As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED SMOKE/HAZE IN THE CABIN AT 500FT ON TAKEOFF. THE AIRCRAFT RETURNED TO LGA AND LANDED WITHOUT INCIDENT. MAINTENANCE RAN BOTH ENGINES WITH PACKS AND BLEEDS ON AND WERE NOT ABLE TO DUPLICATE THE FAULT. THE AIRCRAFT HAD BEEN DE-ICED PRIOR TO DEPARTURE.