As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BWI FLT 1853 - ON TAKEOFF FROM PHL, EN ROUTE TO BWI, CREW REPORTED A NAUSEATING SMELL IN THE COCKPIT FROM THE AIR CONDITIONING SYSTEM. SMELL REMAINED DURING FLIGHT AND LANDING. MAINTENANCE OPERATED EACH PACK FOR 30 MINUTES AND DETECTED A STALE ODOR FROM THE AIR VENTS IN THE COCKPIT. REMOVED AND REPLACED LEFT AND RIGHT COALESCER BAGS PER MM 21-51-41. GROUND OPERATED PACKS OFF APU. NO ODORS NOTED.