For more than a month now, many Mainers have been staying home as much as possible. We’re doing it not because the risk is high that any one individual will catch COVID-19 on any one trip. We’re doing it because collectively limiting person-to-person contact is the best way we have now – along with frequent hand-washing – to starve the coronavirus and slow its spread.

Now we should add masks to that list as well.

Early on in the outbreak, most official guidance in the U.S. said wearing a mask was not necessary. However, that was based on a misunderstanding about the coronavirus, as well as a desire to save scarce surgical masks and the more advanced N95 respirators for health care workers.

Now, cloth masks are widely available, and easy to make by anyone with a T-shirt. People can easily get one, and it’s clear they can do a lot to lower infection rates.

It’s likely most people are infected either by breathing in viral droplets that have been released into the air by an infected person, or by touching a surface that has the virus on it and then touching their own face.

Masks can limit both the amount of virus-laden droplets that are released into the air by an infected person and how widely the droplets are disseminated. Research has shown they do both much better than covering up a sneeze or cough with a hand or elbow.

That makes it imperative that everyone who may have the coronavirus wear a mask in most public spaces, particularly where social distancing is difficult. And because symptoms don’t show in an infected person for at least five days and as many as 14, and may not show at all in many cases, the best course is for all individuals to act as if they may have it.

By no means do masks make you impervious to the virus. They are not a license to go and do as you please, unconcerned that you’ll be infected or infect others. However, used together with hand-washing and physical distancing, masks dramatically lower the chance of infection.

But they have to be used together to really work; hand-washing, for instance, can take care of any infected droplets that may escape a mask.

And the efficacy of masks, physical distancing and personal hygiene all depends on widespread use. The percentage of the population that is infected may be low, but we all have to be vigilant, since we don’t have enough testing to determine who has it and who doesn’t, and many people may be asymptomatic.

Portland and Brunswick officials have voted to require masks for workers who interact with the public. Gov. Mills on Tuesday said there will be a statewide requirement to wear masks in some public places, with more details coming soon.

In any case, orders can be ignored. But we have hope that most people will do the right thing.

Mainers began physical distancing before official stay-at-home orders because they understood it was necessary to help themselves and others. It should be the same with masks. This should be a question of civic duty and pride.

Wearing a mask protects other people from the wearer, not the other way around. Even more than physical distancing, it’s about doing something for someone else, someone you don’t know and may never even see.

At the cost of a little discomfort, we can all do something for the greater good – again.