Bronchopulmonary disease in the workplace. Challenge testing with occupational agents.

Inhalation challenge tests may be indicated in the investigation of occupational asthma and hypersensitivity pneumonitis when a worker's history is unconvincing or the precise etiologic agent is unclear. Challenge exposures may be conducted in either the workplace or the laboratory, and surveillance should extend for 24 hours unless the probability of late responses is negligible.