Passengers on a British Airways flight from Barcelona to London were met by ambulances on the tarmac at Heathrow Airport on Sunday after travelers reported feeling unwell due to fumes in the cabin.
“The safety of our customers and crew is always our top priority. This aircraft landed normally at Heathrow following reports of a technical issue,” British Airways said in a statement. “Customers disembarked the aircraft safely via steps, and we’ve apologized to them for the delay and inconvenience caused to their journey.
The flight was British Airways 475, operated by a an Airbus A320.
Social media posts show travelers standing around with emergency vehicles and British Airways shuttle buses at the airport.
Fume incidents are not unheard-of in aviation, though they are rare and can sometimes be a health hazard.
Travelers, and especially flight crews, can experience long-term adverse health impacts if certain toxins are released into the cabin, though the substances involved in the British Airways incident were not ultimately found to be hazardous.
Advocates in the U.S. and abroad are pushing for tighter standards around aircraft cabin air quality, and are encouraging the installation of monitoring equipment on commercial aircraft. Currently, no such standards or requirements exist in the U.S.
This article originally appeared on USA Today.