THIS chapter introduces the field of environmental health as it pertains to the indoor environment@ briefly covering problem identification@ control@ and regulations. The role of HVAC professionals in delivering clean@ appropriately conditioned air and removing contaminants is vital@ both in industrial and nonindustrial environments@ making some knowledge of indoor environmental health helpful. Architectural@ structural@ cleaning@ maintenance@ materials use@ and other activities that affect the environment often are outside engineers' control; nevertheless@ whenever possible@ the HVAC professional should encourage features and decisions that create a healthy indoor environment.