That's not to say that IAQ equipment isn't crucial for a portion of the population; for example, those who suffer from severe allergies or asthma definitely see its benefits on a daily basis. For others, though, ultraviolet (UV) lights, HEPA filters, and humidifiers are often viewed as nice accessories to have if they can afford them after replacing their furnaces or air conditioners.
That attitude can make it a difficult sell for contractors; however, many manufacturers are doing their best to educate homeowners about the consequences of indoor pollutants through extensive advertising on TV, radio, and in magazines.