The collection efficiencies of paper-coated glass cylinders at low values of the particle inertial parameter relevant to chemical operations were determined in a wind tunnel under laminar and controlled turbulent flow conditions. Impaction efficiencies computed by the inertial impaction theory for inertial parameters approaching the theoretical cutoff value accurately predict the collection efficiency of cylinders under laminar flow conditions and levels of turbulence less than 7.4. Manyfold increases in the collection efficiency of cylinders at low inertial parameter values were observed as a function of relative turbulence intensity and Eulerian longitudinal macroscale of the turbulent flow field. The collection efficiency data for cylinders can be properly ordered by the Taylor parameter. The leeward deposition efficiency was substantial and exceeded the windward collection efficiency for most flow circumstances.