As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT#8400, BNA-BOS. (AIRCRAFT PERFORMED AN AIR TURNBACK TO BNA) STRONG CHEMICAL ODOR ON TOFF.O2 MASKS DONNED; COMPLIED WITH INFORMATION NOTICE 2017-T015,SECTION B1.IDENTIFIED ODOR AT BOTH PACKS.DECONTAMINATION LEVEL A WAS ACCOMPLISHED PER TSM 05-50-00.AIRCRAFT OK FOR SERVICE.