Why, and How, We Should Wear Masks To Protect Against COVID

July 14, 2020

Dr. Bill Burman Headshot
“One of the most important ways to control the COVID-19 pandemic is right in front of us – a mask (or, more generally, a face covering). There is increasingly strong evidence that universal masking is effective in decreasing the risk of transmitting COVID to someone else. The primary way that COVID is transmitted is through droplets that are expelled from the nose and mouth, especially when coughing, sneezing, talking, and singing.  

Most of these droplets fall to the floor before they travel more than 2 meters (hence, the recommendation to stay 6 feet of physical distancing, when possible). Masks markedly decrease the amount of droplets that are expelled and the distance they travel. Universal masking is particularly important for COVID because it is clear that transmission occurs from persons who are feeling fine and is an important component of overall spread. Finally, droplets can stay in the air much longer in an indoor air space then they do outside.  

The controversy about masking seems to be melting away as the COVID pandemic continues and accelerates in many parts of the country. Denver County was a leader, and now many cities, counties, and states are now requiring masks in indoor public spaces. That is the science.  

What are the practical issues about the strategy of universal masking?

  • It is most important when inside and when talking (or singing!).
  • The general rule for in-person gatherings or meetings during the COVID pandemic is “fewer, smaller, shorter, and outside (when possible)”.
  • The default when in a public indoor space is to mask. The risk of transmission is much less if there is at least 6 feet of distancing, assuming there is reasonable air movement.
  • It isn’t easy to be understood when talking through a mask, but that is the time that it is most important to do so – talking generates droplet particles. One of the largest known super-spreader events in the COVID pandemic happened among a choir rehearsing in a relatively small room – more than 80% of the choir was infected. So, if you are having trouble being understood while masked, find another way to have the conversation (have a phone call, use Zoom, etc.), but don’t take your mask down for in-person conversations
  • It is fine to lower the mask when eating, but be very attentive to keeping distance when doing so.
  • The air movement makes masking much less important when outside. I don’t wear a mask when biking or walking outside on my way to the office. I do put my mask on before I step inside a building, and if I am in a crowded outdoor space. It is fine for kids to play outside without masks if they are keeping a reasonable distance.

 - Bill Burman, MD, Executive Director of Denver Public Health