The New York City health department raised its COVID-19 alert level to high from medium on Tuesday, and said it now advises all New Yorkers to wear a mask in indoor public settings. “People who are older than 65 or otherwise at a high risk of severe illness from COVID-19 should also wear a mask in crowded outdoor settings and avoid gatherings when possible,” according to a statement from the NYC Health Commissioner. The move comes a day after the department cautioned that cases were approaching the threshold that would bump the alert to high. The high alert means there is high community spread and substantial pressure on the health care system. If things deteriorate, the city would move to very high, at which point health care systems would be determined to be overwhelmed. New York City is currently averaging 4,000 COVID cases a day, according to a New York Times tracker, up 51% from two weeks ago.