06:54 AM EDT, 09/25/2025 (MT Newswires) -- Delta Air Lines ( DAL ) is replacing auxiliary power units, or APUs, on over 300 of its Airbus A320 jets to combat toxic fume incidents that have affected passengers and crew, The Wall Street Journal reported late Wednesday, citing a Delta spokesman and internal documents.

The airline is nearly finished with the APU upgrades, which started in 2022 as part of an effort to address the recent surge in fume events, which have reportedly led to brain injuries and other illnesses.

The APU, which generates electricity and supplies air to the cockpit and cabin, can leak toxic fumes even when not in use, the Journal reported, citing maintenance specialists.

Airbus has identified the APU as a major cause of the fume incidents in the A320 family, with oil leaks in the engine or power unit's compression chamber vaporizing neurotoxins, the WSJ reported.

Delta operates 310 A320 aircraft, including 76 of the latest models, and the APU replacement is expected to reduce but not eliminate the risk of toxic leaks, the report said.

Delta did not immediately respond to MT Newswires' request for comment.

(Market Chatter news is derived from conversations with market professionals globally. This information is believed to be from reliable sources but may include rumor and speculation. Accuracy is not guaranteed.)