To mask or not to mask— That is the question

To Mask or Not to Mask

To mask or not to mask— That is the question

Los Angeles Mayor Eric Garcetti has mandated that workers in essential businesses wear face coverings due to the coronavirus pandemic. He also instructed businesses to refuse service to customers who aren’t wearing them. So is there data to support this mandate? Actually, there is.

A study published online last week in Nature Medicine* demonstrated that the use of surgical masks inhibit the spread of respiratory viruses found in aerosolized droplets.

To quote the authors,“Our results indicate that aerosol transmission is a potential mode of transmission for coronaviruses as well as influenza viruses and rhinoviruses.”

The full scope of the study is beyond this blog, but to summarize: this randomized, controlled study (NOT anecdotal!) confirmed that coronavirus is spread, not only by person-to-person contact, but also prolonged exposure in the air. The use of masks decreased the rate of transmission.

So what do you do if you pass someone on the trail who isn’t wearing a mask?  The researchers also noted that the amount of virus aerosolized was time dependent. They stated, “Given that each exhaled breath collection was conducted for 30min, this might imply that prolonged close contact would be required for transmission to occur.”  In other words, unless you are in prolonged close contact with someone coughing or singing, you are probably  safe. What to do if you’re in the store and someone is coughing and you forgot your mask? Maintain your 6 feet safety zone.

*Respiratory virus shedding in exhaled breath and efficacy of face masks

Nancy H. L. Leung, Daniel K. W. Chu, Eunice Y. C. Shiu1, Kwok-Hung Chan, James J. McDevitt, Benien J. P. Hau, Hui-Ling Yen, Yuguo Li, Dennis K. M. Ip, J. S. Malik Peiris, Wing-Hong Seto  ? Gabriel M. Leung , Donald K. Milton and Benjamin J. Cowling