Dozens of people needed treatment after a hazardous material believed to be pepper spray was spread through the air conditioning system at a German airport.
Hundreds of other passengers had to be evacuated and more than a dozen flights were cancelled at Hamburg airport.
An airport spokesman said that police and firefighters had concluded from their initial investigation the substance was probably pepper spray.
Authorities are working to determine how it got into the airport's air conditioning.
The 68 injured people - both passengers and staff members - complained about breathing problems, burning eyes and nausea.
All outgoing and inbound flights were halted for about an hour due to the evacuation and unknown health hazard. A total of 14 flights were cancelled and several planes were diverted. Air traffic delays continued throughout the afternoon.
Evacuees who were uninjured had to wait outside in freezing temperatures.
Firefighters designated special areas outside the airport building where doctors examined people with physical symptoms of exposure.