WCH CONNECTMarch 16, 2020

COVID-19 (Coronavirus) safety: Answering your questions about wearing surgical masks

  • March 16, 2020
  • BY WCH Staff

womanMaskWeb.jpgAs you have likely seen, there has been quite a bit of media coverage about masks and we have seen an increasing number of people wearing them on our city streets and asking for them when they arrive at our hospital. So, we asked Dr. Michael Gardam, our IP&C physician lead, to answer some of the most common questions about masks and who should wear them.

WCH: What are surgical masks good for?

Dr. Gardam: The original, and main purpose of surgical masks, was to catch droplets from the person who is wearing it—so they are used in the OR to prevent the operative team from breathing organisms into the sterile field. They have also been shown to decrease transmission to others if we get sick people to wear them—the mask soaks up the large droplets when someone coughs and prevents them from travelling through the air.

For droplet transmitted diseases such as respiratory viruses, surgical masks also act as a physical barrier to stop large particles coughed up by someone else from impacting on the wearer’s mouth and nose. These large particles follow a “ballistic trajectory” meaning that they shoot out straight ahead and are pulled down by gravity like a bullet. They don’t change course or follow air currents. We combine a surgical mask with eye protection to make droplet precautions.

What surgical masks are not good at is stopping truly airborne particles, which are very small and get moved around by air currents.

WCH: Does wearing surgical masks while walking down the street do anything?

Dr. Gardam: The short answer is no. Despite multiple studies, healthy people wearing masks, even in households where somebody else is sick, don’t do very much. Wearing one walking down the street is even less effective because the risk of getting infected while walking down the street is lower.

Having a sick person wear a mask makes sense and is the reason why we ask patients who are experiencing respiratory symptoms to wear one when they’re at WCH for an appointment.

WCH: Who should wear a mask?

Dr. Gardam: The only people who need to wear a mask in a hospital setting are patients who have respiratory symptoms and the physicians and clinicians who are caring for them. There is no need to wear a mask in a day-to-day setting in the hospital.

WCH: What is the advantage of N95 respirators?

Dr. Gardam: N95 respirators come from the world of industrial hygiene (which is why you can buy them at Home Depot!). They have been adopted in healthcare because they can filter out airborne-sized particles. N95s offer no advantages over surgical masks when it comes to large droplets, only the tiny airborne ones. Interestingly, a study done after SARS showed that N95 respirators and surgical masks were equivalent in protecting healthcare workers against SARS infection—suggesting that most of the transmission of SARS was due to large droplets, not the airborne ones.

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