Aerobiological engineering

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Aerobiological engineering is the science of designing buildings and systems to control airborne

At a minimum, ventilation systems provide dilution and removal of airborne contaminants, which in general leads to improved indoor air quality and happier occupants. If filters are checked and replaced as needed, they can form an integral component of an immune building system designed to prevent the spread of diseases by airborne routes. They can also be used for pressurization of areas within buildings to provide contamination control.

Biocontamination in ventilation systems

Ventilation systems can contribute to the microbial loading of indoor environment by drawing in

In order to keep patients safe, hospitals use a range of technologies to combat airborne pathogens. Isolation rooms can be designed to feature positive or negative air-pressure flows. Positive-pressure rooms are used when there are patients who are extremely susceptible to disease, such as HIV patients. For these patients, it is paramount to prevent the ingress of any microorganisms, including common fungi and bacteria that may be harmless to healthy people. These systems filter the air before delivery with a HEPA filter and then pump it into the isolation room at high pressure, which forces air from the isolation room out into the hallway. In a negative-pressure system, the focus is on keeping infectious diseases isolated by controlling the airflow and directing harmful aerosols away from health care workers and other occupied areas. Negative pressure isolation rooms keep contaminants and pathogens from reaching external areas. The most common application of these rooms in the health industry today is for isolating tuberculosis patients. To do this, the air is exhausted from the room at a rate greater than that at which it is being delivered. This makes it difficult for airborne disease to go from a contaminated area to a hospital hallway, because air is constantly being drawn into the room rather than escaping from it.

Air sterilization processes

The normal means for filtration in healthcare facilities is low-efficiency air filters outside the air-handling unit followed by the HEPA (High Efficiency Particulate Air) filters placed after the air-handling unit. To be HEPA-certified, filters must remove particles of 0.3 μm diameter, with at least a 99.97-percent efficiency. Air burners sterilize air that is leaving contaminated isolation rooms by heating it to 300 °C (572 °F) for six seconds. Ultraviolet germicidal irradiation (UVGI) is another technique for special-purpose air sterilization. It is defined as electromagnetic radiation in the range of about 200 to 320 nm, that is used to destroy microorganisms. When HEPA filters are used in conjunction with UV sterilization tools, the results can be extremely effective. The filter will remove the bigger, hardier spores, and all that is left are the smaller microbes which are killed more efficiently by the high-intensity UV treatment.

See also

• Human habitat
• Human outpost (artificially created controlled human habitat)
• Legionnaires Disease
• Aerobiology

References

• C.S. Cox The Aerobiological Pathway of Microorganisms. Chichester G.B.: John Wiley & Sons 27, p. 118-119.
• Godish, Thad. Indoor Environmental Quality. Boca Raton, FL, USA: Lewis Publishers, 2001. p. 190.
• Kowalski, Wladyslaw Jan. Aerobiological Engineering Handbook. Blacklick, OH, USA: McGraw-Hill Professional Publishing, 2005. p. 6, 185, 231, 260, 528, 530.