(CNN) — More than 80 million people from the Midwest to the East Coast of the United States are on air quality alert as smoke from Canadian wildfires crosses the US border on Tuesday, causing beach closures, warnings of reduced visibility and calls to stay indoors.

Canada is experiencing its worst fire season on record with hundreds of wildfires across the country, more than 200 of which are burning “out of control”, according to Canada’s Interagency Wildfire Center. Forest fires have generated the highest emissions recorded in the country, according to a report published on Tuesday by copernicusa division of the space program of the European Union.

As smoke enters the United States, air quality alerts have been issued for the states of Iowa, Wisconsin, Illinois, Indiana, Michigan, Delaware and Maryland, as well as parts of Kansas, Missouri, Minnesota, Ohio, Pennsylvania, New York and Virginia, according to the US National Weather Service. Residents are encouraged to stay indoors with the air conditioning on or, in some areas, to wear N95 masks if they must be outdoors.

As of Wednesday, many locations from Pennsylvania to Iowa are experiencing very unhealthy air quality (Level 5 of 6), with a small Danger Zone (Level 6 of 6) east and north of Detroit , Michigan, according to AirNow.gov.

Chicago, Detroit, Indianapolis, Cleveland, Pittsburgh, Milwaukee and Davenport in Iowa all had air quality readings in the very unhealthy range this morning.

Unhealthy air quality levels (Level 4 of 6) from smoke extend as far south as St. Louis, Missouri; Louisville, Kentucky and Cincinnati, Ohio.

A code red — which is unhealthy air quality — was issued Wednesday for much of the Midwest and the Ohio Valley, according to AirNow.gov.

Localities under Code Red include Pittsburgh and Eire in Pennsylvania, Columbus in Ohio, Indianapolis and Fort Wayne in Indiana, Madison and Milwaukee in Wisconsin, and Chicago. Many of these places are already experiencing unhealthy to very unhealthy air quality.

Chicago and Detroit had the world’s worst air quality for hours on Tuesday night, with Detroit’s air at one point reaching a “very unhealthy” air quality index of 205, according to IQAir. Chicago recorded an air quality index of 174 on Tuesday night.

City skylines could be seen shrouded in smoke on Tuesday, with white haze lingering over roads and neighborhoods.

“I can feel like a burn in my throat,” said Dalya Khuder, who was visiting Detroit. LXYZ, a CNN affiliate. “The air quality is really bad and I don’t want that in my lungs.”

The City of Chicago urges all residents, especially those with heart or lung conditions, the elderly, pregnant women and young children, to avoid outdoor activities and protect themselves from exposure. Chicago public schools and camps are also moving activities indoors, city officials said in a news release.

About 11 miles away, Evanston, Ill., will close all swimming beaches and cancel a concert on Tuesday due to poor air quality, the city posted on Facebook, asking residents to limit swimming. outdoor exhibition until Wednesday.

Across the Michigan border, the Mackinac Bridge was covered in smoke on Tuesday. Drivers were advised to drive slowly and carefully due to reduced visibility on the bridge.

High levels of fine particulate matter in Michigan’s air could make it unhealthy or dangerous for all residents in some locations, not just sensitive groups, the state’s health department has warned.

“The most protective option when the air is unhealthy for you is to stay indoors with air conditioning, reduce strenuous activities and limit outdoor activities. If you must be outdoors, N95 masks provide enhanced protection when used according to product directions,” the Michigan Department of Health and Human Services said.

Smoke from wildfires carries particulate matter, or PM2.5, a tiny but dangerous pollutant that, when inhaled, can penetrate deep into lung tissue and enter the bloodstream, according to the Centers for Disease Control and Prevention. This particle has been linked to a number of health issues, such as asthma, heart disease and other respiratory diseases.

US cities subject to air quality alerts are mostly in “code-orange“, with the tune considered unhealthy for sensitive groups, or “code red“, that is, when the air is considered unhealthy for the general public.

The Mackinac Bridge, which connects Michigan’s Upper and Lower Peninsulas, is covered in smoke from the Canadian fires. (Credit: Mackinac Bridge Authority)

New York may see smoke cloudy skies again

New York is also expected to see harmful levels of smoke this Wednesday and Thursday in some areas, about three weeks after New York City topped the list of worst air pollution as smoke from Canadian wildfires s is high towards the south, turning the sky orange.

“New Yorkers should be prepared for elevated levels of fine particulate pollution from smoke this Wednesday and Thursday,” Governor Kathy Hochul said in a statement. “Current projections show that the highest concentrations of smoke will slowly move east through the eastern half of New York State on Thursday, spreading across much of the state.”

Additionally, the New York City Department of Health has warned of deteriorating air quality.

As for this Wednesday, they say that “they currently expect the air quality index (AQI) to be in the moderate range (between 51 and 100)”, but they warn that “the wind pattern may change quickly without notice”.

In a statement, they stress that children, the elderly and people with respiratory problems should take precautions if the levels reach between 101 and 150.

“When the AQI exceeds 150, ALL New Yorkers should begin taking precautions,” they say, including limiting time outdoors, taking a mask to prepare, among other precautions.

In Ohio, meanwhile, a spokesperson for the Cleveland mayor’s office said “what happened in New York a few weeks ago and today in Chicago could happen here in Cleveland tomorrow. “.

The Ohio Northeast Region Coordinating Agency issued an air quality advisory, predicting fine particulate levels in the ‘unhealthy’ air quality index range .

Indianapolis drivers were also warned of reduced visibility, with the National Weather Service saying to “be prepared for haze that could suddenly reduce visibility” in some areas Tuesday and Wednesday.