Fulwood Royal Mail sorting office chemical alert
More than 100 workers were quarantined for four hours after a chemical alert at a Royal Mail office in Preston.
Emergency services were called to Pittman Way, Fulwood, at 16:00 BST after reports that an unknown substance had been detected in a loading bay.
About 120 workers were evacuated to the car park where they were held until 20:00 BST.
Lancashire Fire and Rescue Service said the building was reopened after no hazardous substances were found.
A fire service spokesman said: "The workers were held as a precaution as if there had been a substance we would need to contain the hazard on site."
A mobile fire station and hazardous material unit was set up at the site and a Merseyside Fire Service Detection and Identification Monitoring unit was also called in.