MIT Medical answers your COVID-19 questions — and we also answer your follow-up questions! Got a question about COVID-19? Send it to us at CovidQ@mit.edu, and we’ll do our best to provide an answer.
Since reading your article on choosing the best cloth face covering, I have been struggling to find masks with multiple layers of high-density cotton that will work well for my kids and myself. But after trying six different kinds of masks, I’m discouraged. Either they don’t have a nose bridge, or they don’t fit snugly, or they’re hard to breathe through. But then I found these other masks that fit great and are really comfortable — elastic on the sides, adjustable ear loops, and a nose bridge. These masks have three layers, but they’re not made of cotton. The shell is nylon, polyester, and spandex, and the liner is 100% polyester. Will this mask work, or should I keep looking?
You are not alone in asking a question like this. Since publishing that previous article, we’ve heard from a lot of people who have been stressing out about finding “the best mask.” So, let us say this in no uncertain terms:
The best mask is the mask that you can wear comfortably and correctly for as long as you need to keep it on.
Many of us geeky MIT types are fascinated by studies of “filtering efficiency” and “maximum penetrating particle size.” Some of us even enjoy reading sentences like “In this study, FE and MPPS were determined by converting FE to penetration efficiency (PE = 100% − FE) and fit to a logarithmic bi-Gaussian distribution.” But at the end of the day, it’s important to remember that many of the statistically significant differences between masks that scientists can measure in the laboratory are unlikely to make a practical difference in our everyday life. This is particularly true if we are also taking other precautions, like physically distancing and avoiding spending long amounts of time with other people in closed, indoor spaces.
What we know for sure about face coverings is that one layer of anything is better than nothing at all. Two layers are better than one, and three are better still. Given that you’ve found a three-layer mask that fits you well and is comfortable and breathable, you’re in good shape.
If having an extra layer will make you feel better protected in certain situations, try adding a layer consisting of a folded facial tissue. As it turns out, a single layer of Kleenex has a filtering efficiency of about 20 percent, according to one study. Folding it over should improve filtering even further and shouldn’t affect breathability much at all.
Bottom line? Masks of all kinds are effective in preventing the transmission of COVID-19. Your mask protects others, and it may protect you as well. Find a mask that fits you well and that you can wear comfortably, and then make sure you use it.