Unlike conventional dust meters, which count particles, a piezobalance dust meter like the 3521 or 3522 “weighs” mass concentration of particulates. As an air sample enters the system, it travels through the impactor, which captures and removes larger particulates away from the sample. Smaller particulates become electrically charged and deposited on the piezo-crystal. The total mass of the deposited particulates affects the piezo-crystal’s frequency. Since the change in frequency is proportional to the mass of the particulates, the actual weight of the particulates is obtained.