Methods: A gloved rubber hand was made and four fingers fitted with rings (loose, snug, tight, and with stone setting) or no ring, dusted with simulated microbes, and washed with a scrub brush for 5, 15, and 25 seconds under 20°C and 40°C water alone, or with liquid hand soap. Light levels (in lux) of fluorescent powder before and after washing were measured. An alcohol-based hand sanitizer alone was used as a control. Univariate 2-way ANOVAR with Tukey's HSD of before-and-after differences was done of 3 replicates of both sides of the hand (n=72).
Results: Longer rinses were more effective than shorter rinses (p=0.001), 40°C water was more effective than 20°C (p=0.001), and soap was more effective than water alone except at 5 seconds. All methods were equally effective by 25 seconds. Loose and perforated rings accumulated more simulated microbes which were easily rinsed away. Alcohol-based hand sanitizer showed no change because simulated microbes were only redistributed.
Conclusions: The most effective treatment was washing with warm water and liquid soap, except cold water alone at 5 seconds. Longer times were more effective. The palm was easier to clean than the back of the hand because of loose or perforated rings facing the back of the hand.