The more expensive, higher efficiency filters are more effective, but require more maintenance. These filters remove less than 5 percent of the particulates that pass through them and offer little protection for human lungs. They should be replaced every one to two months to prevent air restriction to your forced-air unit. The average cost of these filters is under a dollar. Electrostatic Panel Filters Electrostatic panel filters use static electricity to filter the air.
Static electricity is created as the air flows through the filter.
Some of these filters contain plastic materials which are charged with positive and negative charges to attract larger particles. These filters remove 10 to 15 percent of the particulates that pass through them, including some larger mold spores and pollen. An extended-surface filter will cost more than a standard panel filter and will last from three months to a year. An electronic air cleaner uses high voltage to charge particles in the airstream. The charged particles collect on an oppositely charged metal plate.