An apparatus and method for sampling semivolatile compounds is disclosed. A collection bag is placed around an air conditioning vent on an aircraft. An opening in the collection bag receives air from the air conditioning vent into the bag. An exit in the collection bag allows the air sample to escape from the collection bag. Vacuum applied by tubing at the exit pulls the air sample from the bag. Flow is adjusted so that the inflow into the collection bag exceeds the outtake, thereby inflating the bag. The inflation of the collection bag assures that the air being sampled is only air originating from the air conditioning vent.