In order to start addressing this question, we have to paint the picture of what really happens to the microbial flora on someone's hands between the time that someone enters a washroom, and then leaves.
It is widely accepted that hands become contaminated with microorganisms after using the toilet - this is why we wash our hands (Han et al., 1986). So the point of interest here is what happens after washing our hands, and then leaving the bathroom. Essentially, is it possible that the way we dry our hands leaves us susceptible to exiting washrooms with germs such as coronavirus on our hands?
Different hand-drying methods are thought to have different effects on the bacterial/viral loads on our hands after drying (Montville, Chen and Schaffner, 2002). For example, using paper towels to dry our hands likely has a different effect to use of hand dryers. A group of scientists in Canada set out to investigate these differences, by examining the virus and bacterial load on people's hands after they dried them via different methods (Ansari et al., 1991). This study consistently found that use of warm air drying, as opposed to paper or cloth towels, resulted in the lowest number or virus' and bacteria on people's hands. Similarly, another study found that numbers of bacteria remaining on washed hands was significantly lower for those who used a jet air dryer, leading them to conclude that this method of drying reduced the risk of infection transmission via touch (Mutters and Warnes, 2019). Furthermore, Yamamoto, Ugai and Takahashi (2005) conducted a similar study and found again that hand dryers led to the most significant reduction in bacteria on hands. In addition, another interesting find from this study was that hand dryers making use of UV light technology further assisted in this bacterial removal- see the Sterillo for more details.
What does this mean for Covid-19?
With the focus of the governments campaign being centred around direct transmission (hand to hand or surface contact), finding ways to leave bathrooms with our hands as virus free as possible is vital (Ansari et al., 1991; Otter et al., 2016). Coronavirus is able to survive on surfaces for a long time after they are first contaminated, meaning that clean hands are crucial to maintaining a sterile environment (Otter et al., 2016). This is a problem for people leaving washrooms and touching surfaces (the bathroom door handle, car steering wheel, their phones) as it is thought that this could be the predominant way respiratory virus' like coronavirus infect people (Boone and Gerba, 2007; Spicknall et al., 2010).
Why do dryers leave hands cleaner?
What is really going on whilst we dry are hands that leaves those who use hand dryers cleaner and more germ free? Some new research suggests that when water is forcefully blown off of our hands by a dryer, this is creating tiny droplets of water that may contain the bacteria and pathogens from our hands (Redway and Kimmitt, 2015). One study in particular has shown that many kinds of bacteria (even the harmful types) can indeed exist in the bathroom air as 'spores' or aerosolised pathogens which are then able to deposit on washed hands (Alharbi et al., 2016; Best, Parnell and Wilcox, 2014). The jury is still out on whether this occurs in everyday bathrooms or not. Given this area is still relatively 'unknown', the only way to truly maintain a safe bathroom environment is to fully sterilise the air with proven technology such as UVC light. The Sterillo hand dryer is the cleanest hand dryer in the world. It continuously disinfects the air in the bathroom. This means that the airborne germs potentially being blasted off of people's hands are rapidly killed and transmission of germs of even subsequent infection is prevented.
The Sterillo Duo
Our best hand dryer for beating Covid
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