EPA Partnership with Indoor airPLUS focused on Ventilation and Air Quality
in Offices

Millions of Americans work in buildings with mechanical heating, ventilation, and air-conditioning (HVAC) systems; these systems are designed to provide air at
a comfortable temperature and humidity levels, free of harmful concentrations of air pollutants. While heating and air-conditioning are relatively straightforward operations, the more complex processes involved in ventilation are the most important in determining the quality of our indoor air.

While many of us tend to think of ventilation as either airmovement within a building or the introduction of outdoor air, ventilation is actually a combination of processes which results in the supply and removal of air from inside a building. These processes typically include bringing in outdoor air, conditioning and mixing the outdoor air with some portion of indoor air, distributing this mixed air throughout the building, and exhausting some portion of
the indoor air outside. The quality of indoor air may deteriorate when one or more of these processes is inadequate. For example, carbon dioxide (a gas that is
produced when people breathe), may accumulate in building spaces if sufficient amounts of outdoor air are not brought into and distributed throughout the building.
Carbon dioxide is a surrogate for indoor pollutants that may cause occupants to grow drowsy, get headaches, or function at lower activity levels. There are many
potential sources of indoor air pollution, which may singly, or in combination, produce other adverse health effects. However, the proper design, operation and maintenance of the ventilation system is essential in providing indoor air that is free of harmful concentrations of pollutants.