Eight workers at Stobhill Depot in Gorebridge, Midlothian, were checked over by ambulance crews after they came in contact with a bag containing an unknown, strong smelling substance.
An investigation by specialists found the chemical was ammonia chloride sulphate and posed a low to medium risk, similar to a cleaning product.
A spokeswoman for Midlothian Council, said: “We take these types of incidents very seriously and as soon as they occur we work with our colleagues in emergency services to put our emergency contingency plan into place.
“We would like to thank everyone for their patience this morning while the fire service undertook their investigations. Thankfully the chemical turned out to be low risk with no health implications for anyone involved.”