Question: “I wanted to know about the "official" rules of whether we are entitled to wear masks (N95) in class if we feel more comfortable to do so? Most of the professors let me wear a mask in class, but for one of them, he asked me to remove it. I wanted to know if a professor has the right to ask me to remove it, and if not, to which "official" rules I can point them to.”
Facebook post by Professor Danny Quah
Now and then I hear speculation that people are being told not to wear masks because (whispering) "there won't be enough to go around". Since masks don't last forever, demand for them over time is unbounded: no finite supply will ever "be enough to around". Instead, common sense and good personal hygiene will go a long way to protect yourself as well as those around you.
Over the years, the evidence that has accumulated, from literature meta-surveys and from practice in the field, suggests that good hygiene — wash your hands vigorously; apply sanitisers — are highly effective against the spread of respiratory viruses. Certainly, surgical masks have a role to play but unless you're in a situation of focused contact, their efficacy can only be imperfect and will deteriorate, from social engineering factors as much as inappropriate usage.
Breathing through masks is uncomfortable, and without proper care, masks don't seal perfectly and you are likely to remove them improperly. Used over a period of time, masks get contaminated, so unless you keep replacing them, you could be getting a concentrated hit of piled-up bacteria that, otherwise, might dissipate harmlessly. What your mouth and nose emit eventually cover the inside of your mask: that attracts bacteria... and, when you think about it for a second, is actually pretty disgusting.
Of course, if someone around you is coughing and sneezing, do ask them to wear a mask. Someone wearing a mask is to protect you from them, not them from you. So, if you are coughing and sneezing, please do put on a mask: You tell the world you care about their well-being, but except in specific circumstances, it's not to protect yourself.
NUS Dean of Students Leong Ching updated yesterday evening on our colleague Prof KK Phoon's description of the ALARP Principle, i.e., "As Low As Reasonably Practicable". In every situation of risk, weigh up costs and benefits: act when the ratio between them is out of the realm of ordinary experience. Balancing out costs and benefits, drawing on rational thinking and a firm evidence base, has got to be always the right approach.
Jefferson, T. et al. 2011. Physical interventions to interrupt or reduce the spread of respiratory viruses. Cochrane Library (July) doi:10.1002/14651858.CD006207.pub4
Rosenthal, Elisabeth. 2020. How to Avoid the Coronavirus? Wash Your Hands. New York Times (28 Jan) https://www.nytimes.com/…/…/coronavirus-prevention-tips.html