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The airflow and particle-velocity patterns in the vicinity of a curved, porous sampling surface constituting the inlet of an aerosol sampler, have been determined by Laser-Doppler Velocimetry. The tests were performed on a personal aerosol sampler with a concave sampling surface, referred to as the “button” sampler. Measurements with the button sampler were conducted in a low-speed, open-circuit, horizontal wind tunnel using two types of monodisperse aerosols: 2 μm essentially inertialess propylene glycol particles (their trajectories represent the flow streamlines) and 44 μm inertial fly ash particles. The tests were performed at two free stream velocities (0.5 and 4 m/s) and two sampler orientations (facing the wind and facing downward at 90° to the wind). The sampling flow rate was 2 L/min. Sampling through the curved surface was conducted while the button sampler was freely suspended in the flow or while it was attached to a vertical stagnation plate simulating the human torso. The results in...