To Mask or Not to Mask
Even though Covid-19 restrictions have lifted in most jurisdictions across Canada, debate continues over mask wearing with a wide range of opinions. Masks currently worn by the public vary significantly from homemade cotton models to N95 medical-grade products, which are now available at mass retailers. This article reflects the current science as of January, 2022.
Unlike the cold and flu that is frequently spread by contact, Covid-19 is mostly transmitted by inhaling respiratory droplets carrying the virus. When someone infected exhales, coughs, sneezes, sings, or talks, micron-scale particles go into the air and can be inhaled by others in the space around the emitter. We know that Omicron and the latest sub variant BA.2 are highly transmissible through the air resulting in millions of cases around the globe.
The efficacy of masks in controlling Covid-19 is clear. Both surgical masks and unvented KN95 (and N95) medical-grade masks reduce outward particle emission by 74%-90% during speaking and coughing compared to not wearing a mask . However, the evidence related to homemade cotton-fabric masks is mixed. In fact, a study carried out at the Department of Chemical Engineering, University of California Davis suggested that wearing a cloth mask can actually increase the number of particles released because they are held in the fabric and then emitted due to jaw movement through “particle shedding” . The same study also suggested that this may be due to people speaking louder through their masks and therefore forcing more particles through the material.
However, other studies referenced by the Centers for Disease Control and Prevention in the US have shown that cloth masks did reduce the emission of larger particles and are effective in controlling Covid -19 transmission. The information on the Centre for Disease Control website also supports the science that KN95, N95 and surgical masks are superior .
Now in our sixth wave, it is estimated that about 50% of Covid-19 transmissions are from people who are unaware they are infectious. They are either asymptomatic or pre-symptomatic. The research confirms that wearing a mask of any kind will lower the risk of transmission; KN95, N95 and surgical masks are more effective. Mask wearing is strongly recommended around people that are immunocompromised, including older adults.
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, Sima Asadi, Christopher Capp, Santiago Barreda et. laThe Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities. Nature Research. www.nature.com/scientificreports
 Centers For Disease Control and Prevention Types of Masks and Respirators. Updated January, 2022. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/types-of-masks.html