Two fire engines, two fire rescue units and over 20 firefighters and officers were called to investigate reports of a chemical smell at a disused science lab in Inskip Drive, Hornchurch earlier this afternoon.
A safety cordon was set up and 150 people were evacuated from the area as a precaution.
The Brigade was called at 1329 and the incident was over for firefighters at 1656. Crews from Hornchurch and Dagenham attended the scene.
There are no reports of injuries.