An air outlet is the outermost panel within any type of object that controls the rate in which air passes into the surrounding area. Many air outlets have the ability to be open or shut at varying degrees to restrict the flow of currents coming and going; some of them can also be sealed off completely to stop airflow. This function is especially important within laboratories and other areas where potentially toxic materials are in constant use; without the proper filtration, the air itself could reach life-threatening levels. Other popular names for such a device are air vents, flow vents, or air grills.
The most popular implementation of an air outlet is the vent installed within structures to deliver air conditioning throughout a building. It is normally connected by a series of ductwork that allows the conditioned air to be delivered throughout the dwelling—for areas that require more or less ventilation, the air outlets can be adjusted accordingly. Many air conditioning outlets can also be positioned to provide a directional airflow, such as the vents inside automobiles, airplanes, or sea vessels. These units are customized to allow a single user complete control over the amount of air conditioning within her limited space or area.
Air outlets are also designed as a number of other items that vary by industrial and residential needs. The military, for example, issues each soldier a ventilator system that allows them to breathe contaminated air. While a filtration system within the mask is the essential component that makes this possible, the system would fail to work without an air outlet designed for that specific task. There are also air outlets within parachutes, automatic firearms, and several other forms of modern weaponry. Within residential homes, there are air outlets on almost all major appliances, hair dryers, area fans, and many other items. Businesses use air outlets for everything from safety goggles to massive blower valves that can efficiently expel heat and/or steam from an area, allowing workers to remain within close proximity of extremely temperate equipment.
Although it is difficult to determine when the air outlet was originally invented, ancient Romans implemented them within aqueducts starting in 312 BC. Even earlier civilizations used air conditioning outlets to vent smoke from their homes at least 200 years before then, although there is no recorded text as to exactly how they were made. Some historians believe that the first commercially-used air outlet originated in Egypt around 700 BC, but there is no documentation to support this theory.