Soap: The Greatest Discovery Of All Time #ScienceSundays

by Erin

Soap. From washing our hands to cleaning the world around us it has drastically made an impact on our public health. And it’s even more important now.

Wash Your Hands


In case you don’t want to read this entire post, here’s the short version:

Wash your hands, often. Preferably with soap. Second best is a 60-95% alcohol-based sanitizer. Limit your social interactions. And wear a mask!

I feel the need to follow up my coronavirus post with another. If only to placate the misinformation at least one of you reading this has read. Or even if you know it and just need a reminder because I think we can all admit we could be better about these things.


Kids Washing Hands

My nephews being good hand washers

And yes, you should reduce large social gatherings, especially if your immune system is weak. Heck you should really just stay home if that’s the case. I myself am currently trying to convince my elderly and immunocompromised loved ones to sit tight and be extra careful. Am I afraid that I will get coronavirus? Not as much as I am afraid of giving it to someone who would be more susceptible to it.

Now that I’ve got that off my chest, let’s focus back on the #1 priority of washing your hands. People have been frantically stockpiling hand sanitizers and those without looking for at home remedies. I’ve caught several DIY hand sanitizer recipes on the internet that, while better than nothing, are not necessarily going to kill coronavirus. So, let’s talk about how these things work and what is best (soap).

There are thee common types of hand sanitizers: detergents (soap), alcohol sanitizers, and non-alcohol-based sanitizers. I will focus on the non-alcohol-based ones first and work my way back.

Purell Hand Wipes

Images provided by Hannah of

Some alcohol-free hand sanitizers contain benzalkonium chloride instead of alcohol. While these products may work for some germs, according to the CDC they might just reduce their growth instead of killing them. While better than nothing, it’s information you should know [1].

Alcohol hand sanitizers are the next step up, but still have some caveats of their own. It is important to keep in mind that how well it works depends on the alcohol content, how much is used, and the technique in which it is used.

Alcohol solutions containing 60-95% alcohol are the most effective (many DIY recipes I found were only 40%), with ethanol being the most effective alcohol against viruses and propanol more effective against bacteria. As for how much and technique, it is similar to hand washing: apply enough to cover your hands, rub all over your hands for 20 seconds or until completely dry (do not wipe off). But if your hands are visibly dirty or greasy, they may not be as effective [23].

But alcohol-based hand sanitizers don’t kill ALL types of germs. Meanwhile, handwashing reduces the amounts of all types of germs on hands [34].

Washing Your Hands

The adorable daughter of Hannah from

The CDC stands by washing your hands with soap and water for at least 20 seconds as your best bet. If that’s not possible, alcohol-based hand sanitizers with at least 60% alcohol is your next best option. What to see the studies for yourself? There is a whole slew of them [5].

Summary of the above thus far? Alcohol-free hand sanitizers are better than nothing, and alcohol-based is even better, but nothing is as good as washing your hands.

But what about cleaning household or public surfaces? The CDC says that dirt should first be removed with a detergent/soap and water prior to disinfection with diluted bleach, 70% alcohol solutions or, EPA-registered disinfectants [6]. These options should be effective against coronavirus if you pay attention to the contact time for the product (but should not be used on skin so wear gloves) [7].

Bleach Uses

A quick history lesson about germs. Did you know that before Louis Pasteur experimented with bacteria in the 1860s, people did not know what caused disease. Not only did he help facilitate this connection later verified by Robert Koch in 1876, but he also discovered that bacteria could be killed by heat and disinfectant (hence the term pasteurization). This resulted in doctors washing their hands and sterilizing their instruments, saving millions of lives [8].

Now let’s move on to masks. While one study (not yet peer reviewed) found that coronavirus can live in the air for up to 3 hours, cardboard for 24 hours, and steel/plastic for 3 days [9], this study did not identify anyone who has contracted it through breathing it in or touching a contaminated surface. However, it does show that it is theoretically possible [10]. UPDATE: Sure enough it is now thought to spread person to person mainly through respiratory droplets produced when an infected person sneezes, coughs, and talks withing 6 feet of another person [10a]. 

Do masks help? If used properly, but some are too loosely fitted. The N95 surgical masks are the most effective. But, N95 surgical masks should be prioritized for health care workers, per the surgeon general [11], so don’t hoard them! Our healthcare system is already strained enough as it is, please don’t reduce their supply of necessary items.

Initially, evidence was still accumulating and at first masks were only recommended for those at risk. However, recent studies affirm that face coverings are critical for fighting the spread of COVID-19 [11a]. A tighter fitting mask to the face is likely better, with multiple layers of tightly knit fabric [11b], but something is better than nothing [11c, 11d, 11e].

Our best option as a community of people is to practice social distancing in order to flatten the curve of the pandemic and wearing a mask when in public. That way our health systems can cope with the crisis and give time for scientists to research vaccines and treatments [12].

An real life example of how well this works can be seen in a chart of the Spanish Flu as is affected two different cities [13]. In 1918, the city of Philadelphia ignored warnings of influenza and threw a parade that results in thousands dead. By the time the city shut down it was too late. However, within 2 days of the first cases in St. Louis, the city shut down schools, libraries, courtrooms, and churches. Work shifts were staggered and public transportation was limited. Public gatherings of more than 20 people were banned. Due to such extreme measures their flu related deaths in St. Louis were less than half of Philadelphia.

Now our global health agencies are calling for it again to mitigate the spread of coronavirus. Especially to protect those at higher risk of serious illness, who are the ones who should be stocking up on supplies [14].

Speaking of, I am appalled by the selfishness of the hoarding of paper goods and cleaning products. Did you know that food pantries even in good times have limited supply of paper products and soap? Guess what items are no longer in stock there as well? How about you donate some of that apocalypse-worthy pile you have hidden in your basement?

While we have a decent stock, it is not because we rushed out and bought it, we just always have a supply. We haven’t purchased any soap/paper products in probably over a year because one trip to Costco lasts our house of two that long. So, guess what I am doing with our excess that I don’t think we will need in the next couple months? I am donating it. Because if I can help reduce the spread of coronavirus to those that need the protection most, it’s worth it.

Need to talk to your kids about it? There is a great comic that explains it, complete with a printable [15]!

And with that I am signing off with a clip from one of my favorite movies, Donnie Darko:

























Corona-Virus Sugar Cookies #ScienceSundays December 29, 2020 - 8:19 pm

[…] contract from infected surfaces. Therefore stick to the basics you should follow every flu season: wash your hands, don’t touch your face, cover you mouth when you sneeze or cough (preferably with a tissue […]

Susan March 26, 2020 - 2:09 pm

Erin, I’m one of those who could be seriously at risk – in my mid-70s, asthma, just got off a very long international flight… (business class is a life-saver, from both a comfort standpoint and social distancing). The reality of living around the virus has yet to fully hit home, but I was strongly encouraged in better habits on the ship and am working on keeping them going. I plan to stay home once I get there, and will probably send my husband out to do the grocery shopping because he is less at risk than I am. I am not ready to lose my life to such a nasty virus (no matter what the lieutenant governor of TX says about old people sacrificing their lives).

Erin March 26, 2020 - 7:38 pm

My mother is also at risk and it’s been a challenge convincing her to stay home and not invite people over, but I think she’s finally starting to get it. I am glad to hear you are taking care of yourself! (And the lieutenant governor can stuff it.)

Susan March 26, 2020 - 10:41 am

Thank you for your two posts on Corona Virus. We just got back to the US (not home yet) and need to get used to all the changes. Reading something sane, after hearing lots of rumors, is really helpful.

Erin March 26, 2020 - 10:49 am

I hope you are staying away from people as much as possible and quarantining yourself once you get home! So much of the spread is obviously linked to travels.


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