When indoor air quality (IAQ) is insufficient people often ask for more outside air and higher air exchange rates. However, in many places on this planet clean and fresh outside air is a rare commodity.

To make outside air fit for purpose, it has to be elaborately conditioned, filtered and purified. This solution is costly and the result is not always as expected. During peak demand the air conditioning system may not cope with the increased workload and the rooms will be too hot, stuffy and smelly, as typically encountered in crowded rooms with insufficient air supply.

Commonly, the air supply is controlled according to CO₂ levels. With rising levels the HVAC system will move more outside air into the room. However, long before CO₂ levels approach legal limits, the hygienic limit is exceeded. The air is perceived as smelly and stuffy due to VOCs and organic odors that originate from humans, cooking, cleaning or furnishings. Unfortunately, the offending pollutants are not filtered out in standard HVAC systems and dilution (by introducing of outside air) tends to take a long time.

Adsorption filters take up a considerable amount of space, are very costly to operate and therefore usually not viable. It would be very desirable to treat the air in such a way that it would be free of offensive pollutants and returned into the room in an „immaculate“ state.