During his press conference today, Gov. Cuomo of New York announced he was issuing an executive order requiring everyone in the state to where a protective covering or mask over their mouth and nose when in public.

“If you’re going to be in public and you cannot maintain social distancing then have a mask,” Cuomo said. He continued, “And put the mask on when you are not in socially distant places. You’re walking down the street, you’re walking down the street alone, great. You’re now at an intersection and there are people in the intersection and you’re going to be in proximity to other people, put the mask on.

“That is by executive order. So if you’re going to get on public transit, you’re going to get on a bus, you’re going to get on a subway, you’re going to stand on a subway platform, you’re going to walk in a neighborhood that is busy, you’re going to be on a sidewalk, you’re going to pass other people on a sidewalk, you’re not going to be able to maintain social distancing, you must wear a mask.”

Cuomo said he was allowing three days for people to comply with the new order. This is quite a change from what many experts were telling us about masks just a couple months ago.

On Feb. 27 the CDC Director Robert Redfield gave an interview where he said:

Houlahan: Should you wear a mask if you are healthy?

Redfield: No.

Redfield also told Congress there was no role for masks in the community:

“There is no role for these masks in the community,” he old the House Foreign Affairs Committee on Thursday. “These masks need to be prioritized for health care professionals that as part of their job are taking care of individuals.”

This advice persisted for some time, partly because experts were concerned about shortages and medical professionals having to compete with regular people for masks:

The WHO was still recommending only sick people wear masks on March 26:

The problem with all of this advice is that many people get the virus and don’t know they are sick for several days. If they are not wearing a mask during that time, they could be spreading the virus to everyone around them without knowing it. So having everyone to wear a mask or face covering in public should help with this type of accidental transmission.

Also, it’s worth noting that the rule about six feet of separation is really a minimum safe distance. As the NY Times pointed out this week, it’s possible that aerosols created by coughs or sneezes can spread the virus up to 26 feet (if you’re not wearing a mask). Even breathing can probably spread the virus several feet. The Times published a visualization of this yesterday which is worth a look.

Here’s the announcement:

Update: Gotta love Vox.