As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SUSPECTED SMOKE IN CABIN AROUND SEAT 9D. EMERGENCY DECLARED. (FLT 5480) CLOSED THE SMOKE WAS ACTUALLY COMING FROM THE LOWER AIR CONDITIONING VENT, RAN BOTH PACKS WITH APU AND ENGINES INDIVIDUALLY NO SMOKE EVIDENT IAW AMM. MX CHECKED THE PACKS OIL SYSTEM ALL WAS NORMAL. ALL A/C SYSTEM OPS CHECKED GOOD.