0
0
Whether you wash your hands with cold or warm water after using the toilet does not matter. What matters is the duration of the washing process and the use of soap. Viennese hygiene experts have now proven this in an experiment with test subjects.
“Hand washing is an important public health measure to prevent communicable diseases such as gastrointestinal and respiratory infections. The washbasins in public toilets are often only equipped with cold water. It can be observed time and again that users only rinse their hands briefly after using the toilet instead of washing them properly with soap,” wrote Romana Kordasiewicz-Stingler from MedUni Vienna’s Institute of Hygiene and Applied Immunology and her co-authors in a recent publication by the German Society for General and Hospital Hygiene.
Trial with E. coli bacteria
As there are no recommendations regarding the optimum water temperature for the effectiveness of hand washing, the experts explained the initial situation by comparing the effectiveness of simple hand washing with cold (four degrees Celsius) and warm (40 degrees Celsius) water for ten and 20 seconds. The organization of the experiment: test persons formed five “treatment groups” with three participants each. They contaminated the fingertips of their hands by immersing them in water contaminated with E. coli bacteria. The hands were then allowed to dry, followed by hand washing with cold or warm water for varying lengths of time, etc. The bacterial contamination was measured before and after this. E. coli germs are classic intestinal bacteria and trigger diarrheal diseases, etc.
The study’s primary results were that washing hands with cold water for ten seconds reduced the germ concentration by 1.93 powers of ten (two powers of ten: minus 99 percent). There was no statistical difference to using water at 40 degrees Celsius (minus 2.01 powers of ten). The situation was similar for washing for 20 seconds (cold water minus 2.23 powers of ten; warm water minus 2.39 powers of ten). However, the more substantial effect of washing hands for longer was already statistically significant compared to just ten seconds.
However, all test arrangements were statistically inferior to washing hands with soap for one minute. The number of germs on the fingers was reduced by 2.68 powers of ten.
Hand washing for ten or 20 seconds with cold (…) or warm water “was significantly worse than the one-minute reference procedure of hand washing with Sapo kalinus (potassium soap; note), but there were no significant differences between the use of cold or warm water in a pairwise comparison for both times. However, duration appears to affect germ reduction, as the differences between hand rinsing times were significant for both temperatures,” the scientists stated in the summary of their study.
