Officials at BWI Thurgood Marshall Airport shut down two concourses for about an hour Monday morning, while investigators tried to determine the nature and source of an unusual odor. All checkpoints reopened by 10 a.m., after investigators removed what they believe was a can of pepper spray from a trash bin.

Investigators discovered the item, which they are still processing, discarded in a trash can near the security check point at Concourse B. A passenger may have tossed the aerosol can before going through security, officials said.

Southwest Airlines and Air Tran both held flights to accommodate passengers, officials said, adding the incident had only a limited impact on schedules.

Several people had reported a strong, irritating odor in Concourse B about 8 a.m., prompting officials to evacuate passengers and employees from that area as well as Concourse A as a precaution, officials said.

Mary.gail.hare@baltsun.com

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