What is Air Recirculation?

H. Terry

Air recirculation is when a circulation device moves air in a closed space around more than once. Such devices can serve either personal or commercial purposes. They are used and adapted to a range of circumstance, from homes and cars to industrial buildings and laboratory clean rooms. Air recirculation keeps out, or limits the amount of, outside air coming into a space in order to avoid pollutants, unwanted odors and to aid in air conditioning.

Laboratory clean rooms must have the air quality tested and recorded regularly to ensure the air recirculation system is working properly.
Laboratory clean rooms must have the air quality tested and recorded regularly to ensure the air recirculation system is working properly.

Air recirculation systems recycle air already contained within a space and control the amount of new air entering that space; in many cases, they also pass old air through a filtration system. Simple home fans might be considered a form of this type of circulation although they do not provide filtration and only circulate air within a very limited space.

Some car air conditioning systems recirculate air.
Some car air conditioning systems recirculate air.

Small fans are mainly used to provide an isolated artificial breeze, whereas air recirculation systems are designed to maintain a fixed air flow and indoor air quality throughout a vehicle or building. Recirculating air can also help control temperatures since air conditioning systems can be more effective when re-warming or re-cooling air that has already passed through the system a few times. Buildings in colder climates use the recirculation of air to keep out cold air and to contribute to thermal conditioning.

Air recirculation is commonly seen in laboratory clean rooms.
Air recirculation is commonly seen in laboratory clean rooms.

If not well designed and maintained, air recirculation systems might aggravate respiratory conditions and lead to the spread and concentration of air contaminants. In enclosed areas — most quickly in small ones such as in the passenger compartment of a car — dangerous carbon monoxide levels can develop if fresh air is kept completely blocked from entry for an extended period of time. To deal with this potentially serious problem, many car manufacturers add carbon dioxide detectors as safe-guards to their air conditioning and recirculation systems. People can elect to install carbon dioxide detectors in homes as well and, in some U.S. states and other jurisdictions, installation has become obligatory.

There are certain circumstances in which specially tailored systems are needed for unique purposes. In the case of buildings in which industrial processes are carried out, appropriate ventilation is necessary, and air recirculation systems are designed to regularly bring in needed amounts of fresh air and to expel air that has been contaminated. In a laboratory clean room, which is a room maintained with as few contaminants as possible for research or manufacturing purposes, a particularly powerful airflow is required to ensure sanitation.

Air recirculation can remove particles from the air that cause sinus issues.
Air recirculation can remove particles from the air that cause sinus issues.

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Discussion Comments

alex1986

@YellowMood - It's my understanding that while those kinds of air flow systems work really well, they don't get rid of 100% of the toxins in the air. But, apparently, they can get rid of the bulk of them.

I was thinking of opening a hookah bar and am researching those kinds of products right now.

Does anyone have any idea what particular models of recirculating air conditioners work best in smoke-filled environments?

YellowMood

A friend of mine used to work at a cigar shop that allowed their customers to smoke indoors. I'm not a smoker myself, but when I would visit him at work I was always surprised to see people smoking big cigars 10 feet away from me and I didn't really smell any of the smoke.

Does anybody know if the air exchangers that those kinds of places use actually purify the air? I couldn't imagine that it would be completely harmless to your lungs to stand in there, right?

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