The messaging on masks has been very confusing. For several weeks, the CDC said the public doesn’t need masks, then finally, the surgeon general was demonstrating how to make a mask out of a T-shirt. I’m convinced that the CDC was so slow to recommend masks simply because they have been so hard to come by. But the delay in recommending masks has caused a lot of confusion.
First, let’s talk about the words you’re hearing now!
Cloth Face Covering: A “cloth face covering” (I’ll say CFC for short here) is not technically a mask as the CDC defines it, and is not considering Personal Protective Equipment (PPE) from a medical perspective. This a t-shirt, bandana, buff, or anything else that can be used to cover your nose and mouth. The virus can still get both into your nose or mouth, or leave your body through these coverings, but it’s much better than nothing. A lot of people who are trying to be responsible, but can’t find a mask to buy, are using these coverings. If you hear someone saying they don’t work, they mean that they aren’t completely effective, but they are much better than nothing! Even if you sneeze, a face covering will capture larger droplets, slow the velocity of the sneeze, and help protect those around you. If all you have is a CFC, you should still wear it when you go out!
Face mask: A “face mask” is a filtering mask that covers the nose and mouth, but does not seal around the nose and mouth. This includes the blue surgical mask that you see a lot of today. These masks are designed to prevent material from medical worker’s face and nose from getting to a patient during a procedure, while still allowing somewhat normal breathing. They filter incoming air to some degree, but there are large gaps at the sides of the mask, so there are not very effective at preventing infection by SARS-2. Coughing, sneezing and singing will still expel air from the sides while wearing these masks! They aren’t completely effective, but they are certainly better than nothing, and will prevent transmission through simple talking. If you have one, please wear it!
According to Fischer et al, gator style masks may be even worse than wearing nothing at all, since they may break up droplets into a smaller size that stays in the atmosphere longer! So avoid a neck-gator style mask!
Respirator: These masks seal against the sides of the face cover at least the nose and mouth. They are designed to filter the air and prevent particles from entering the nose and mouth. N95s prevent 95% of viruses from getting through and are the preferred mask for medical workers in most situations right now. Unfortunately, they have been in very short supply since the beginning of the pandemic, so the public is being asked not to purchase these for now. Doctors tells me that N95s are not adequate protection while performing certain procedures on COVID patients! One told me a story about 14 medical workers being infected by a single patient during a procedure! This work requires a Powered Air-Purifying Respirator (PAPR). These masks cover the entire face and also blow air into the mask, pushing virus out.
If you have an N95 with a valve in the front, these masks will still vent air when you cough or sneeze, so be aware that it will not protect others from virus coming from you! N95s with no valve are the best choice for protecting both you and those around you. Again, hold off on purchasing these until there are in greater abundance.
I see a lot of very nice looking fitted masks with a little round filter in the front. These filter out large particles like dust or large droplets, but not necessarily small virus particles. While much better than nothing, these are not necessarily N95 masks! Read the product information carefully when buying these masks.
KN95 Masks: A new style of mask is being sold in the US now, labeled KN95. These masks are made in China and designed to filter out 95% of viral particles, like N95s. However, they are certified by a Chinese agency, and not by the FDA or CDC. They have been allowed to be sold in the US on an emergency basis. Users say they fit more loosely than N95 masks.
There are lots of studies showing the effectiveness of these masks, and unfortunately I don’t have one ultimate study to share with you. Suay, a clothing company in LA, did a study suggesting that normal blue shop towels (like Tool Box Shop Towels or Zep Industrial Towels) do a much better job at filtering than cotton, and are a cheap and available alternative to an N95 when sewn into a mask. My sister-in-law Penny is part of a team that makes masks for the local hospitals in Bozeman. These are homemade masks with a pocket for a HEPA filter. She’s sending me some, and I’m going to add a Shop Towel to mine! Both designs are posted below.
Here’s a few tips for wearing your mask:
- Your CFC or mask must cover your mouth and nose. Leaving your nose hanging out, or simply wearing it as a chin mask is not adequate!
- When adjusting your mask assume both your hands and the mask are contaminated. Wash your hands before AND after adjusting.
- 30 min of UV light effectively kills SARS-2 virus. In the bright sunlight, it may only take a few minutes. I sterilize my mask by leaving it in the sun for a half hour after a shopping trip. If you have a cloth face covering or mask, machine washing is a better choice.
In addition to preventing infection, masks appear to reduce the viral load in newly infected patients, leading to less severe symptoms! So even if you get infected while wearing a mask, your symptoms are likely to be less severe!
As we think about re-opening the economy, face coverings, even the bandana type, will really help keep new infections low. So wear a mask when you go out in public! Any improvements will hasten the day when businesses can re-open. I am awaiting data to see what the infection rate is at businesses in which employees wear masks. Hopefully, this data will come out soon.
I just started working on a COVID testing project full-time. This means I will be less available to blog for the next few weeks or months. I will certainly keep blogging, but won’t be as able to respond to questions, or read submitted articles.
Don’t fear, but be smart!
Masks effective in protecting healthcare workers, Bartoszko et al.
Study on the best masks, Fisher et al.
Mask may reduce symptoms and even provide some immunity, Ghandi et al.