sanitation cheat sheet


Over the last couple of weeks, sanitising has suddenly become an important topic. But with a constant stream of information and opinions in the media, how does one boil it down to simple, actionable information? Here are a few things to keep in mind:

How Long Does the Virus Stay Active on Surfaces, Really?

According to a study in the New England Journal of Medicine, the virus can stay active on plastic surfaces for up to 72 hours, with surfaces like stainless steel and cardboard reducing that number down to 48 and 24 hours, respectively. That is a scary fact. But there is good news: According to the Johns Hopkins information hub on COVID-19, infection potential dramatically degrades over the course of these windows:

“What’s getting a lot of press and is presented out of context is that the virus can last on plastic for 72 hours—which sounds really scary. But what’s more important is the amount of the virus that remains. It’s less than 0.1% of the starting virus material. Infection is theoretically possible but unlikely at the levels remaining after a few days. People need to know this.”

-Carolyn Machamer, Professor of Cell Biology at Johns Hopkins University

When it comes to air transmission, the story is similar. While the virus can remain in the air for 3 hours under controlled laboratory conditions using aerosols, real-life situations will decrease this time window significantly as cough or sneeze droplets quickly drop below face level. However, this still doesn’t mean you are safe from transmission via the air. In essence, the official recommendations for social distancing are based on the belief that the most common mode of transmission occurs via respiratory droplets while within six feet of an infected person.

Why You Need to be Aware in Public Bathrooms and Transportation

Public transportation and restrooms both create high-risk conditions for multiple reasons:

  1. Exposure to a large number of people.
  2. Limited or no capacity to maintain distance from others.
  3. Limited ventilation (aeroplanes are actually an exception due to effective air filtration).
  4. Presence of high-touch surfaces that are often necessary to use: e.g. door handles, faucets, subway kiosks, paper towel dispensers etc.

Certain surfaces are more susceptible than others. Transportation and public restroom surfaces should be treated as high risk due to the high volume and frequency of potential for contamination. Since the transmission of SARS-CoV-2 germs usually occurs when a person comes in contact with an infected person’s respiratory release/droplets, bathrooms make an easy target for the infection to spread. The layout of restroom areas will severely limit one’s ability to maintain a distance from others. And while you may feel relatively safe isolated in a stall, surfaces of toilet and stall door hardware are highly suspect. They are undoubtedly touched before occupants have had the chance to wash their hands.

While avoiding touching surfaces like handrails, doors and other fixtures is possible for young people, the same precaution cannot be taken by the elderly, who have unfortunately proven to be more vulnerable to this virus. Current CDC reports indicate that the current risk is greatly elevated for people aged 85 or older, with mortality in that age bracket currently reported as somewhere between 10%-27%. People who have limited physical abilities or handicaps should take special precautions when they find themselves relying on handrails or other surfaces to get around.

How Soap Removes Viruses

We all know oil and water don’t mix. But it turns out the oil on one’s skin, which is where bacteria and viruses find a place to camp out, is no exception to this rule. So it has to be circumvented, and that’s where soap comes in.

Soap works for removing germs because of its surfactant properties. Surfactants are compounds that lower surface tension between two agents (in this case, water and the skin’s natural oils). Because water and oil don’t usually mix, rinsing with water can’t consistently move germs because it merely glides over your skin’s oil.

As a surfactant, soap acts as a middleman between water and the body’s natural oil that binds together the otherwise irreconcilable agents. Once bound to water, oil can effectively be removed from your skin, taking microbes along with it. 

Although it’s usually stated that you should wash your hands with warm or hot water, this may not be as important as we think as the temperature of the water does not appear to affect microbe removal. Washing with soap doesn’t kill germs and viruses – instead, it simply removes them and sends them down the drain. 

The primary reason lukewarm water temperature is recommended isn’t because it kills germs but is instead, to encourage you to spend more time washing. Too hot or cold may have you bailing out preemptively. It’s widely agreed upon that you should ideally spend twenty seconds or more washing your hands to ensure effectiveness. A trick is to sing the “Happy birthday song” twice to yourself to make sure you spend enough time washing. How much time should you spend drying your hands? However much time it takes to think of a less annoying song to sing to yourself for twenty seconds next time.

How Hand Sanitisers Kill Viruses

So soap just removes viruses. But what if you are feeling vindictive? That’s where an alcohol-based cleanser comes in. 

While the unique smell of hand sanitiser brings to mind a cocktail of biocidal chemicals, the agent that kills germ is still just alcohol. Other chemicals are mainly added to prevent your skin from drying out as much as it would if you used 200 proof. Alcohol cripples microbes by denaturing their proteins, essentially causing them to unfold and become tangled up. The bad news is that if the initial tidal wave of alcohol doesn’t kill them, they will probably invite their friends over and have a giant party with the leftovers.

That’s actually just a partial joke – alcohol is ineffective at killing some types of bacteria and viruses; particularly “unenveloped” types. Fortunately, the SARS-CoV-2 coronavirus is not one of these and is therefore vulnerable to hand sanitisers. But if you want to be as thorough as possible at removing anything that may be problematic, you’ll still need to go for soap.

Hopefully, these tidbits instil a sense of confidence that COVID-19 isn’t entirely out of our realm of control. While it’s global impact has undoubtedly been significant in multiple ways and isn’t to be ignored, the good news is that with some reasonable steps and understanding; we can significantly reduce our likelihood of contracting the virus and thus, its overall impact on those around us.