Environmental researchers are focusing on indoor air pollution, as a result of reports of symptoms or specific diseases that occur mainly in air-conditioned and mechanically ventilated buildings eg. offices, hotels, conference halls, restaurants, apartments, shopping malls etc.
Studies have proved that at mostly urban locations, level of contaminants in the indoor air are often several times higher than outdoor air. This combined with the fact that people tend to spend 90% of their time indoors, results in their being exposed to airborne contaminants indoors, most of the time. The term ‘Sick Building Syndrome’ is an outcome of poor IAQ (Indoor Air Quality), which refers to the physical, chemical and biological characteristics of air in the indoor environment.
Poor ‘Indoor Air Quality’ is a direct reference to the presence of:
- excess CO2 levels
- volatile organic chemicals, formaldehyde, solvents etc. which are given off from the furnishings, carpets, paints etc. over a period of time.
- odors from food, body odor, cigarette smoke, perfumes etc.
- microbial growth due to high humidity.
An effective solution to poor ‘Indoor Air Quality’ has been by the method of dilution, wherein outside fresh air is brought in by “Energy Recovery Ventilators”, which also serve to transfer most of the chilled (or heated) energy of the exiting stale air to the entering fresh air, without any significant increase in the air-conditioning costs.
However, it has been noted that even after using such ventilation systems in certain areas, complete control of all parameters had not been achieved. These are areas having:
- excessive odor generation eg. restaurants, smoking areas etc.
- increased load (occupancy and activities) than designed.
In such areas, dilution control necessarily has to be supplemented by ‘removal control’. Use of Dry Air Scrubbers charged with virgin Activated carbon and impregnated Activated alumina, working on the re-circulation mode is strongly suggested, either operating alone or in conjunction with an effective ventilation system.