COVID-19 (Coronavirus Disease 2019), a highly contagious disease, has caused a pandemic for the whole world. SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) is the main culprit of this disease and it is transferring from human to human with respiratory secretions, which are generated by expiratory activities (e.g., breathing, speaking, laughing, coughing, and sneezing). The transmission of COVID-19 occurs when the virus-bearing respiratory secretions expelled from an infected individual reach the eyes, nose, or mouth of a susceptible individual [1,2]. It has been reported that SARS-CoV-2 can transfer directly through person-to-person contact such as handshaking and hugging, indirectly through contact with fomites (objects or materials that carry infection) such as paper tissue and doorknob, and also via airborne route without any physical contact [3]. The transmission of COVID-19 can be lessened using face masks. Surgical masks are being used by many people in the current pandemic situation. However, do they provide adequate protection against COVID-19?

According to the World Health Organization (WHO), for patient protection, surgical masks are sufficient for health-care staff to wear when they work in the operating room, perforate body cavities, and give care for immuno-compromised patients; WHO also states that patients with airborne infections must wear surgical masks when they are outside the isolation room [4]. In the case of COVID-19, the research findings of Leung et al. [5] suggest that surgical masks can reduce the onward transmission of coronaviruses through respiratory secretions from symptomatic individuals. It implies that surgical masks can control the spreading of COVID-19 from an infected person as they create a physical barrier between the mouth and nose and the surrounding environment. However, it should be kept in mind that they are not designed to block very small airborne particles [6]. Therefore, they may not be effective to stop the penetration of airborne coronaviruses. An experimental study showed that, for surgical masks, the penetration of small virus particles less than 80 nm in diameter can be more than 10% at a lower inhalation rate of 30 L/min whereas it can be above 20% at a higher inhalation rate of 85 L/min [7]. Moreover, surgical masks could allow the virus particles to enter the respiratory system because they loose fit with the face [6]. All these suggest that surgical masks may not give adequate protection for health-care professionals when they are looking after COVID-19 patients. Indeed, surgical masks are not intended to protect the wearer from the environment rather they are designed to protect the environment from the wearer [7].

In fine, surgical masks are not effective in preventing virus particles during inhalation. The nano-size coronavirus could easily penetrate surgical masks. Therefore, relying on surgical masks strategically will not be enough to prevent coronaviruses from entering the respiratory tract. It can be used for symptomatic COVID-19 patients to lessen the spread of viruses through respiratory secretions during exhalation but not for controlling the inward transmission of SARS-CoV-2.

List of References

[1] Mount Sinai Hospital. FAQ: Methods of Disease Transmission. Department of Microbiology, Mount Sinai Hospital: Toronto, Ontario, Canada. Retrieved on March 31, 2020. Available online: https://eportal.mountsinai.ca/Microbiology/faq/transmission.shtml.
[2] World Health Organization (WHO). Pass the Message: Five Steps to Kicking out Coronavirus. WHO: Geneva, Switzerland; March 23, 2020. Retrieved on March 24, 2020. Available online: https://www.who.int/news-room/detail/23-03-2020-pass-the-message-five-steps-to-kicking-out-coronavirus.
[3] Asadi, S.; Bouvier, N.; Wexler, A.S.; Ristenpart, W.D. The coronavirus pandemic and aerosols: Does COVID-19 transmit via expiratory particles? Aerosol Science and Technology 2020, 54(6), 635-638.
[4] World Health Organization (WHO). Prevention of Hospital-Acquired Infections: A Practical Guide; Second Edition, WHO/CDS/CSR/EPH/2002.12; Ducel, G., Fabry, J., Nicolle, L., Eds.; WHO: Geneva, Switzerland, 2002. Retrieved on March 26, 2020. Available online: https://www.who.int/csr/resources/publications/whocdscsreph200212.pdf.
[5] Leung , N.H.L.; Chu, D.K.W.; Shiu, E.Y.C.; Chan, K.-H.; McDevitt, J.J.; Hau, B.J.P.; Yen , H.-L.; Li, Y.; Ip, D.K.M.; Peiris, J.S.M.; Seto, W.-H.; Leung, G.M.; Milton, D.K.; Cowling , B.J. Respiratory virus shedding in exhaled breath and efficacy of face masks. Nature Medicine 2020, 26, 676-680.
[6] FDA (Food and Drug Administration). N95 Respirators and Surgical Masks (Face Masks). U.S. Food and Drug Administration: Maryland, USA. Retrieved on March 28, 2020. Available online: https://www.fda.gov/medical-devices/personal-protective-equipment-infection-control/n95-respirators-and-surgical-masks-face-masks#s2.
[7] Bałazy, N.; Toivola, M.; Adhikari, A.; Sivasubramani, S.K.; Reponen, T.; Grinshpun, S.A. Do N95 respirators provide 95% protection level against airborne viruses, and how adequate are surgical masks? American Journal of Infection Control 2006, 34(2), 51-57.

Md. Safiuddin, Ph.D., P.Eng.
Professor
George Brown College, Casa Loma Campus
146 Kendal Avenue, C Building, Room C303
Toronto, Ontario, Canada M5T 2T9
Adjunct Professor, Department of Civil Engineering
Ryerson University, Toronto, Ontario, Canada M5B 2K3
College Website: https://www.georgebrown.ca/facultybios/Md.-Safiuddin.aspx
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