When people hear that washing our hands is effective at removing germs, they think that the hotter the water is that they wash their hands in, the better it is for killing germs. However, this is actually not true, and in fact, hot water can be damaging to our hands.
When we expose our hands to hot water, we cause more harm than good. The hot water causes the protective layer of our skin to deteriorate, and as a result leads to more skin irritation such as redness, dryness, pain, and itching. When the protective layers are damaged, it can make a person more susceptible to the bacteria on their hands.
If you are concerned that using cooler water is not going to clean your hands well enough, don’t be. A study that was done by a microbiologist called for the microbiological swabbing of hands after they were washing in water that was 40°C as well as 60°C. Afterward, the swabbing showed that there was actually an increase in Campylobacter, E. Coli and Listeria on the hands that were washed in the 60°C water.
So, not only is cooler water better for our hands, it is also more effective at killing germs.
Many microbiologists have found that washing the hands with soap and water as cold as 40°F (4.4°C) effectively reduces bacteria if hands are properly scrubbed, rinsed, and dried.