Source Control
Usually the most effective way to improve indoor air quality is to eliminate indiidual sources of pollution or to reduce teir emissions. Some sources, like those that contain asbestos, can be sealed or enclosed; others, like gas stoves, can be adjusted to decrease the amount of emissions. In many cases, source control is also a more cost-efficient approach to protecting indoor air quality than increasing ventilation because increasing ventilation can increase energy costs.
Source: "The Inside Story: A Guide to Indoor Air Quality" USEPA and the United States Consumer Product Safety Commission Office of Radiation and Indoor Air (6604J) EPA Document # 402-K-93-007, April 1995