An anonymous reader writes: A chlorine gas leak at an Apple data center in North Carolina has hospitalized five workers. The Catawba emergency services received an alert call at 2pm local time from the Apple site based on Startown Road in Maiden. Footage was captured at the scene of the building being evacuated, people being treated by medical crews and supplied with oxygen masks. Initially authorities said that there had been two unidentified chemicals involved in the leak, later confirming that it had been chlorine gas. When cooled chlorine can be stored as a liquid, but turns to gas if exposed to air. If breathed in by humans the chemical can be damaging to the respiratory system, dissolving the mucous membrane causing fluid to build up in the lungs which can lead to suffocation by drowning. An investigation has revealed that the noxious chemical leak was given off from on-site water-cooling equipment used to cool the center's servers. The five injured workers were treated at the nearby Catawba Valley Medical Center and were all discharged shortly after. Neither the medical center nor Apple have provided further details on the incident.