A study published earlier in 2019 in the mSphere journal surprised a lot of people by making the case that soap and water are better than hand sanitizer for preventing the spread of flu. In fact, the study was the talk of the town when it was first released. Its data contradicts what a lot of people believe about hand sanitizing as compared to hand washing.
This post will explain why soap and water are better from a chemistry standpoint rather than a medical one. The purpose is to help readers understand what really occurs when hands are washed. Before we get to that, however, let’s briefly discuss the previously mentioned study.
The study was carried out to determine the effectiveness of both soap and water and hand sanitizer in combating the spread of influenza. By subjecting participants to contaminated mucus and then having them try both methods of cleansing, it was determined that washing with soap and water is far more effective. Surprisingly, water temperature doesn’t seem to be an issue. Effective hand washing is all about the amount of time spent scrubbing with soap.
The Mechanics of Soap
Now, let us get into the chemistry. Soap is considered a surfactant because of what it does. A surfactant breaks the chemical bond between two surfaces. Let’s say you have a bit of dirt stuck to your hands. The dirt is stuck because a chemical bond has formed between the dirt molecules on the surface of your skin. A surfactant – like hand soap – breaks that bond and allows water to get between the dirt molecules and your skin.
An added benefit of a good surfactant is that it attracts the molecules it is designed to release. Dirt molecules are actually attracted to the soap so that they are washed away in the flood of water when you rinse your hands. The longer you scrub with soap on your hands, the more dirt molecules are released and washed away.
This principle works with viruses and bacteria as well. A good soap breaks the bond, attracts the viruses and bacteria to it, and carries them away with running water.
What Hand Sanitizer Does
Hand sanitizer is merely a disinfectant. It essentially kills germs. Here’s the problem: while a good hand sanitizer can kill up to 99% of the bacteria you might be exposed to on any given day, it does very little about viruses. Most viruses can escape the killing effects of hand sanitizer. By the way, so can a small number of exceptionally robust bacteria normally found in hospitals.
Viruses that do not succumb to hand sanitizer, like the flu virus, can be passed from person to person regardless of how frequently hand sanitizer is used. On the other hand, the flu virus finds it a lot more difficult to withstand the chemistry of washing with soap and water. A good washing can effectively rid the skin of the flu virus.
According to nationally known linen and janitorial supply company Alsco, it is still important for commercial property owners to make sure all public restrooms are equipped with soap dispensers in addition to running water. Hand sanitizer certainly has its place, but nothing can take the place of a good hand washing.
Hand washing in a public setting is enhanced when paper towels are made available instead of roll towels or air dryers. Paper towels do the best job of preventing the spread of airborne germs following proper hand washing procedures.
And now you know. Hand sanitizer is good, but soap and water are better.