Importance of masks

Public health and other data strongly supports that universal masking substantially reduces transmission of COVID-19. The main purpose of the mask is to prevent the wearer from expelling small virus-containing droplets of saliva or mucus into the air and infecting others. Wearing a mask reduces the likelihood that an infected individual could spread the virus to people around them (colleagues, co-workers, friends, etc). This is especially important for infected people who may be asymptomatic.

Masks also protect the wearer. Researchers have determined that the nose is a key entry point for the virus that causes COVID-19. The publication in the journal Nature Medicine explained that nasal cells in particular contain high levels of the proteins that SARS-CoV-2 attaches to in order to enter the body.

Therefore, to reduce the spread of the virus, and to protect the health of all our faculty, staff, and trainees, WashU School of Medicine is requiring universal masking.

How to wear your mask

  • The face covering/mask should fit snugly to cover the wearer’s mouth and nose. Research on mask fitting shows that infectious aerosol exposure decreased by about 95% when masks were tightly fitted, providing roughly the same level of protection as an N95 respirator. CDC guidelines offer tips for tightening the fit of cloth and disposable masks to boost COVID-19 protection.

    The recommendations include:
    • Selecting masks with a nose wire
    • Using a mask fitter over a disposable or cloth mask
    • Checking that mask fits snugly with no gaps
    • Adding layers of material (three or more)
    • Knotting and tucking ear loops
  • Masks should consist of two layers. This includes cloth masks for personal use, medical-grade masks used at work and N95 respirators used for high-risk patient interactions. Cloth masks are not medical grade, but multi-layer cloth masks — or a cloth mask layered over a surgical mask — are appropriate for when you are out in public, such as at the grocery store.
  • Don’t double mask with medical-grade, N95 masks. Because medical-grade masks already contain multiple layers of barrier, wearing two masks is not recommended, nor has it been shown to provide additional protection against the virus. Double-masking complicates the doffing process and creates increased risk for exposure if not removed correctly. Double-masking also can cause any medical mask (surgical/isolation or N95) underneath to become dislocated from its safe position or damp as a result of a tighter fit to the mouth.

Handle your mask properly


To put on your mask

  • First wash your hands before picking it up by the ear loops or ties.
  • The mask must cover your nose and mouth at all times.
  • Avoid touching the outside of the mask with your hands. Do not adjust it throughout the day or pull it down to talk.

To take off the mask, repeat the process

  • Clean your hands first and unfasten the ties or ear loops.
  • Do not touch the front of the mask.
  • Wash your hands again after handling the mask.

Learn more about how to wear and care for masks »

Washing your masks

  • Wash cloth masks before first use and after every subsequent use. The navy blue WUSM-provided masks should be hand-washed.

Preventing eyeglass fogging

graphic of hands washing eyeglasses with soap and water

It’s a common problem: Wearing a face mask can make your eyeglasses fog up. Here’s some advice to help avoid that problem. The tips come from two doctors and are published in the journal Annals of the Royal College of Surgeons of England.