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We all breathe an average of 22,000 times a day, and during that process, we inhale approximately 15 kg of air. The simple opening of a window used to be an adequate solution to obtain a supply of fresh air, but with present day air pollution this is a "thing of the past".
In any occupied enclosed area, the level of oxygen in the air will decrease and the level of carbon dioxide increase as a direct result of human respiration. The more people in a given area, the greater the reduction in air quality.
Without an adequate supply of suitably distributed fresh air, people in an enclosed area can experience physical discomfort, shortness of breathe, headaches, dizziness, lethargy, etc due to the natural diminution of air quality - an effect often referred to a "Sick Building Syndrome''.
In addition to this natural diminution of air quality there are additional contaminants, which affect the air we breathe.
ETS (Environmental Tobacco Smoke) is a well-known and unwanted toxin in air, additional but less well-known contaminants include bacteria, fungi, formaldehyde, radon gas and sundry odours from paints, cleaning chemicals, sanitary facilities etc.
In recent times, there have been alarming developments with regard to communicable airborne viruses, spores, moulds, Aspergillis, the transmission of which is greatly increased by air-conditioning systems which re-circulate the same air within a building.
Most traditional air conditioning systems control the air temperature inside a building, they do not filter or clean the air they re-circulate.
Airborne Infection Control in Health-Care Facilities
Airborne pathogens in health-care environments pose a particular risk to immunocompromised patients who may inhale dust particles that carry fungal spores, bacteria and viruses. Airborne micro-organisms can not only complicate recovery from surgery but also lead to life-threatening infections.
Nosocomial (hospital-acquired) aspergillosis, for example, has been recognised as a cause of severe illness and high mortality in immunocompromised patients, e.g., patients undergoing chemotherapy and/or organ transplants.
In light of the marked increase in nosocomial infections over recent years, many of which are caused by drug-resistent pathogens, the importance of using high-efficiency air filtration systems, beyond the confines of so-called "critical" areas (such as operation theatres), has once again been emphasised. Both the World Health Organisation (WHO) and the Centres for Disease Control (CDC) advise that, wherever possible, preventive infection control measures should be implemented to reduce the risk of nosocomial infections.
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