It is thought that the chemical spread through the airport’s air-conditioning system.
German news agency DPA reported on Sunday that 50 people had complained about breathing problems and burning eyes.
Firefighters examined individuals to determine whether they needed to be taken to hospital. Those who left the airport had to wait outside the terminals in sub-zero temperatures.
All flights were halted for several hours owing to the evacuation, but air traffic resumed at about 2pm local time (1pm GMT), said Karen Stein, an airport spokeswoman.
The cause of the incident was not known, she added. “We’re working closely together with the authorities to find out more,” Stein said.