Note from Michael, Dec. 19, 2021 (Update #2) | Masks, visors and respirators, oh my!

From the desk of Dr. Michael Gardam, Health PEI CEO

Hi Everybody:

In my experience, with every new wave of COVID, the Infection Prevention and Control team faces an increase in questions regarding the appropriate PPE to wear.  This update might be too nerdy for many of you so feel free to skip to the bottom to the “what does this mean” section.  For those of you who want more information though, here it is. This summary represents about 20 years of academic fights between various camps—the airborne people and the droplet/contact people.  Like most things in life, the answer is in the middle!  Fortunately, there has recently been some compromise on both sides and my former organization Public Health Ontario recently released new guidance that has taken a middle of the road stance that recommends respirators for routine care of suspected or confirmed COVID-19 patients—not for general patient care. 

First a quick review on what we know about SARS CoV-2 transmission.  When an infected person sneezes, coughs, breathes, talks etc, they release a range of particles from visible big droplets to microscopic droplets.  The bigger they are, the more virus they contain and the more they fall to the ground.  The smaller the particle, the more likely they are to follow the air currents.  Regardless of the particle size, the closer you are to the source, the more particles there are—the particle concentration exponentially decreases at 1/radius3 meaning that there are many more particles within 1 metre than there are at 2 metres…by 3-4 metres, there are very few particles at all.  These particles gain access to your respiratory tract through your nose, mouth and eyes. The airborne particles can get right into the lungs while the larger particles tend to impact in the nose and throat and eyes.  For viral particles in your eyes, it is a short trip through your tear ducts to the back of your throat. 

The main protection strategy for the larger particles is physical barriers—masks, gowns, gloves, visors, plexiglass, along with distancing. The main protection strategy for the smaller airborne particles is ventilation and respirators (these block the small particles better than surgical/procedure masks) and distancing.  The relative benefit of respirators decreases with better ventilation, to the point where in settings with good ventilation, the respirator doesn’t add much as the particles are removed from the air with ventilation.  This is why we don’t worry about airborne transmission when people are outside. 

Real life experience supplemented with lab studies over the past 20 months has shown that SARS CoV-2 infection is predominantly through the larger droplets which makes sense as that is where the volume of viral particles is; however, the microscopic droplets can play a big role in settings where there is poor ventilation, especially if the source patient is spewing out a lot of virus.  So in a low ceilinged, crowded space with poor ventilation, airborne spread can be a significant route of transmission. Fortunately for us in healthcare, the engineering standards for healthcare facilities require higher levels of ventilation than other settings like offices, schools etc.

There is nothing to suggest that Omicron transmits in a fundamentally different way than what I described above.  Physics is physics and regardless of the variant, the same rules apply.

So what does all this mean?

  • Wear your eye protection with all patients;
  • Wear your gowns and gloves where appropriate—these measures are likely less important than protecting your face, but they are part of the whole barrier approach and we should continue with them;
  • Wear at least an appropriate medical grade mask for all patient contact ensuring it is covering your nose and mouth
  • Maintain your distance where you can; including when around your colleagues
  • Continue to do your point of care risk assessment to decide what PPE to wear. If there are concerns that a patient may have COVID-19, it is appropriate to wear a fit tested respirator or a full face/half face respirator (these are the respirators that look like gas masks. They don’t provide any appreciable protection benefit over N95 respirators and are hard to wear, but they are reusable). 

So why not just wear respirators for all patients given we are entering into a serious wave of COVID-19?
This strategy isn’t wrong, but it isn’t entirely right either. There are also things to think about that stop us from just blanket recommending this:

  • Most of you have not worn N95s for days on end.  I have, and I can tell you they become harder and harder to comply with which then starts to increase the risk of infection when they are fiddled with, removed, taken down when speaking etc.;
  • For most encounters, they won’t add significant protection—what is important is having a barrier over your mouth, nose and eyes. For aerosol generating procedures or in settings with poorer ventilation, respirators will provide relatively more benefit and this is where your risk assessment is so important;
  • While we have a good supply of respirators with more on the way, the supply chain is always a concern. Respirators are far more difficult to make than medical grade masks, and they will always be a scarcer commodity. We will be watching supply very carefully. 
  • As I said yesterday, experience over the past 20 months has shown that the vast majority of healthcare worker infection does not occur at work. I can’t emphasize this enough—you are far more likely to acquire infection from your friends, family, and during gatherings. 

Some of you will want to wear respirators for all patient encounters and that is up to you, being mindful of the points above. I suspect most of your will selectively wear them as per your point of care risk assessment and the most recent guidelines. To me, the most important point is far less about the mask/respirator in most settings, and far more about you wearing your PPE consistently and being very mindful of where you remove your mask/respirator and eye protection i.e. in break rooms. Our PPE use is of course important for protecting our patients, some of whom are not or cannot be vaccinated or are at higher risk.

I hope this helpful.  Sorry for the long update.

Please send questions, comments, or submissions for these notes to emclean@gov.pe.ca, subject line “Notes for Michael”.

Last Updated
Sun, 12/19/2021 - 17:54