These data confirm and extend the previous results of Schwartz et al , Reynolds et al and Senthilselvan et al regarding the longitudinal decline in lung function test variables in exposed workers in swine confinement facilities. Schwartz et al demonstrated a relationship between longitudinal decline in lung function test variables and environmental contaminants. Reynolds et al demonstrated a dose-response relationship between longitudinal decline and environmental exposures. Senthilselvan et al demonstrated that the workers in swine confinement facilities suffered an excess yearly decline in FEV1 and FVC of 26.1 and 33.5 mL/year, respectively, over men who lived in rural areas but did not experience farming or other potentially detrimental occupational or environmental contaminant inhalation exposures. Thus, it seems relatively well established that swine confinement workers suffer yearly reductions in lung function test variables that are in excess of those observed in nonexposed, nonfarming control subjects. Both previous smoking status (exsmoking) and concentrations of ambient air contaminants are potential determinants in annual decline in both FEV1 and FVC, while age is an important predictor of annual loss in FEV1; shift change at baseline evaluation is the predictor of the annual rate change in both FEV1 and FVC that emerges as the most powerful in both models.