Effects of 4 Hand-Drying Methods for Removing Bacteria From Washed Hands: A Randomized Trial

Objective: To evaluate the effects of 4 different drying methods to remove bacteria from washed hands.
• Subjects and Methods: One hundred adult volunteers par-
ticipated in this randomized prospective study. All bacterial counts were determined using a modified glove-juice sampling procedure. The difference was determined between the amounts of bacteria on hands artificially contaminated with the bacterium Micrococcus luteus before washing with a nonantibacterial soap and after drying by 4 different methods (cloth towels accessed by a rotary dispenser, paper towels from a stack on the hand-washing sink, warm forced air from a mechanical hand-activated dryer, and spontaneous room air evaporation). The re-
sults were analyzed using a nonparametric analysis (the Friedman test). By this method, changes in bacterial colony-forming unit values for each drying method were ranked for each subject.

• Results: The results for 99 subjects were evaluable. No sta-
tistically significant differences were noted in the numbers of colony-forming units for each drying method (P=.72).

• Conclusion: These data demonstrate no statistically signif-
icant differences in the efficiency of 4 different hand-drying methods for removing bacteria from washed hands.

Mayo Clin Proc. 2000;705-708

Hand washing is the single most important procedure in hospital infection control. Many studies reported in the medical literature have shown that disease-causing bacteria are carried on the hands of health care workers. Good hand-washing techniques can prevent the spread of these bacteria to patients. Many studies have also demonstrated the usefulness of antibacterial soaps and the physical washing of the hands to remove bacteria.10-19 Fewer studies have been reported that evaluated the effect that drying the hands has on removing bacteria. The purpose of the present study was to determine the difference between the amount of bacteria on the hand before washing and after drying with 4 different hand-drying methods: cloth towels accessed by a rotary dispenser, paper towels from a stack on the hand-washing sink, warm forced air from a mechanical hand-activated dryer, and spontaneous evaporation. We hypothesized that no significant difference in bacterial reduction occurs among any of these hand-drying methods.