As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STRONG ODOR AND IRRITATING FUMES IN COCKPIT AT FL370. DECLARED EMERGENCY, O2 MASK ON, RETURNED TO CVG . LT RECIRCULATION FAN INOP, MESSAGE CAME ON DURING DESCENT. FOUND LT RECIRCULATION FAN INOP UPON ARRIVAL. PULLED AND COLLARED LT RECIRCULATION FAN C/B ON P-36 PANEL. INSPECTED LT RECIRCULATION FAN, FOUND NO FIRE DAMAGE IN DISTRIBUTION AREA. FWD TO MCO AND PLC PER MEL 21-25-01A.