Midair scare forces packed passenger jet into emergency landing, travelers hospitalized

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.

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 Airbus A330-300 carried 13 crew members and 283 customers.

"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.

"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. 

"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.

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.