Imposing a stricter measure to control the spread of the coronavirus, Gov. Andrew M. Cuomo said on Wednesday that he would start requiring people in New York to wear masks or face coverings in public whenever social distancing was not possible.

The order will take effect on Friday and will apply to people who are unable to keep six feet away from others in public settings, such as on a bus or subway, on a crowded sidewalk or inside a grocery store.

“Stopping the spread is everything,” Mr. Cuomo said during his daily briefing in Albany. “How can you not wear a mask when you’re going to come close to a person?”

The new requirements are bound to make face coverings an inescapable and perhaps jarring sight in New York City for the foreseeable future. They could also introduce a level of mutual obligation and civic duty about wearing masks in public that is more firmly established in Asia than in the West.