One of the main questions and concerns Delta County Memorial Hospital (DCMH) has heard from community members is in regards to mask wearing and mask safety. Sara Knutson M.D., DCMH Pulmonologist and Planning Section Medical Director for the Hospital Incident Command team, answered your top questions.
Q: There is a lot of conversation around masks lately, and it’s hard to know what to believe. What is science and what is fact? Do face masks and coverings
really
even work?
Dr. Knutson:
Mask wearing is a freebie in the fight against COVID-19 infection. It is a cheap, non-painful way to protect the vulnerable ones you don’t want to infect, because they can do poorly. And it is an easy way to help your county hospital weather the COVID pandemic, so the hospital space, supplies, and staff don’t get maxed out. The overwhelming body of scientific evidence that has accumulated over the course of these past few months suggests that mask wearing offers significant benefit in stopping the transmission of COVID-19.
Q: Since my cloth mask won’t filter out every last virus particle, what is the point of wearing it?
Dr. Knutson:
While not desirable, it is probably OK that occasionally a virus particle might get through your cloth mask. The lung gets infected when an infectious dose sufficient to allow the bug to overwhelm your body’s defenses to get a foothold in your system. Note that smoking also compromises your lungs’ ability to stay free of infection. While we don’t know what the size of the infectious dose is for COVID-10, we do know that when people cough or sneeze, the virus is expelled and suspended in aerosolized fluid droplets. The point of the mask is to retard the spread of these droplets, either blocking them altogether, or slowing down their exit speed. This all serves to reduce the physical spread of the virus. We don’t know exactly how much, but there is no debate whether there is some effectiveness. Anything is a gain.
Q: I see people waring face masks not just in stores and restaurants, but in their cars, on walks and in their homes. Do we have to wear masks all the time, or are there some specific occasions where the benefits of wearing them are especially great?
Dr. Knutson:
So the biggest gain from mask use is in settings with larger amounts of face to face time with multiple people in a closed space; think movie theaters, the bar scene, or any office in a waiting or meeting room. You should wear your mask when you might spread your virus particles to a hard surface that others might touch with their hands, such as a grocery, hardware store or gym. Does anyone want to eat vegetables that someone with COVID-19 has sneezed over? The answer is likely, no.
You don’t have to wear your mask in your car, or your private office, or in your home with your family. You will want to consider wearing your mask when you are spending time with people at increased risk of severe disease, like your grandmother. Jogging or taking a walk outside without your mask on, even if you are infected, are probably low risk events. The bottom line: you are wearing your mask as a courtesy to protect others. Remember that 20 percent of people with contagious COVID-19 may be asymptomatic, and infected persons are infectious up to three days before they even start showing symptoms.
Q: I’ve heard that my mask can get contaminated and actually make me more likely to get infected. Is this true?
Dr. Knutson:
It is correct that in the hospital we disinfect or dispose of our masks after use, and the CDC recommends we keep our masks private to one user. So yes, masks can become contaminated and the outside surface of the mask is something you don’t want to touch after taking care of a COVID-19 patient. But the situation with the average person in the community setting is much different. In this setting, normal practices of hygiene apply; simply toss your cloth mask into the washing machine after use (maybe have a few to rotate) dry it with the rest of your laundry, and you will be fine. It’s no different than a scarf or bandana that you might tie about your neck or mouth in a cold or dusty environment.
Q: Why are health officials and the government pushing for us to wear face masks? Why not just skip the mask and go for ‘herd immunity’?
Dr. Knutson:
Well, herd immunity would be great, but the only problem with this plan is that to get herd immunity for COVID-19 within a population, you need somewhere around 66 percent of the population to have been infected. This is calculated based on the infectivity of COVID-19, which is worse than flu, but not as bad as something like measles.
The last figures I saw in New York for the percent infected was in the low 20 percent; look at the misery it took them to get even there, and they are nowhere close to herd immunity yet. The only thing to do, especially as the reopening proceeds, is to practice sensible precautions to avoid infection: hand hygiene, mask use, social distancing, and then bide our time until a vaccine is on the horizon.
Q: When I wear my mask I feel smothered and I get a headache. I think mask use causes low oxygen and high carbon dioxide. How can this be good for me instead of breathing fresh air?
Dr. Knutson:
There is no scientific evidence that cloth mask use is harmful to your health, whether from infection or due to compromising air exchange. With the cloth masks or face coverings that we are talking about, there is a significant amount of room-air entrained on inspiration, and no significant resistance to expiration. This means the use of the cloth mask will have
no impact
on your oxygen or CO2 levels.
Upon reviewing medical literature, there are some data about the effects of N95 masks on oxygen and carbon dioxide levels (these are the masks health care providers wear during COVID care that filter ALL inspired air thru the mask pores, which also have some increased resistance to expiration and theoretically could increase CO2 rebreathing). But these are N95 masks, which are supposed to be worn only by health care personnel engaged in direct care of COVID patients, especially during high risk procedures. We don’t expect or recommend that the average citizen should need to wear an N95 mask.
When it comes to the discussion of a potential compromise in air exchange for cloth masks or face coverings, there is nothing in the literature about any effect on air exchange for simple cloth face coverings. It is important to understand that the cloth masks are a completely different animal than the N95 mask since the air you are breathing in is not being filtered through the mask, but rather entrained around the edges of the mask. You might feel the mask is stuffy or humid, or that it can even fog up your glasses.
But if you have low oxygen or shortness of breath either with or without a cloth mask, you should probably seek additional medical evaluation, as these symptoms are not due to your mask
.
Bottom line with mask use: it is a cheap and easy way to fight against spread of COVID-19. Cloth mask use isn’t harmful to the health of the mask user. It can be extremely beneficial to avoid infecting persons with conditions of increased risk for severe disease, especially in high risk settings. Wearing a mask is courteous, and reduces your chance of infecting others, especially when you don’t know that you are infectious. Recall that by the time your COVID-19 infection becomes symptomatic, you have already been infectious for up to 3 days. Mask use, hand hygiene, and distancing is a no-brainer in reducing the spread of COVID-19.
