April 3, 2008
Can the process of drying hands that have just been washed actually contaminate them? Is the air discharged from hand dryers cleaner than paper hand towels? The purpose of this study is to determine whether the air discharged from hand dryers is microbiologically contaminated, and to compare this result with that for paper hand towels. The test sites, i.e. public washrooms, were selected so as to represent different situations:
o Department stores
o Shopping centres
Hand towels vs. dryers
• 90% more bacteria were found on the paper towels than in the hand dryers.
• Paper towels were highly contaminated and could be a major vector of bacteria in food.
• Hand dryers contain up to 95% fewer contaminants than paper towels. Room air vs. air discharged from the hand dryer
• A reduction of up to 74% in yeasts and moulds was observed between the room air and the air discharged from the hand dryer.
• 37% reduction in overall bacteria.
• 40% reduction in yeasts, on average.
• 17% reduction in moulds, on average. Based on these results, the air discharged from hand dryers is cleaner than the room air (the air entering the device).
• There is no significant difference in the results for the various models of hand dryers.
The heated air exiting hand dryers is a natural barrier against microorganisms, i.e. it has a lethal effect that paper towels simply do not have.1 Even if not maintained, hand dryers are still the best choice, by far.
Based on the study results, the following conclusions can be made: • The air discharged from the hand dryers contains fewer microorganisms than the room air.
• The paper towels were moderately to highly contaminated with bacteria, whereas the air from the hand dryers contained significantly fewer of these microorganisms.
• There was no difference observed between the various dryer models.
• As is the case for paper towel dispensers, it was found that hand dryers require periodical maintenance in order to preserve their initial performance level.
• An unmaintained or poorly maintained paper towel dispenser can be a major source and vector of bacteria on hands.
1Hand Dryer and Hygiene, A definitive statement on the bacteriological safety of warm air.