Polycyclic aromatic hydrocarbons (PAHs) are one of the most important and carcinogenic components in diesel exhaust (DE). Therefore, ambient PAHs concentrations were measured and characterized for work areas in a locomotive engine inspection plant. Pre- and post-shift urine samples and concurrent air samples were collected on 17 workers to measure the concentration of urinary 1-hydroxypyrene (1-OHP), a metabolite of pyrene. Increased urinary 1-OHP concentrations were observed over at least three consecutive sampling days. The biological kinetics of pyrene metabolism was studied with a one-compartment pharmokinetic model. The conversion rate and elimination rate of 1-OHP were estimated using nonlinear mixed-effects model, and validated with multiple nonlinear regression models by assessing the pattern of elimination rates of each worker separately. Urinary 1-OHP was confirmed to be a sensitive marker of PAHs exposure with mean half-life of 29 h in this population of Chinese workers. The study results would be beneficial to future occupational and environmental studies of PAH exposure.