(NEW YORK) — 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 more than 19.5 million acres across Canada so far this year, with no end in sight. There are nearly 500 active wildfires throughout the country and over 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 more than a month.
Here’s how the news is developing. All times Eastern:
Jun 29, 11:36 AM EDT
Pittsburgh air quality reaches ‘very unhealthy’
The Air Quality Index in Pittsburgh climbed to 220 Thursday morning, which falls under the “very unhealthy” category.
Any number over 100 is considered unhealthy for sensitive groups.
Pittsburgh Mayor Ed Gainey is encouraging residents to stay inside on Thursday.
Jun 29, 8:03 AM EDT
Wildfire smoke forecast to dissipate by the weekend
The Canadian wildfire smoke drifting into the United States is expected to largely dissipate by the weekend.
By Friday morning, the smoke is forecast to linger in the eastern Great Lakes from Detroit to Ohio, Pennsylvania, western New York state, down to Virginia and the Carolinas.
New York City is not expected to see much smoke, but skies over the Big Apple could still be a bit hazy due to the nearby plumes.
By Friday evening, the smoke will really begin to diminish in the East with lingering effects from New York to the Carolinas.
Jun 29, 5:20 AM EDT
Videos show Canadian wildfire smoke casting haze over US cities
Videos verified by ABC News show smoke from Canada’s wildfires casting a haze over several U.S. cities on Wednesday.
One video, taken by a driver and posted on Twitter, shows the wildfire smoke hanging over a highway near Lawrenceburg, Indiana, as the state and much of the Midwest were under air quality alerts.
Lawrenceburg is located some 100 miles southeast of Indianapolis, near the state border with Ohio and Kentucky. The city is about 25 miles west of Cincinnati, Ohio.
-ABC News’ Matthew Holroyd
Jun 28, 6:05 PM EDT
Over 100 million Americans under air quality alerts
Air quality alerts remain in effect for more than 100 million Americans across the Midwest and into the Northeast Wednesday evening, as wildfire smoke from neighboring Canada blankets large swaths of the United States.
Air quality alerts remain in effect for more than 100 million Americans across the…Read More
Hard-hit Chicago, Detroit and Minneapolis remain among the top five places in the world with the worst air quality as of Wednesday evening.
The air quality alerts are mainly for people in sensitive groups who have upper respiratory issues.
Near-surface smoke is expected to stretch from Wisconsin to Kentucky and into t…Read More
The near-surface smoke is expected to stretch from Wisconsin to Kentucky and into the Carolinas Wednesday evening. Some of the smoke will likely make its way into the mid-Atlantic overnight. Pittsburgh to Syracuse are forecast to see hazy, smoky skies and poor air quality Wednesday night.
Through Thursday, the smoke is expected to move out of the Midwest and linger farther east but not be as heavy. No significant smoke issues are forecast at this time for major Northeast cities, including New York City.
-ABC News’ Melissa Griffin
Jun 28, 1:10 PM EDT
Air quality health advisory issued in New York
While the poor air quality is mostly hovering over the Midwest, the dangerous smoke is also drifting toward the East Coast.
New York Gov. Kathy Hochul has expanded Wednesday’s air quality health advisory to include the entire state.
“Air in Western New York, Central New York, and the Eastern Lake Ontario regions is forecast to be ‘Unhealthy,'” Hochul’s office said. “The forecast for the remainder of the state, including New York City and Long Island, is ‘Unhealthy for Sensitive Groups.'”
Jun 28, 12:39 PM EDT
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.”
Jun 28, 12:30 PM EDT
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
Jun 28, 8:59 AM EDT
Where the 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.
Jun 28, 7:59 AM EDT
What to know about the Air Quality Index from wildfire smoke and how it affects human health
Heavy blankets of smoke billowing over the United States from wildfires burning in neighboring Canada are threatening the health of millions of people — even non-vulnerable populations with no preexisting conditions. But what about the smoke makes it so hazardous for humans to be around?
Wildfire smoke contains fine particulate matter, known as PM2.5, which are microscopic solid or liquid droplets — often 30 times smaller than the diameter of a human hair — that can be inhaled and cause serious health problems, according to the U.S. Environmental Protection Agency.
Most particles form in the atmosphere as a result of complex reactions of chemicals, such as sulfur dioxide and nitrogen oxides — pollutants emitted from power plants, industries and automobiles. But wildfires likely contain PM2.5 that is up to 10 times more harmful than the same type of air pollution coming from combustion activity, according to a 2021 study conducted in California.
PM2.5 is considered unhealthy for “Code Orange” and sensitive groups once the Air Quality Index surpasses 100, according to AirNow, a website that publishes air quality data. Once the AQI surpasses 150, it is considered “Code Red,” unhealthy for some members of the general public who may experience health effects, with sensitive groups experiencing more severe effects.
The AQI is at “Code Purple” once it surpasses 200, considered “very unhealthy” with increased health risk for all populations. “Code Maroon” is labeled as “hazardous” and a health warning for emergency conditions once the AQI reaches 300 and higher.
At Code Maroon, “everyone is more likely to be affected,” according to AirNow.
A “good” AQI is measured at 50 and below, and a “moderate” air quality index ranks between 51 and 100.
-ABC News’ Julia Jacobo
Jun 28, 7:45 AM EDT
Chicago air quality hits ‘very unhealthy’ category
As Canadian wildfire smoke infiltrates the midwestern United States, the air in Chicago has deteriorated to the Air Quality Index’s> “very unhealthy” category.
The AQI in hazy Chicago reached 250 on Tuesday afternoon. Any number over 100 is considered unhealthy for sensitive groups.
“We recommend children, teens, seniors, people with heart or lung disease, and individuals who are pregnant avoid strenuous activities and limit their time outdoors,” Chicago Mayor Brandon Johnson warned in a statement. “For additional precautions, all Chicagoans may also consider wearing masks, limiting their outdoor exposure, moving activities indoors, running air purifiers, and closing windows.”
The smoke is forecast to clear on Friday when showers and thunderstorms hit the region.
Earlier this month, the AQI in the northeastern U.S. reached near maximum with levels in the high 400s.
Jun 28, 7:03 AM EDT
20 US states under air quality alerts
As of Wednesday morning, 20 U.S. states are under air quality alerts from Minnesota down to Georgia and as far north as western New York.
Wildfire smoke from neighbouring Canada is currently blanketing large swaths of the United States, from Iowa to western Pennsylvania to North Carolina and most everywhere in between. Only Chicago is getting a small reprieve on Wednesday morning due to a lake breeze, which isn’t expected to last for long.
Later on Wednesday, the smoke is expected to cover areas from Minnesota to Washington, D.C. and down to the Carolinas.
By early Thursday morning, the smoke will be seen in Minneapolis, Chicago, Indianapolis, Atlanta and Pittsburgh. But by the afternoon, it will linger from Detroit to Atlanta and east to Washington, D.C. and Philadelphia.
New York City could be impacted as well, but most of the smoke from the Canadian wildfires is expected to stay in western New York state, Pennsylvania and southern New Jersey.
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