The market for indoor air filtration and purification will reach $7 billion in 2010, up from $5.6 billion, according to “Air Filtration and Purification World Markets,” a study by the McIlvaine Company ( Much of the growth is expected to come from the medium-efficiency segment of the market.

Medium-efficiency filters (F5-9) are a step above spun-glass furnace filters in terms of efficiency, but not as efficient as the micro fiberglass high-efficiency (HEPA) filters. Commercial buildings and residences continue to upgrade to medium-efficiency filters from previously used low efficiency filters. The result is that by 2010 medium-efficiency filters will represent 50 percent of the total market, according to McIlvaine Company. The rest of the market will be shared by high-efficiency filters, low-efficiency filters, electronic filters, and gas-phase filters.

Portable room air units are not included in the forecasts. Electronic units that are included are the whole-house and commercial electronic precipitators, which are used in recirculating air systems.

The U.S. will still be far and away the major purchasing country in 2010, according to the McIlvaine Company.