Abstract: A portable air sampler to measure the concentration of a chemical compound in the air, especially in a workplace, measures the quantity of the chemical in its gas phase and in its particle phase. The sampler is connected to a pump which draws ambient air through an inlet tube and out a nozzle. A housing holds a filter aligned with the nozzle. The air is immediately separated into two parts, one portion continues straight through the filter, the second turns 180.degree.. The particles, due to their mass and resulting inertia, will travel in the forward direction to be collected in the filter. The portion of air that flows through the filter continues through a sorbent tube where the vapor (gas phase) from this portion is collected. This sorbent tube also collects the quantity of the chemical that evaporates from the particles collected on the filter.