Sodium hypochlorite can actually be found in trace amounts of the immune system. So it actually isn’t such a surprise that bacteria has a canned defense mechanism for when it puts stress on its proteins. But just because it exists in nature doesn’t mean you don’t have to be extremely careful with it. Breathing its fumes, coming into direct contact with it or mixing it with other cleaning chemicals will all have extremely detrimental, if not lethal effects.
The broadly applicable effect makes it work against a large variety of microbes, ranging from a variety of bacteria to viruses. Bleach is ideal for commercial cleaning applications like bathroom cleaning regimens in hospitals or public places. For this reason it remains one of the best disinfectants, so long as proper precautions are taken when using it.
How Soap Removes Germs
Soap is such a common thing we use that at some point you’ve probably asked yourself why it works and felt silly for not knowing. Considering how long it has been in use, soap hasn’t really changed much. While some ingredients have changed, the basic concept has always been to clean surfaces and ourselves by leveraging its unique germ fighting properties.
The way that soap fights germs might not be what you think. Instead of killing them, it actually simply removes microbes and sends them down the drain. This means both bacteria and viruses. The way it does this is actually by lifting oil away from your skin. While this oil is completely natural and not necessarily unhygienic, it does provide a location for microbes to stick to. Periodically washing your hands takes care of this.
So if soap works by removing bacteria, why does everyone always say to rinse with lukewarm or hot water? Simple: because it’s more comfortable. And if your hands are comfortable you are more likely to come closer to the ideal 20-30 second time window of hand washing that is recommended by the CDC. The CDC actually makes a point of saying that temperature doesn’t seem to affect microbe removal. So if you are comfortable washing your hands in cold water and would rather not use up any extra time, water and electricity while waiting for the faucet to run warm, there is nothing to worry about.
So if the objective is just to wash germs away, why not just rinse with water?
While rinsing alone may have some beneficial effect, it doesn’t consistently remove germs because water can’t do much with the natural oil on one’s skin. This is where soap’s unique chemical properties as a surfactant comes in.
Surfactants are compounds that act as intermediaries between two otherwise irreconcilable agents: in this case oil and water. Since oil and water don’t mix (the oils on your hands being no exception), soap creates conditions in which they can actually bind together and thus be washed away effectively by running water.
How Hand Sanitizer Removes Germs
Alcohol-based cleansers are a whole different story from soap. Instead of washing away germs, they wipe them out where they are at and then evaporate away without a trace. But how do they do this?
The primary active ingredient in hand sanitizer is alcohol: either ethyl alcohol or isopropyl alcohol. They have slightly different properties but both kill bacteria and viruses in the same way: by denaturing proteins and enzymes in the microbes. This denaturing process causes existing molecular bonds to unravel and become tangled up in new bindings with the alcohol itself, essentially tearing apart the microbes. And if it fails to kill them, it will at least cause them to make some poor decisions.
You’ve probably heard people say “use hand sanitizer when you have to, but nothing beats good old soap.” But why is this the case? Is soap really better than hand sanitizer? It turns out there actually is a good reason for saying this.
Hand sanitizer has some limitations in what it can kill. There are some kinds of microbes (namely “unenveloped” varieties) that are resistant to alcohol-based cleansers. Fortunately, the SARS-CoV-19 virus that is causing the current COVID-19 pandemic isn’t one of these and therefore can be killed with hand sanitizer. But if you want to be thorough, soap is still the best choice. It also has the additional advantage of washing away any dirt off the hands that could otherwise provide a safe haven for germs to hide out.
So what’s the bottom line?
Deep cleaning public facilities is a different story, but when it comes to keeping your hands sanitary, it’s pretty clear that soap is the best choice for washing your hands when it is available. But since you can’t bring running water with you everywhere you go, hand sanitizer can be pretty darn handy.