Air Quality Poor As Wildfire Smoke Clings To Northeast, Great Lakes

Note: Y​ou can track the real-time air quality for your area using The Weather Channel air quality tracker at this link.

Unhealthy air quality continues to plague parts of the Great Lakes and Northeast from thick wildfire smoke that was sent southward into those regions from Canada.

H​ere's where the worst air quality is right now. Unhealthy air - code red on the EPA's air quality index - was blanketing much of the interior Northeast except for New England, and lingered in parts of the Great Lakes as of Friday morning, as the data in map below from airnow.gov shows.

T​hat includes Cleveland; Detroit; Milwaukee; Pittsburgh; Syracuse, New York; and Washington, D.C.

M​eanwhile, areas that were impacted by thunderstorms in the lower Ohio Valley and mid-Mississippi Valley have seen much improved air quality, including Indianapolis, Cincinnati, Louisville and St. Louis.

H​ere's the latest smoke forecast. Gradual air quality improvement is expected Friday in the Midwest areas still experiencing smoke.

In the Northeast, slowly-improving air quality is expected during the day, Friday, over Maryland, Virginia and West Virginia.

Unfortunately, from Pennsylvania and New Jersey north into New York state and a few parts of western New England, smoke may persist into much of Friday, but lessen by Saturday.

How to know w​hat air quality levels are bad. Air quality levels can top 300, but anything over 100 can start causing issues for people more at risk, like those with asthma or lung disease, children and the elderly.

Air quality levels over 150 can start causing problems even for healthy people.

L​evels over 200 are considered "very unhealthy" and start exacerbating health issues in all people.

O​nce levels top 300 they are considered "hazardous" to everyone.

The smoke can trigger serious health problems. T​his smoke is particularly bad for you and can cause coughing, shortness of breath, increased heart rate and other immediate effects, even in healthy people. It can also aggravate chronic heart and lung conditions, increase the risk of stroke and heart attack, damage vital organs and shorten a person’s lifespan.

It may be necessary to stay indoors with windows and doors closed and avoid outdoor activities in areas with the worst air quality.

Follow these helpful tips to stay safe amid the pollution.

A​ir quality has ranked among some of the worst on record since Tuesday. I​mages of a smoke-filled Chicago skyline filled up social media as residents woke up Tuesday morning, and IQAir's live rankings had Chicago as the major city with the worst air quality worldwide. Minneapolis and Detroit also ranked unusually high due to the wildfire smoke filling the air across the region.

(​MORE: Air Pollution May Increase Risk Of Dementia, Analysis Finds)

S​o far, particulate pollution levels (PM2.5) set new record highs for any calendar day in 10 major cities,​ including Chicago, Cleveland and Pittsburgh, according to data from the U.S. EPA. Milwaukee had at least code red air quality for four consecutive days through Friday.

"Tuesday would normally be a perfect summer day of weather here in the western Great Lakes. Weak high pressure, low humidity and highs near 80 degrees," said weather.com senior meteorologist Jon Erdman, who lives in southern Wisconsin. "Instead, I couldn't see a hint of blue sky outside my front door Tuesday morning, and the smoke smell is as strong as I can recall from other Canada smoke episodes in recent years."

Low pressure funneled the smoke into the Great Lakes, Ohio Valley. The counterclockwise flow around a low-pressure system pushed the surface-based smoke southward into the Great Lakes from Canada's Quebec province amid what has been the country's worst year for wildfires since record-keeping began.

A similar setup filled the New York City skyline and much of the Northeast with smoke earlier this month.

T​hunderstorms washed the air clean in parts of the Midwest. A pair of thunderstorm clusters, one of which was a derecho, cleared the air of wildfire smoke in parts of the mid-Mississippi and lower Ohio Valleys on Thursday.

A​mong the cities that had much cleaner air after thunderstorms included Cincinnati, Indianapolis, Louisville and St. Louis.

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