A Boston-bound Delta Air Lines flight was forced to make an emergency landing in Portugal, disrupting travel plans for more than 280 passengers.
The flight on Sunday from Barcelona, Spain, to Boston, Massachusetts, was diverted to Porto after smoke was detected in the cabin.
Agence France-Presse (AFP) reported that 14 passengers required medical attention after the plane landed, citing Portugal's civil protection service.
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Of the 14 passengers, four were taken to local hospitals for smoke inhalation and were reportedly only "lightly" affected, the news agency said.
A Delta spokesperson confirmed the Sept. 27 incident to Fox News Digital but did not comment on the hospitalization reports.
The diversion was due to a "reported mechanical issue," the official said.
"The flight landed safely, and we apologize to our customers for the delay in their travels as we work to get them to Boston as safely and quickly as possible," the spokesperson added.
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Delta Air Lines said it was working to rebook customers on alternative flights to their final destinations.
The Airbus A330-300 carried 13 crew members and 283 customers.
The air in aircraft cabins "is as good as or better than the air found in offices and homes," according to the Federal Aviation Administration (FAA).
"In rare instances, mechanical issues such as failures of an engine oil seal or recirculation fan bearings can cause fumes to enter the cabin," the FAA notes on its website.
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"Airlines are required to report these incidents to the FAA. The FAA investigates the causes and makes sure they’re fixed before the aircraft returns to service."
All airlines are required "to supply clean air to both passengers and crew members," the FAA added.
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"Airplanes must be designed to provide the equivalent of 0.55 pounds of fresh air per minute per occupant, a ventilation rate that is consistent with other public environments," the agency's website states.
Other flights have made headlines in recent months after unexpected incidents prompted crews to return to airports or alter their routes.
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Earlier this year, a Cape Air flight bound for Boston was forced to return to Nantucket, Massachusetts, shortly after takeoff when the upper section of its main cabin door partially opened mid-flight.
More recently, a Delta Air Lines flight bound for Orlando returned to Minneapolis-St. Paul International Airport minutes after takeoff due to a reported medical issue involving a pilot.
The Aug. 31 flight, which carried 178 passengers and seven crew members, landed safely before Delta arranged for a new crew to continue the trip to Orlando.