What was found
AIRCRAFT WAS GROUNDED: SMOKE / FUME EVENT, APPROX 30MIN AFTER TAKEOFF CABIN ADVISED OF UNDETERMINED CHEMICAL FUMES / ODOR. ACCOMPLISHED SMOKE, FIRE, FUMES ITEMS TO INCLUDE UPPER, LOWER RECIRC FANS OFF, IFE OFF AND WAITED 15 MIN ODOR /FUMES DID NOT DISSIPATE. CABIN CREW EXPERIENCED DIZZINEESS, EYE AND THROAT IRRITATION, LIGHT HEADNESS. MADE DECISION TO AIR INTERRUPT AND RETURN TO LANDING IN EZE FOR INSPECTION. EMERGENCY WAS DECLARED AND LANDED OVERWEIGHT WITHOUT ISSUE. MAINTENANCE FOUND FWD ZONAL DRYER IN,OPERATIVE,MMSG 21-71211 OP TEST SHOWS FAN FAILED. MAINTENANCE REPLACED ZONAL DRYER FAN.