Commercial HVAC systems are prone to other types of problems because of their complexity. With immature immune systems, children are often the most susceptible members of our society to indoor pollution. To expose a child to the volatile chemicals outgassed from recent remodeling in a school makes very little sense. It has been shown that children living in homes with wood stoves have a significant chance of developing respiratory symptoms. The outdoor air pollution in areas where wood burning is common attests to the fact that in many cases, wood is not a clean fuel.
Unborn children are also at increased risk, as are pregnant women, and the elderly and the infirm.
Hopefully, we have progressed beyond the level of cavemen sitting around a fire. A fire outdoors is polluting enough, and there is no good reason to bring it indoors. In Scandinavia, it is common to locate a natural gas furnace outside the house, in order to avoid polluting the living space. This idea could easily be adapted to houses in the Unites States. If a normally aspirated combustion furnace must be located indoors, it should be atmospherically separated from the house.