Chicago's O'Hare International Airport has reopened its train station after an ammonia leak forced the authorities to shutdown the station for nearly four hours.
The Chicago Transit Authority train station was closed at 9am on 12 June, in response to a strong ammonia smell in the area.
The Blue Line trains between the airport and Rosemont were suspended and shuttle buses were deployed in both directions between the two locations.
The station platform was evacuated, while the Chicago Fire Department ordered hazmat crews to determine the source of the odour.
The crew conducted extensive checks of water, sewers and other parts of the facility.
It was determined that the strong ammonia smell came from cleaning products that were used by the workers in an airport parking garage above the station.
After the leak was secured and cleaned up, normal services resumed at the airport train station by the afternoon, although shuttle buses continued operations until 1pm and the CTA announced that minor delays could continue.
No individuals were harmed as a result of this incident.