B737 CREW DETECTS SMOKE DURING APCH AND DECLARED AN EMER.

Narrative

20 MILES ON FINAL AND CONFIGURED GEAR AND FLAPS 15 FOR ATC SPD REQUEST OF 170 KTS. I SMELLED AN ODOR AND THOUGHT IT MIGHT BE POLLUTION FROM OUTSIDE THE ACFT. I MADE A COMMENT TO THE CAPT AND ALMOST IMMEDIATELY THE 'A' FLT ATTENDANT CALLED ON INTERPHONE TO SAY SHE SMELLED SMOKE IN THE CABIN AND THOUGHT SHE SAW SMOKE. BOTH PLTS DONNED O2 AND 100%. CAPT SAID TO DECLARE AN EMER AND HE SPED UP TO ARR IN ZZZ A LITTLE SOONER. I TALKED TO THE 'A' FLT ATTENDANT ON INTERPHONE TO ASK IF IT WAS WORSE AND WHAT THE CONDITION WAS. SHE SAID THEY COULD SMELL SOMETHING AND WERE SEARCHING FOR THE ORIGIN; I TOLD HER WE WOULD BE ON THE GND IN 5 MIN. ATC OFFERED EITHER RUNWAY. WE LANDED; TOOK THE HIGH SPD; AND EMERGENCY VEHICLES WERE EVERYWHERE. THE FIRE CHIEF CAME UP ON GND AND TOLD THE CAPT THEY ALREADY SCANNED THE ACFT WITH INFRARED FROM THEIR TRUCK AND FOUND NO HOTSPOTS AND SUGGESTED WE PROCEED TO THE GATE. THE FLT ATTENDANT HAD ALREADY CONFIRMED; ON THE GND; THAT THE ODOR WAS DISSIPATING. THE CAPT DECIDED TO PROCEED TO THE GATE. THE FIRE DEPARTMENT (FD) WAS READY AND WAITING IN THE JETWAY. NORMAL PAX OFFLOAD AFTER CLRNC FROM FD. ACFT TURNED OVER TO MAINT. NOT SURE WHAT COULD BE DONE TO PREVENT THIS. CREW COORDINATION WAS PARAMOUNT WITH GOOD COMMUNICATION COMING FROM THE FLT ATTENDANT; ATC; AS WELL AT THE FLT DECK CREW.