Miners from five sodium-chloride (7647145) mines were investigated for reduced pulmonary function, increased pulmonary symptoms, and presence of respirable particles following nitrogen-dioxide (10102440) (NO2) exposure, Salt, blue collar, potash, and above ground coal populations were used as comparisons. Maximum forced expiratory volume (FEV), maximum forced vital capacity (FVC), and peak flow were measured and flow at 50 and 75 percent of expired FVC (FEF50 and FEF75) were derived from a maximum envelope curve. Respirable particulate and NO2 samples were collected. Ten females and 249 males exposed to NO2 concentrations of 31 to 387 parts per million for 36 to 428 months and 20 to 122 milligrams per cubic meter for 27 to 122 months to particulates were examined. The overall prevalence of cough, phlegm, and dyspnea was 24, 28 and 7 percent, respectively. Cough was statistically associated with age and smoking but not with any of the other exposure variables. Phlegm was statistically associated with age, smoking, years of exposure, cumulative particulate exposure, and NO2 exposures. Dyspnea was associated with shortness of breath and age but not with any of the other exposure parameters. The workers with symptoms showed reduced FEV and FVC as compared to workers without symptoms. The FEF50 pattern was inconsistent and showed no trend for reduction with increase in severity of symptoms. After adjustment of age and smoking the study population showed no increased prevalence of cough, phlegm, dyspnea, or obstruction (FEV/FVC less than 0.7) as compared to underground salt, potash, blue collar, above ground coal miners, and other workers. The underground coal population consistently had elevated obstruction (younger miners) and phlegm (older miners) as compared to other workers. The mean predicted pulmonary function in these workers was reduced 2 to 4 percent for FEV and FVC, 7 to 13 percent for FEF50, and 18 to 22 percent for FEF75 in comparison to all populations. The authors conclude that NO2 exposure does not cause the observed pulmonary changes.