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Electrostatic effects are the cause of two important but opposite phenomena in filtration, especially of gases. In the filtration of dusts from gases, it is possible for electrostatic charges to build up on the filter media. Should these reach a high enough
level then a spark discharge could occur, and, if the dust mixture is explosive, a consequent explosion could result in serious damage to the filtration system. This risk can be minimized by making the filter medium conductive and then ensuring that its mounting connects it safely to earth. A conductive medium will have carbon fibres or metallic filaments embedded in it.

The opposite phenomenon makes effective use of the charges that almost all dust particles carry (and which can transfer to the filter medium to be the source of the charges described as hazardous in the previous paragraph). If the filter medium can be given the opposite charge to that carried by the dust particles, then the attraction of the electrical forces will cause the dust to separate more efficiently onto the filter medium. One way of doing this is to use fibres that are electrets (made from dialectric materials that carry a quasi-permanent electric charge or have a dipole polarization), or filter media carrying an excess charge (created, for example, by a corona discharge). Polypropylene or fluropolymers are suitable materials for this purpose. Electrically assisted filtration of this form is widely employed in air cleaning, especially for respiration.

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