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.
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.
Read more here.
-ABC News’ Julia Jacobo
