Alaska Airlines has apologized to passengers aboard an Anchorage-bound flight from Barrow Friday after buckets containing fish and formaldehyde leaked in the cargo area of the plane.

When flight 55 landed in Anchorage, crews unloading the plane could smell the chemical and discovered the spill, according to Alaska Airlines spokeswoman Bobby Egan. She said a passenger was transporting the buckets as checked baggage.

Protocols for handling hazardous materials were initiated, Egan said, and involve bringing in a third-party vendor to remove and potentially dispose of the contaminants. Formaldehyde is commonly used as a preserving chemical in mortuaries and laboratories. Short-term exposure may cause watery eyes or burning sensations in the eyes, nose, and throat, as well as coughing, wheezing, nausea and skin irritation, according to the Centers for Disease Control and Prevention.

She said the cargo area is sealed from the main cabin area, so passengers were not at risk of exposure to the chemical.

All but one of the bags in the cargo area were undamaged by the spill and released to their owners after testing was completed over the weekend, according to Egan. The one damaged bag was sent to a third party for additional testing and the airlines is paying to replace its contents, she said.

“We feel awful about this situation, and [are] doing further analysis of this,” she said Monday.

Egan said the airlines has refunded tickets and will issue a $500 travel voucher to all flight 55 passengers for future travel plans.

Egan couldn’t comment on how the buckets were stored or contained for travel. She said any customers hoping to fly with or ship potentially hazardous materials should call ahead to make sure they are following proper shipping procedures before their flight.