As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK/DECLARED EMERGENCY. FLIGHT ATTENDANTS REPORTED STRONG "SMOKY ACID" TYPE SMELL IN CABIN, WORSE IN AFT CABIN. SUBSIDED WHEN GASPER AND RECIRC FANS TURNED OFF, SMELL CONTINUED IN CABIN, NO VISIBLE. WILL REPLACED GASPER FAN PER MM.