There is a tremendous amount of disinformation circulating regarding the use of masks to decrease transmission of COVID-19. As with many aspects of the pandemic, mask use has become politicized which is unfortunate when it comes to public health. All science, including public health science, is messy. Recommendations change as evidence becomes available. A new virus with limited data, such as the coronavirus causing COVID-19, adds to the uncertainty.
Initially there was a significant shortage of masks for frontline workers, which was why authorities were reluctant to recommend mask wearing to the general public. It is understandable that people may look back at this old advice and not know what to believe. I think we should trust the public health scientists and realize their recommendations may change as better data becomes available. It took years to fully understand transmission of HIV. People who disregarded emerging recommendations for safe practices in the early days of HIV did not fare as well as those who took precautions to protect themselves and their loved ones.
What We Do Know
The coronavirus is primarily transmitted person to person via respiratory spray. Staying away from people (social distancing) and decreasing the germs being transmitted between people are both ways to decrease the spread of the virus. While high quality research regarding mask use is limited, all of the data supports mask wearing as a key public health measure to decrease viral spread.
Are Masks 100% Effective?
The gold standard N-95 mask is 95% effective at keeping the wearer free of inhaling viral particles. These masks are still best reserved for front-line workers in high risk settings where aerosols of viral particles occur. Surgical masks are less effective and cloth face coverings even less so in protecting the wearer. However even a 50% reduction in viral transmission is statistically important.
For the general public, the reason for wearing a facial covering is to help protect others from you when you cough, sneeze or even talk and spray viral droplets into the air. Many people who become infected can unknowingly spread the COVID-19 virus because they have few or no symptoms. So wearing a mask is showing respect for others and is your way of helping lessen the spread of the disease. It is important that the mask not be so thick as to make breathing through them completely uncomfortable. Filter inserts are probably not necessary and may make the masks more uncomfortable.
Do Masks Cause Low Oxygen Levels?
Absolutely not. We wear masks all day long in the hospital. The masks are designed to be breathed through and there is no evidence that low oxygen levels occur. There is some evidence, however, that prolonged use of N-95 masks in patients with preexisting lung disease could cause some build-up of carbon dioxide levels in the body. People with preexisting lung problems should discuss mask wearing concerns with their health care providers. There is absolutely no scientific evidence that mask wearing or physical distancing weakens the immune system.
So What Should You Do?
Decreasing the severity of the pandemic is about statistics. If you desire 100% avoidance of infection, the only way to achieve it is to isolate yourself completely. That is not practical or mentally helpful for the vast majority of people. The next steps are to do things which limit the likelihood of spread from person to person. These include distancing and mask wearing.
The further away you are from an infected patient, the less likely you are to get the virus. Six feet is better than two feet and 12 feet is probably better than six. At some point the distance away becomes statistically meaningless. Unfortunately, there is no absolute correct number. Airflow (indoor, outdoor, ventilation, wind, etc), temperature, humidity, the viral load being produced by the infected person and the susceptibility of the uninfected person all play a role in how far apart you need to be.
Masks are not 100% effective, but mask wearing does decrease the risk of viral spread. Public health professionals believe that mask wearing and social distancing are the keys to controlling the first wave and diminishing or avoiding subsequent waves of the virus. Mask wearing allows us to open the economy up faster. Not wearing a mask around others only worsens the pandemic, leads to more disease, and worsens the economic effects.