Eastern U.S. Is Shrouded in Smoke From Canadian Wildfires and Saharan Dust

Weather|Eastern U.S. Is Shrouded in Smoke and Dust

Wildfire smoke from Canada and plumes of desert dust from the Sahara are smothering large portions of the United States, creating hazy skies and hazardous air quality from the Northeast to the Southeast.

The National Weather Service issued air quality alerts on Wednesday for New York City and many surrounding areas, including New Jersey and most of Connecticut. Officials said that those more sensitive to air pollution should limit going outdoors and watch for respiratory symptoms from 11 a.m. to 11 p.m.

Air quality in the New York City metro area and the Lower Hudson Valley was forecast to be “unhealthy for sensitive groups,” according to the New York State Department of Environmental Conservation. The department had air quality health advisories in effect for these areas, especially for at-risk individuals. The general public, it said, was less likely to be affected.

The U.S. Environmental Protection Agency warns that wildfire smoke contains dangerous pollutants in the form of fine particles known as PM 2.5 that can penetrate deep into the lungs and enter the bloodstream. Short-term exposure can lead to bronchitis, worsen asthma and create other health issues.

The smoke, carried south from fires in Canada, passed over the Midwest on Tuesday. Air quality alerts remained in effect on Wednesday morning across Minnesota, Iowa, Wisconsin, Michigan and Ohio.

Marc Chenard, a meteorologist at the Weather Prediction Center, said that satellite imagery shows a broad swath of smoke still covering the eastern United States on Wednesday. The smoke stretches from northern Georgia to New England and into parts of the Upper Midwest.

“A lot of it is aloft, but there’s still some getting down to the surface,” Mr. Chenard said.

Air quality readings in cities including Minneapolis, St. Paul and Columbus, Ohio, were at “very unhealthy” levels, between 100 and 140, early Wednesday morning, according to The New York Times air quality tracker. The index’s scale runs from 0 to 500; the higher the number, the more polluted the air.

Those levels were an improvement from Tuesday when both St. Paul and Minneapolis had registered readings of 226 in the morning. Above 200, the air is considered “very unhealthy,” and risky for everyone.

While the North deals with smoke, a large plume of Saharan dust crossed the Atlantic Ocean and was expected to spread over Gulf Coast states through Thursday. Mr. Chenard said the dust had already reached parts of Florida by Wednesday morning, and was expected to intensify.

“The highest concentrations of the dust is definitely going to be through today and tonight,” he said on Wednesday. “But there will be some at least lower concentrations that linger over Florida, probably into the weekend.”