A study published recently in the Journal of Hospital Infection compared the effect of hand-drying methods on the potential risks of pathogen dissemination. A comparison was made between hand drying using paper towels (PT) or jet air dryer (JAD; Dyson) and their impact on the contamination levels in the bathrooms in several European countries.

While much attention is being paid to hand washing methods, less attention is being paid to optimal hand drying methods. Hand drying can play a key role in the prevention of the transfer of microorganisms among people and their dissemination in the environment. The relative risk of dissemination of microorganisms that are not removed from hands during washing, and remaining on the wet hands, was studied.

The main reason to use hot air dryers is to reduce paper waste. However, several studies have shown that some hand-drying methods are linked to create a greater risk of dissemination of residual microorganisms from hands after (particularly suboptimal) hand washing.

The study found lower contamination in PT versus JAD bathrooms. JAD dispenser resulted in a significantly higher total bacteria count on the dispenser surfaces than PT in all sites (median: 100–300 vs 0–10 cfu; all P < 0.0001).

Considerably more bacteria were recovered from bathroom floors using JAD (median: 24 vs 191 cfu, P < 0.00001) in the UK and France. Recovery of Methicillin-susceptible Staphylococcus aureus was three times more frequent and six-fold higher for JAD vs PT surfaces (both P < 0.0001) in the UK. Meticillin-resistant S. aureus recovery was three times more frequent (21 vs 7 cfu) from JAD versus PT surfaces or floors. The data from this study shows that 80% of airborne bacteria were recovered in the first 10 of 15 min following use of a JAD.

Enterococci and Extended-Spectrum β Lactamase (ESBL)-producing bacteria were significantly more frequently recovered from JAD versus PT washroom floors (P < 0.0001) in the UK. In France, ESBL-producing bacteria were recovered from dust twice as often during JAD versus PT use. There was also the higher recovery of ESBL-producing bacteria from floors of JAD washrooms. There were other significant differences in surface bacterial contamination, with higher levels of JAD versus PT bathrooms (e.g. higher faecal and antibiotic-resistant bacteria).

JADs dry hands via high-velocity shearing forces that remove both water and bacteria from hands, propel them into the air and on to bathroom surfaces. By contrast, PTs absorb water and bacteria with consequently less potential for bacterial contamination of the environment.

This data is in agreement with other studies. As a result, electric hand dryers are not suited to clinical settings, and perhaps inappropriate for food manufacturing facilities. During the flu season, when there is high influenza and norovirus activity, airborne dispersal of pathogens, could be a public health concern.

The study found clear differences in environmental bacterial contamination, between the two hand drying methods. With JAD showing higher levels of contamination, more spreading of bacteria, more Enterococci, MRSA and ESBL-producing bacteria than PT. Therefore it is difficult to rationalize a hand-drying method that is associated with considerably greater susceptibility for microorganisms’ dispersal when potential pathogens are potentially present.

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