This study uses computational fluid dynamics to investigate particle aspiration at the low air velocities typical of occupational settings. A realistic representation of a human head on a simpler geometric torso was positioned facing the wind (0.2, 0.4 m s(-1)), and breathing was simulated using constant inhalation (1.8, 4.3 m s(-1)). Aspiration was simulated using laminar transport for particles 0.3-116 mu m. Results from the 0.4 m s(-1) freestream and 4.3 m s(-1) inhalation rate compared well with results from the literature for smaller particles. For particles >= 68 mu m, simulations yielded smaller aspiration efficiencies than reported in experiments. For all low velocity conditions studied, the aspiration efficiency curve dropped well below the 50% recommended by the ACGIH in the forward-facing orientation. Additional investigation of aspiration efficiency at other orientations relative to the wind is recommended to fully investigate aspiration efficiency for large particles in occupational environments. (c) 2005 Elsevier Ltd. All rights reserved.