High volume samplers used to measure respirable suspended particulate (RSP) or total suspended particulate (TSP) have some limitations. Passive deposition and re-entrainment can occur, collecting dust before and after sampling or material entering the inlet being blown back into the sample flow. Recirculation can also happen when exhaust from the blower motor enters the sample air, biasing results, but it can be minimized through proper sealing and ducting. Additionally, gases may be absorbed on the filter along with particles, leading to further positive biases in measurements.