Wildfire smoke that has cast a sickening shroud over major cities in the eastern United States hampered air travel Thursday, creating headaches for major aviation hubs and disrupting plans for thousands of travelers.

The Federal Aviation Administration said Thursday morning that had delayed all flights to New Jersey’s Newark Liberty International Airport across the country. It also suspended departures to Philadelphia International Airport due to low visibility and delayed certain flights to New York’s LaGuardia Airport.

More than 230 flights across the country were delayed and 10 others canceled as of Thursday morning, according to FlightAware.com, a flight tracking service.

FlightAware’s «MiseryMap» showed Hartsfield-Jackson Atlanta International Airport and Newark Liberty International Airport were experiencing the most significant disruptions as of 9 a.m. ET Thursday.

In a statement, the FAA said it «may need to take steps to safely manage traffic flow into New York City, DC, Philadelphia, and Charlotte due to reduced visibility from wildfire smoke.»

The agency said its travel advisories would change as weather conditions evolve throughout the day.

In many major cities along the East Coast on Thursday, the air quality was hazardous. New York City’s air quality was 183 on the air quality index scale, making it the worst in the world, according to IQAir.com, a Swiss monitoring service.

Detroit had the fourth worst air quality in the world at 9:30 am ET, hovering around 121 on the index.

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