Approaches to assessing pulmonary dysfunction and susceptibility in workers.

Indices of the maximal forced expiration are the most widely adopted method of screening for occupational lung disease because of their ease of measurement, employee acceptability, and reproducibility. However, these indices may lack sensitivity, specificity, or validity in detecting cases of some occupational lung diseases at asymptomatic stages when intervention may affect outcome. In populations at increased risk for occupational asthma, pneumoconiosis, or hypersensitivity pneumonitis, three other types of screening are being evaluated in field settings: tests for bronchial hyperreactivity, barriers to diffusion, and abnormalities in gas distribution in the lung. The potential methods of screening--cold air challenge, methacholine challenge, peak flow logs, diffusing capacity, and single breath nitrogen tests--await clinical trials in industrial settings to evaluate whether early case finding of susceptible subjects can result in prevention of morbidity.