5.2 Respiratory hygiene |

5.2 Respiratory hygiene

5.2.1 Mask selection

Healthcare workers: surgical masks should be worn when performing sterile procedures, or as general protection against droplets infections. N95 respirators should be worn in the clinical care of patients with confirmed or suspected COVID-19.

Public use (especially for individuals with respiratory symptoms): surgical masks are recommended to people exposed in crowded and poorly ventilated places, such as taking public transports, students in school and individuals visiting clinics or hospitals.
* Hand hygiene should be performed before and after taking off the mask to avoid contamination of our hands. Change masks timely. Replace the mask immediately if it is damaged, wetted or soiled. After taking off the mask, discard it into a lidded waste bin and perform hand hygiene immediately.

*Hand hygiene should be performed before and after taking off the mask to avoid contamination of our hands. Change masks timely. Replace the mask immediately if it is damaged, wetted or soiled. After taking off the mask, discard it into a lidded waste bin and perform hand hygiene immediately.

Surgical Masks or N95 Respirators

5.2.2 Structures and mechanisms of filter materials

Larger particles: captured by filter fibers directly when they impact or intercept the fibers
Smaller particles: constantly bombarded by air molecules, causing them to deviate from the air stream and come into contact with a fiber
Oppositely charged particles: attracted to charged fiber

* All particles that come into contact with a fiber will stay attached to the fiber firmly, thus filters can capture particles smaller than the pore size.

References
Van Doremalen N, Bushmaker T, Morris DH, et al. (2020): Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. New England Journal of Medicine. In press.
He X, Reponen T, McKay R & Grinshpun SA (2014): How Does Breathing Frequency Affect the Performance of an N95 Filtering Facepiece Respirator and a Surgical Mask Against Surrogates of Viral Particles? Journal of Occupational and Environmental Hygiene 11: 178-185
He X, Reponen T, McKay RT & Grinshpun SA (2013): Effect of Particle Size on the Performance of an N95 Filtering Facepiece Respirator and a Surgical Mask at Various Breathing Conditions. Aerosol Science and Technology 47: 1180-1187.
N95 Respirators and Surgical Masks. Available at: https://blogs.cdc.gov/niosh-science-blog/2009/10/14/n95/. Accessed 17 Feb, 2020.