What is a Gasper?

A gasper is an aviation term referring to the adjustable air outlet situated above each passenger seat. These outlets are part of the aircraft's air conditioning and cabin air recirculation system and may feature adjustments for both direction and strength of air flow. They are typically round vents situated above passenger seating with a flow control dial and, in some cases, a directional nozzle. In older aircraft, these outlets were fed directly from the aircraft's packs or air conditioners. In newer planes, the gaspers are fed from the air recirculation system.

The cabins of pressurized passenger aircraft are maintained at a pleasant temperature and supplied with a constant supply of fresh air by several air conditioning units known as packs. This air flow is achieved through a series of strategically placed inlet and outlet vents. Each passenger seating position is, however, also equipped with a supplemental ventilation supply for increased personal comfort. These ventilation points are known as gaspers and can be adjusted by the passenger to supply more or less air flow or be closed off altogether. In some cases, a clamshell nozzle can also be adjusted to change the direction of air flow.

Gasper outlets are fed by a fan or fans which feature a master control on the flight deck overhead air conditioning panel. These outlets feed supplemental air flow to the passengers during ground operations and in flight but may be turned off during takeoffs and landings. This procedure is meant to maximize bleed air availability; as soon as the initial part of the climb-out is complete, the packs and recirculation or gasper fans switch back on.

Older aircraft such as the Boeing 737 100 and 200 series featured gasper systems fed directly from the aircraft's air conditioners. A gasper fan boosted pack air through a series of risers and ducts to the passenger outlets. This fan was usually used during periods of high pack demand and low system pressure. These gasper fans supplied much needed additional fresh air on very hot days while the aircraft was still on the ground.

Newer aircraft feature gaspers which receive their air supply from the cabin recirculation system. This system constantly removes, filters, and recirculates cabin air. This process reduces the bleed air requirements and pack loads, thus increasing performance and lowering fuel consumption. In either case, the passengers receive a source of additional ventilation to ensure comfort during the flight.

Turning off the gaspers via the main switch may help save precious bleed air supply which aids in making safe take-offs and climbs to altitude, but it is not healthy or safe to have them off for long.

Another aspect of gaspers beyond providing some comfort to individual passengers is that they help keep air circulating and fresh throughout the cabin as well. Stagnant, unmoving air often creates an environment in which bacteria, viruses, and molds thrive. Planes are already tight, enclosed spaces full of many people and things so having good air flow helps ensure that any pathogens present on the plane are less likely and able to spread and contaminate everyone on board.

The small gaspers overhead of each passenger now also dispense air that has been run through a top-notch filtration system on most planes as well. Contrary to popular belief, gasper air is quite clean air, even if it is mostly or completely from recirculated cabin air, because of these high-tech filtration systems. Most planes use HEPA filters, which stands for high efficiency particulate air filters. HEPA units are specifically designed to help clean many pathogens out of the air along with other pollutants. Most HEPA filtration systems are rated effective at removing a vast majority of airborne contaminants. Generally, the air coming out of a gasper is cleaner and fresher than the surrounding air is then thanks to these filtration systems despite being originally largely pulled from the surrounding air.

So what exactly is the makeup of the air coming out of those little nozzles? Normally, it is a mixture of fresh air from outside and reused air from the current supply found on the plane. All the air that comes out of the gaspers, whether fresh or not, is first filtered then disbursed. The recirculated cabin air is also completely disposed of far more often on a plane than any other indoor location a person might typically frequent, so the air people begin with before takeoff is not the exact air as they end up with once they land.

There are a couple of common myths or misconceptions regarding the air that gaspers release. One notion is that pilots limit the amount of oxygen that flows out of the gaspers. The reality is that the oxygen content in the air is the same with or without the use of the gaspers. The general oxygen content of the aircraft is lower than what many individuals would consider normal, but it has nothing to do with the gaspers. Instead, air cabin pressure requirements for safety and comfort reasons generally relate to higher elevations in the low to middle thousands of feet. Because of this, the oxygen levels are more akin to those found high in the mountains rather than those found at or just above sea level where most people exist the majority of their time. Generally, these lower levels are tolerable though. For the majority, these lesser quantities rarely lead to oxygen deficiency conditions like hypoxia (low oxygen quantities in your muscles and organs) or hypoxemia (low oxygen quantities in your blood). These conditions still occur though, particularly in individuals who already struggle with getting or keeping oxygen in their bodies. Many health professionals recommend that those with oxygen deficiency, heart, or lung problems discuss these issues with their doctor before flying. Some illnesses and problems may even require supplemental oxygen use during flight.

Another common misconception is that gaspers are the reason the air is drier in a plane. Again, this is incorrect. While the dryness people detect inside plane air is actually there, it is not because of air constantly blowing out of the gaspers. Drier air exists in the plane no matter how many gaspers are on or off at any given time. The main reason for this is that humidifying air requires large quantities of water. The amount of water required to humidity the air would be much too heavy to fly in addition to all the passengers and cargo. It would also take a significant amount of space to store the liquid, and most planes do not have the necessary area available. Humidity also creates a better breeding ground for fungus, mold, and bacteria, so low air humidity on planes creates healthier air as well. 

With all this in mind, manufacturers design plane air systems to humidify the air at much lower levels if at all, which is why it is important to stay hydrated on a plane at all times.