Ironically, the issues and concerns about poor indoor air quality surfaced sometime after the smokers were sent outside or were isolated from the mainstream. We survived those melancholy years only to face a growing and hostile public who are wondering why they are feeling ill and becoming sick at work.

In 1968 filtration served one important role: Protect the HVAC coil fans and motors until the next coil cleaning and the inevitable duct cleaning. Coils were washed twice a year, filters were replaced or washed almost as frequently.