With an electrostatic precipitator, as the collector plates become loaded with dust, the unit loses efficiency quickly. When an electrostatic precipitator loses efficiency, the air resistance doesn't increase any, but the dust, even though it is given an electrical charge, simply passes through the unit and back into the house. An electrostatic precipitator may need to be cleaned as often as every week if very much dust is present, although every month may be a good rule of thumb in most situations. This is done by removing the core containing the collector plates and placing it in a dishwasher, or soaking it in a tub of soapy water. The medium efficiency mechanical filters and HEPA filters can last as long as six months to a year before they need changing.
Electrostatic precipitators have the disadvantage of producing some ozone, a known pollutant.
Most of the oxygen molecules in the air are paired, and this is what we need to breathe. When three oxygen molecules are combined, the compound is called ozone. It is not good to breathe. Ozone is released mainly when the units make their characteristic popping sound. This occurs when electrical arcing occurs inside the unit.