AIR SANITATION

 AIR SANITATION           

·       Air sanitation is a process of control of microorganisms in air.

·       Air sanitation is the system of removing the impurities present in air inside buildings to protect people from infections.

·       Sanitation of air is essential in enclosed places like

ü  Hospital wards

ü  Operation theatres

ü  Burns unit to prevent infection

ü  Food processing and packaging industries

ü  Rooms where sterile materials or products are stored require aseptic atmosphere.

DEVICES USED FOR AIR SANITATION

1) Ventilation

·       Ventilator is an opening or a device that allows fresh air to enter into an enclosed space.

·       A great reduction in the airborne microorganisms can be brought about by laminar airflow system developed by Whitfield.

·       It was found that a horizontal flow of air at about 40 feet/minute in a room in which spores of Bacillus subtilis had been liberated, led to a diminution in their numbers by 100—1000 times greater than that to be expected in a room where turbulent ventilation was employed.

·       The ultimate criterion of its effectiveness must be the diminution of cross infection.

2) Safety Cabinets

·       Safety Cabinets are essentially isolation chambers that provide a safe environment for the manipulation of pathogenic microbes.

·       Safety Cabinets are characterized by having considerable negative pressure air flow that provides protection from infectious bio-aerosols generated within the cabinets.

·       Safety Cabinets are of three classes.

Class I Exhaust protection cabinets

They protect the operator by maintaining a rapidly moving stream of air, which entrains infectious particles and deposits them on a high efficiency filter. The air is then discharged outside the building.

Class II Laminar flow cabinets

These are open-fronted and are designed to protect the material that is being handled from extraneous contamination. It is suitable for most work with moderate pathogens. They do not protect the operator, though they can be modified to do so.

Class III cabinets

These are used for the handling of very dangerous materials and are completely enclosed. Materials are handled through gastight glove ports and air enters through a non-return valve and is extracted through a high-efficiency filter.

 

AIR SANITATION METHODS

1) Filtration of Microorganisms

·       High Efficiency Particulate Air Filter (HEPA) filter will filter micron sized particles at about 95 % efficiency.

·       HEPA filters are Box type filters or Bag type filters.

a)     Box or Pleated type HEPA filters can be as thin as 2 - 4 inches, or as wide as 8 - 12 inches.

b)    Bag type HEPA filter, which can extend upto 24 inches.

·       Bag type filters typically have a lower pressure drop than the Box type HEPA and are more efficient.

·       HEPA filters are typically rated as 99.97 % effective in removing dust and particulate matter.

·       HEPA filters have effective pore sizes of 0.3 µm, small enough to capture Bacterial cells, Endospores and many viruses, as air passes through these filters, nearly sterilizing the air on the other side of the filter.

·       HEPA filters are commonly found in Hospital isolation rooms, Operating theatres, Pharmaceutical manufacturing units and Industrial clean rooms.

2) Ultraviolet Germicidal Irradiation (UVGI)

·       Microbes are uniquely vulnerable to the effects of light at wavelengths at or near 260 nm due to the resonance of this wavelength with molecular structures.

·       Ultraviolet light possesses just the right amount of energy to break organic molecular bonds. This bond breakage translates into cellular or genetic damage for microorganisms. The same damage occurs to humans, but is limited to the skin and eyes.

·       Viruses are especially susceptible to UVGI more than bacteria.

 3) Fumigation with Disinfectants

·       Fumigation is an effective form of disinfection, as gas can spread rapidly within the space to be disinfected, and all the hidden corners and blocked surfaces.

·       The disinfectant is vapourized (by heating or boiling) into fine droplets using a fogger and blown into the air. Upon settling down, these droplets reveal their effect.

·       Formaldehyde fumigation has long been an accepted method for areas where microbiological cleanliness is required.

·       Vaporized Hydrogen peroxide is a dry gaseous method that has been used as a reliable alternative for Formaldehyde.

Glutaraldehyde is rapidly effective against a wide range of microorganisms, but has toxic health effects, and may leave a greasy residue.