Wildfire smoke updates: CDC issues health alert on wildfire smoke exposure
The smoke is forecast to dissipate over the weekend.
Millions of Americans are on alert for unhealthy air quality as smoke from wildfires in neighboring Canada drifts to the United States.
Wildfires have burned a record of 20 million acres across Canada so far this year, with no end in sight. There are currently 500 active wildfires throughout the country and more than 250 have been deemed out of control, according to the Canadian Interagency Forest Fire Center. The smoke has been making its way to the U.S. for over a month.
Latest headlines:
Chicago's Air Quality Alert in effect until Wednesday night
In Chicago, where the Air Quality Index is in the "very unhealthy" category, an Air Quality Alert is in effect until Wednesday night.
Chicago Mayor Brandon Johnson is urging "particularly sensitive populations, including individuals with heart or lung disease, older adults, pregnant people, and young children" to avoid outdoor activities.
Camps have been moved indoors where possible, the mayor said, and he's encouraging "Chicagoans without access to properly ventilated and safe indoor conditions" to "please utilize our public libraries, senior centers, Park District facilities, and the Cultural Center or the six community service centers that operate from 9am-5pm."
White House monitoring air quality issues as Biden visits Chicago
President Joe Biden has touched down in Chicago for fundraising and an economic address, and the White House said his schedule has not been modified due to the poor air quality in the city.
"No modifications to today's schedule that I'm aware of as a result of this," principal deputy press secretary Olivia Dalton said. "But certainly, we are monitoring the air quality issues across the country closely and federal agencies are ensuring that federal resources are available in affected regions as appropriate."
The Air Quality Index in hazy Chicago reached 207 on Wednesday morning. Any number over 100 is considered unhealthy for sensitive groups.
-ABC News' Molly Nagle
How to stay safe from wildfire smoke amid reduced air quality
Wildfire smoke and ash can irritate eyes, nose, throat and lungs, making you cough or wheeze and can make it hard to breathe, according to the U.S. Centers for Disease Control and Prevention.
The CDC says the most effective way to protect yourself during wildfire emergencies is to stay indoors or limit time outdoors when there is smoke in the air. This is especially important for those with heart or lung conditions who are at higher risk for adverse health effects.
"People who are most at risk are [the] elderly, immunocompromised, young children and people who already have respiratory problems, people with asthma and things like that," said Dr. Stephanie Widmer, a member of ABC News' Medical Unit.
Read more here.
-ABC News' Nadine El-Bawab and Youri Benadjaoud
Where the wildfire smoke is concentrating and why
The latest round of unhealthy air quality due to smoke from wildfires in Canada has pushed into the United States, and it's ability to concentrate over areas from Wisconsin to Kentucky is aided by recent storms that spawned tornadoes, large hail and [damaging winds]).
Winds at the mid-levels of the atmosphere are causing the Canadian wildfire smoke to concentrate over a specific area of the midwestern and eastern U.S.
Meanwhile, a heat dome that’s been causing stagnant deadly heat in the Deep South for weeks is keeping the smoke largely out of the region.
The next round of widespread showers and thunderstorms for this area of the eastern Midwest and the East is forecast to arrive on Friday and continue through the weekend, which will clear the smoke.
But as long as the wildfires continue to rage in Canada, these events of dense smoke plumes will likely continue to disperse into the U.S. Canada's wildfire activity typically peaks from June to August.
23 US states under air quality alerts as wildfire smoke blankets Midwest, rolls into Northeast
As of Thursday morning, 23 U.S. states are under air quality alerts from the Midwest to parts of the South and into the Northeast where wildfire smoke from neighboring Canada is creating hazy skies.
The worst-affected areas are currently from Wisconsin down to Tennessee and up to Virginia and even parts of Pennsylvania.
As the day develops, plumes of smoke are expected to linger over the Great Lakes, the Ohio Valley and into the Appalachian Mountains. Some smoke might even make its way into the Mid-Atlantic and parts of New Jersey.
New York City will be largely spared from the heaviest smoke. An air quality alert was issued there only as a precaution. Most of the day will be sunny with perhaps a touch of haze due to the smoke nearby.