How dangerous are surfaces and what can you do to be safe?

Frequently touched public surfaces like elevator buttons can carry the virus — which depending on circumstances can stay active for hours or days. (© Richard McGuire Photo)

The main way that the coronavirus causing Covid-19 spreads is by human-to-human contact.

It forms as tiny droplets when people sneeze or cough, etc. These travel through the air and you breathe them in — where they infect your respiratory system.

The recommended or required distance is two metres or just over six feet to avoid this. Aim for more if possible to be safe. And no, it’s not safe to shake hands from two metres or any distance!

But people also sneeze and cough on surfaces. They cover coughs and sneezes with their hands (why you don’t shake them) and then touch elevator buttons, card transaction machines, and all those other surfaces in our normal lives. If you handle these, then touch your face, you can get the virus. It enters through mucus membranes like your nose, eyes, mouth — you get the idea!

Washing hands thoroughly and as soon as possible after touching surfaces without touching your face is a must. But it’s hard to avoid touching faces because we do it without thinking — for some people many times in an hour.

How long does a surface stay infectious? That depends.

When the virus is gone depends on the material of the surface, whether it’s in the sun, the temperature and many other factors. It deteriorates over time.

A new study released on March 17, 2020 looked into that question of how long the virus stays active on surfaces. The study was done by National Institutes of Health (NIH), U.S. Centers for Disease Control and Prevention (CDC), University of California Los Angeles (UCLA) and Princeton University scientists in The New England Journal of Medicine.

From the news release about the study:

The results provide key information about the stability of SARS-CoV-2, which causes COVID-19 disease, and suggests that people may acquire the virus through the air and after touching contaminated objects.

Among the highlight were:

  • The virus that causes the disease is stable for several hours to days in aerosols (airborne droplets) and on surfaces;
  •  The virus was detectable in aerosols for up to three hours, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel;
  • Emerging evidence suggests that people infected with virus, known as SARS-CoV-2, might be spreading the virus without recognizing, or prior to recognizing, symptoms. This makes it harder to control than the virus that caused SARS in 2002 and 2003;
  • Healthcare settings are vulnerable to the introduction and spread of SARS-CoV-2, and the stability of the virus in aerosols and on surfaces likely contributes to transmission of the virus in healthcare settings.

See the full news release announcing the study.

See the letter in the New England Journal of Medicine (Technical and written for health professionals)


The difference between droplet contact and airborne transmission – from BC Centre for Disease Control

Droplet Contact: Some diseases can be transferred by large infected droplets contacting surfaces of the eye, nose, or mouth. For example, large droplets that may be visible to the naked eye are generated when a person sneezes or coughs. These droplets typically spread only one to two metres and are too large to float in the air (i.e. airborne) and quickly fall to the ground. Influenza and SARS are two examples of diseases capable of being transmitted from droplet contact. Currently, health experts believe that coronavirus can also be transmitted in this way.
Airborne transmission: This occurs when much smaller evaporated droplets or dust particles containing the microorganism float in the air for long periods of time. Transmission occurs when others breathe the microorganism into their throat or lungs. Examples of diseases capable of airborne transmission include measles, chickenpox and tuberculosis. Currently, health experts believe that coronavirus cannot be transmitted through airborne transmission.

Author: Richard McGuire

Richard McGuire is an Osoyoos photographer who worked at the Osoyoos Times between 2012 and 2018, first as reporter and then as editor. He has a long career in journalism as well as research, communication and management at the House of Commons in Ottawa and in the federal government.

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