shoes than found in this study.
The spokeswoman added that the results in a real washroom look different: "People wash their hands to remove bacteria before drying them – and they don’t wear gloves. When hands are dried properly, it reduces the spread of bacteria up to 1000 times."
She concluded: "In reality, the Dyson Airblade hand dryer has been proven to be as hygienic as paper towels, through research commissioned by Dyson and published in the Journal of Applied Microbiology conducted by the University of Bradford."
Source: www.cleaning-matters.co.uk
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