A new paper in the Journal of Applied Microbiology demonstrates that not all methods are created equal. And the differences are not what you might expect. Rather, they have to do with the extent to which bacteria and viruses become airborne based on the method- paper towel, warm air dryer or jet air dryer –that you use. The authors demonstrate that the jet air dryer they use results in a much higher concentration of bacteria in the air than other methods. This bacteria persists up to 1 meter away from the dryer in the air for about 10-15 minutes. The paper has some notable and surprising issues with statistical replication (there is spatial and temporal autocorrelation in the data and t-tests are incorrectly applied) that detracts from its credibility, but the data largely speak for themselves.
The implication of the study is that it is not in our best public health interest to use jet air dryers given their potential for disease transmission. There is now a critical need for additional studies with added realism – does replacing paper towel with jet air dryers in an entire university increase disease transmission?
I was excited by the advent of jet air dryers, particularly given the ecological implications of using paper towel, but this will certainly warrant our attention on a hot crowded planet.
Kimmitt PJ & KF Redway. 2016. Evaluation of the potential for virus dispersal during hand drying: a comparison of three methods. Journal of Applied Microbiology 120:478-486.