The presence of contaminants in the air in concentrations that prevent the normal dispersive ability of the air, and that interfere with biological processes and human economics.
Air pollution control
The use of devices to limit or prevent the release of pollution into the atmosphere.
Air quality standard
A government-mandated regulation that specifies the maximum contaminant concentration beyond which health risks are considered to be unacceptable.
Air register
The component of a combustion device that regulates the amount of air entering the combustion chamber.
Air relief valve
Valve that is used to vent air out of a water system.
Air retarder/barrier
A material or structural element that inhibits air flow into and out of a building's envelope or shell. This is a continuous sheet composed of polyethylene, polypropylene, or extruded polystyrene. The sheet is wrapped around the outside of a house during construction to reduce air in-and exfiltration, yet allow water to easily diffuse through it.
Air rights
Rights to use the open air space above a street, railroad line, or other property. Sometimes used to allow construction of billboards or other signage. Air rights may also allow the construction of entire buildings, such as when a development is constructed over an existing highway.
Air source equipment
Heat pumps or air conditioners that uses the outdoor air to transfer heat to and from the refrigerant in the unit.
Air space
The area between the layers of glazing (panes) of a window.
Air terminal device
A device located in an opening provided at the boundaries of the treated space to ensure a predetermined motion of air in this space.
