Objective: To compare inflammation and lung function in swine workers after periods with and without respiratory protection during work. Methods: Twenty-three workers were examined before and after two non-protected work shifts. One shift was preceded by a period with diminished exposure by use of respirators. The other shift was preceded by an unprotected period of work. Results: Endotoxin concentrations were similarly high (24,636 and 28,775 endotoxin units/m(3)). A 3.1% cross-shift decline in forced vital capacity occurred after the period with respiratory protection (P 0.01). Blood leukocytes increased more (P = 0.01) and bactericidal/permeability-increasing protein was reduced (P = 0.015) only after the period with respiratory protection. Plasma interleukin-6 increased (P < 0.0001) during both visits. Conclusion: Respiratory protection resulted in cross-shift inflammatory and respiratory reactions at return to unprotected work.