Electrostatic precipitators (ESPs) are the devices where particles present in dirty air are charged electrically to form a corona of negative charges around them. These charged dust particles when passed over collection plates of ESPs (electrically connected earth) loose their charge and settle down. If ESP in a thermal power plant is unable to generate high voltage of several thousands, that means it is not functioning properly. Due to this, the dust particles will not be able to get charged and settle down. This will result in pollution of air.