Operating room air pressure according to the different regions (such as the operating room, sterile preparation room, scrub room, a clean room anesthesia and the surrounding area, etc.) the cleanliness of the different requirements and different.  Different levels of laminar flow operating room air cleanliness standards of its different HEPA filter, HEPA filter, air filter - HEPA filter used in hospital operating rooms, such as the U.S. Federal Standard 1000 cubic feet of air per The number of dust particles ≥ 0.5μm, ≤ 1000 SVs or per liter of air ≤ 35 stars. 10000 standard laminar flow operating room for each cubic foot of air in the number of dust particles ≥ 0.5μm's, ≤ 10000 SVs or per liter of air ≤ 350 stars. The main purpose is to exclude the operating room ventilation exhaust within each workplace; ensure that all workplaces necessary amount of fresh air; remove dust and microorganisms; maintain indoor necessary positive.  Able to meet the requirements of the operating room ventilation mechanical ventilation has the following two.  Mechanical ventilation with mechanical ventilation and formula: This ventilation can control the number of ventilators, ventilation and indoor pressure ventilation is better.  Mechanical ventilation and natural ventilation and use, ventilation and air changes this subject to certain restrictions ventilation, ventilation as effective as the former.  Mainly clean operating room level of dust particles in the air, and the number of biological particles to distinguish. 。 Currently, the most commonly used is the NASA classification. Purify air purification technology by positive air flow control to achieve sterile cleanliness purposes.

 Health industry is a very large and special industry, its air cleanliness requirements are high. Typically, the minimum requirements for hospital use efficiency of the air pre-filter and a 30% efficiency of the filter is 90% of the final combination of filtration. Under normal circumstances does not require HEPA filters, but in exceptional circumstances, such as isolation rooms, specific tests and care area will need to HEPA filters.

 Many HVAC systems to use 100 percent of the hospital's outdoor air, which is for the patient to prevent cross-infection by microorganisms suspended HVAC system is a good strategy.  But 100% outdoor air does not eliminate microbial growth and its adverse effects on the environment of care in the air filtration media.  So now many hospitals are still in dire need of advanced HVAC systems.

 Cleanroom health system was first used in the operating room.  It just started to get widely used in orthopedic surgery, orthopedic surgery since a long time, easy to cause infection. The desirable level of control is to use clean air reaches the operating table 100 near. Generally recommended to use the top of the HEPA filtration system that can cover at least 3 m × 3 m area, which included the operating table and the people.

 Depending aspirated mode, the purification techniques can be divided into two turbulent and laminar flow systems. (1) turbulence system (Multi-Directional Manner): turbulent systems and high efficiency filter outlet located in the ceiling, back or sides of the outlet located at the lower side of the wall, filters and air treatment is relatively simple, easy expansion low cost, but fewer ventilation, usually 10 to 50 times / h, prone vortex particle pollution indoors may be suspended circulating vortex area, forming pollution airflow, reduce indoor purification degree.  NASA standard applies only to 1000 000 10 000 clean room. (2) laminar flow system (Laminal Flow System); laminar flow and velocity distribution systems utilize proper airflow, high efficiency air filters, HEPA filter, air filter - HEPA filter used in hospital operating rooms will particles of dust through the return air to bring out the operating room, no eddy, there is no floating dust, with increasing degree of purification and improved ventilation times for NASA standard 100 operating room. However, the filter seal breakage rate is relatively large, and higher cost.

 Other areas of cleanroom applications have access to the delivery room, nursery, burn room, cardiac care unit, etc.. One of the latest developments is the application of dental surgery cleanroom, which reduces the risk of long-term medical staff during surgery is infection.With the development of high technology, more purification equipment will also apply to the hospital being.