As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5319 EWR-STL - ON INITIAL CLIMB-OUT OF EWR, LAV SMOKE ALARM WENT OFF. THE FLIGHT ATTENDANT STATED, HAZE IN THE CABIN AND SMELLED SMOKE. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO FIELD IN EWR. MAINTENANCE TROUBLESHOT THE SMELL DOWN TO THE NR 1 BLEED SYSTEM AND THE AIRCRAFT WAS FERRIED TO CMH. MAINTENANCE REMOVED AND REPLACED THE NR 1 ENGINE. OPS CHECK AND LEAK CHECK GOOD. NO SMELL NOTED IN CABIN IAW EMB J/C CE720001.