Around a dozen people were evacuated following reports of a leak at a supermarket in Bedfont.
A total of 11 people were asked to leave from adjoining shops, as a precaution, said a spokeswoman from the fire service.
She added: "We were called at 2.32pm to a supermarket on Staines Road to reports of a possible leak from a refrigerator.
"It was a refrigerator system in the cold store.
"The incident was over at 4.21pm.
"We did a sweep for chemicals but there were no elevated readings."
A refrigeration engineer was also sent to the scene.
No injuries were reported.