Some six passengers were hurt when the unknown gas was released at the German airport, forcing check-in desks to shut down as a precaution.
The travellers were sprayed by an irritant at around 11am on Monday, near the check-in desks at Terminal 1.
Firefighters rushed to the scene after receiving reports of people suffering from eye irritation and breathing problems.
Airport police tweeted saying it was released by an “unknown person” and investigations were ongoing.
After the gas was sprayed, two automated desks closed and passengers are thought to have been evacuated from the immediate area.
Police later said no one was seriously injured, and gave the incident the “all clear”.
Fears grew of a potential bomb threat when a taxi driver alerted police to a 37-year-old man acting suspiciously during his cab ride.
Police met the suspect at the airport, who confessed he was carrying explosives in his luggage.
In response Terminal A was quickly evacuated, and the entrance to the rail station was closed as a precaution.
The man was arrested, but after searching his bags the authorities found computer parts and small bottle of fuel used for camping, but nothing which could make a bomb.
The man was later identified as having mental health problems, and was known to authorities.
He was taken to a psychiatric ward.