Specialist fire crews were summoned to a disused car park in Hattersley on Wednesday after potentially dangerous chemicals were discovered inside a car.
Police also responded to the reports at around 9.45am that the abandoned vehicle, parked on Chain Bar Lane, contained potentially harmful substances.
A cordon was in place for much of the day as the specialist crews, wearing protective clothing, carried out tests and assessed whether the chemicals were dangerous or not.
A tactical aid unit was also at the scene throughout the day.
A spokesperson for Greater Manchester Fire and Rescue Service said: "We were called at 9.45am to Chain Bar Lane, off Stockport Road, to reports of a vehicle containing barrels of chemicals.
“Fire crews were on the scene whilst the substances are being tested."