OT being most critical area in a hospital complex, it is necessary to control OT air in respect of temperature, humidity & particulate matter content of air, micro-organisms i.e. bacteria, viruses, fungi etc. Air handling systems process air through various stages. Air is cooled, moisture is removed, air is filtered to remove dust particles, bacteria, viruses ; some air handling systems additionally remove gases, odour and other volatile organic compounds.

Laminar Air Flow is non-turbulent air flowing in parallel lanes vertically. LAF is filtered air coming over operative area from diffuser plenum above it. Plenum is fitted with HEPA (High Efficiency Particulate Air) filters of 0.3micron at 99.99% efficiency. Many times it is seen that plenum also works as light source above operative area ; it has LED lights inside which provide clear shadow less light over operative area.

It is necessary to maintain particular air velocity in LAF so that filtered air coming over operative area carries bacterial load away from it. According to international standards it should be between 90-120 FPM (feet per minute). NABH (National Accreditation Board for Hospitals & Healthcare) also recommends the same.

Highly clean air of LAF falls in CLASS 100/ISO 5 category. When this air moves further in OT after leaving LAF area it mixes with less clean air of the room along with heat, moisture, bacterial load carried from operative area. It gradually looses it’s clean state and while it reaches the last point in OT from where it is sent back to air handler. Air in peripheral area of LAF normally falls in CLASS10,000 – 100,000 category depending on air handler  & OT size.

LAF can be made in various sizes viz. 6’X2’, 6’X3’, 6’X4’, 6’X6’, 6’X8’, 8’X8’. Apart from these standard sizes any other customized  size can also be made. Air handler has 5 filteration stages in total. First is 10micron pre-filter, second UV, third 5 micron fine-filter, fourth gas-phase filter (optional) and finally 0.3micron HEPA filter. Out of five, first four are fitted in air handler and last i.e. HEPA is fitted in plenum above operative area.

Air handler can include all or part of above first four. Air handler are made in two types ; first is Air Handling Unit (AHU) which is kept outside OT, normally floor mounted or ceiling suspended. Second is Ceiling Suspended Low Pressure Air Handler which is fitted inside OT at ceiling. It can be done for LAF size upto 6’X4’. Air is taken from floor level in OT, sent to air handler, and returned through plenum as LAF. Fresh air is added to this within AHU. Positive pressure is created to restrict outside air entering OT though door etc. Necessary cascade pressure relief dampers are provided in wall to relieve excess pressure in hermetically sealed areas.

Air conditioning is done within air handler to provide required cooling ; no extra a/c is required in OT apart from this. UV treats air to eliminate micro-organisms like bactaria, viruses etc. HEPA plenum can be made in GI powder coat, Aluminium powder coat, SS304.