HELSINKI, Dec. 1 (Xinhua) -- Part of terminal two at Helsinki Airport was evacuated after 24 airport employees suffered from minor breathing symptoms on Thursday, Finnish national broadcaster Yle reported.
All the employees were reported to have mild symptoms of breathing difficulties, as well as throat and eye irritations and nine of them were sent to hospital for treatment.
Heini Harve-Rytsala, a physician at Peijas Hospital where the nine people were hospitalized, told Yle they had very mild symptoms.
A better-equipped unit of Finland's defense forces was called in to investigate after the rescue workers failed to find what had cause the incident, according to Yle.
Police have ruled out the possibility of the incident being a criminal offence. They believe the incident was most likely caused by a malfunction of the air-conditioning system.
The part of the airport which was evacuated at Helsinki Airport was reopened in the evening.