Wildfire smoke and air quality updates: Northeast flights disrupted

Washington, D.C., public schools have canceled all outdoor activities, including athletic games, for Wednesday due to the poor air quality.

A "Code RED Air Quality Alert" has been issued for the nation's capital.

New York City public schools also canceled outdoor activities.

"We urge everyone to reduce prolonged or heavy exertion outdoors," NYC Public Schools tweeted.

In Port Washington, New York, on Long Island, the superintendent announced Wednesday that all students will stay inside during physical education and recess.

"This decision is aimed at minimizing exposure to the poor air quality and ensuring a safe learning environment for everyone," the superintendent said.

Most of New England and much of the East Coast were under air quality alerts on Wednesday, with smoke from Canadian wildfires expected to reach as far south as South Carolina.

A new dose of very thick smoke was expected to drift into New York City and Philadelphia by Wednesday afternoon, lasting into the evening.

That smoke is then expected to move south into Washington, D.C., on Wednesday night and into Thursday morning.

Conditions around New York City and in the I-95 corridor could improve Thursday evening, but get worse in western New York, Pennsylvania and West Virginia, as the winds shift.

-ABC News’ Max Golembo

The air quality in New York City worsened Tuesday evening and is expected to "deteriorate further" Wednesday afternoon and evening, New York City Mayor Eric Adams said in a statement.

"At this point, the New York State Department of Environmental Conservation has issued an Air Quality Health Advisory for all five boroughs. While conditions are anticipated to temporarily improve later tonight through tomorrow morning, they are expected to deteriorate further tomorrow afternoon and evening," Adams said.

“Currently, we are taking precautions out of an abundance of caution to protect New Yorkers’ health until we are able to get a better sense of future air quality reports," he said.

Adams said students should still go to school on Wednesday, but New York City public schools won't have outdoor activities.

"These recommendations may change based on updated air quality conditions that come in, but, in the meantime, we recommend all New Yorkers to take the precautions they see fit to protect their health," he added.