Hamburg Airport had to be evacuated after an unknown toxin spread through its air conditioning system, injuring dozens of people.
According to the German news agency DPA around 50 people, complained about breathing problems and burning eyes.
Some people were taken to hospital, while those who were evacuated had to wait outside in freezing conditions before being let back inside a short time later.
Authorities have been trying to work out what the hazardous substance is after the alert was raised in a security check area.
Police have said it is not a terrorist incident.