Electronic air cleaners use an electrical field to trap charged particles.  Like mechanical filters, they may be installed in central heating and/or air conditioning system ducts or may be portable units with fans.  Electronic air cleaners are usually electrostatic precipitators or charged-media filters.

In electrostatic precipitators, particles are collected on a series of flat plates.  In charged-media filter devices, which are less common, the particles are collected on the fibers in a filter.  In most electrostatic precipitators and some charged-media filters, the particles are deliberately ionized (charged) before the collection process, resulting in higher collection efficiency.