Electronic air cleaners remove particles by electrostatic forces similar to electrostatic precipitators used in industrial gas cleaning. There are three basic designs: the ionizing plate type, the charged-media non-ionizing type, and the charged-media ionizing type. Operation of electronic air cleaners is based on the principle that particles moving in air stream can be charged and then subsequently collected on plates of opposite charge. An electronic air cleaner draws particle-laden air past a serious of ionizing wires that produce positive ions; this air then passes through channels between a serious of negatively charged collection plates, which attract the positively charged particles. These air cleaners are more efficient than a conventional mechanical filter. They are able to capture small particulate, including pollen and cigarette smoke particles.