In “It’s Time to Make Your Own Face Mask” (column, nytimes.com, March 31), Farhad Manjoo clearly shows that face masks function not only as personal protective equipment but also as what we might call “others’ protective equipment” by reducing airborne viral spread from sneezes and coughs. One of the most self-protective and altruistic things we can do now is to wear a face mask while in public because asymptomatic people with Covid-19 can still transmit the illness.

Eileen Kavanagh

Dirk Winter

New York

The writers are psychiatrists at Columbia University Medical Center.

To the Editor:

You may have heard that surgical masks don’t work for preventing viral infections and may increase the risk of infection. Why is this? It is because people not accustomed to wearing masks can’t keep their hands off them. They constantly fiddle with them, adjust them, pull them down to talk and so on. Every time they do this, they are contaminating their mask with their hands, and if their hands have virus or bacteria on them, then they are risking infection.

As a surgeon, I am used to standing around for hours without touching my mask or my face, but it is very difficult for someone who is not used to this. So, if you decide to wear a mask for protection against viral or bacterial infection, here is what you need to do:

(1) Start with a clean mask. If you are reusing a mask, make sure that you keep it clean when you are not wearing it.

(2) Wash your hands well with soap and water, for a minimum of 20 seconds but preferably more.

(3) Place your mask and get it adjusted perfectly. It may help to do this in front of a mirror.