Since the first operating room using air cleaning technology was born in the United States in January 1966, the provision of clean operating rooms has become an important symbol of hospital modernization in various countries. With the improvement of people's living standards in China and ever higher demands for health, coupled with the impetus of hospital grading and assessment, in the past 10 years the number of clean operating rooms built in Chinese hospitals through renovation, expansion, and new construction has reached a thousand, involving nearly a hundred hospitals. Since there are 15,270 hospitals at or above the county level nationwide, as many as 7,498 hospitals with more than 100 beds, and 788 hospitals with more than 500 beds, this technical transformation and renewal work will continue to develop even faster. On the one hand, this is a good thing, but on the other hand it is also worrying. What is worrying is the quality. Because in recent years the domestic cleanroom construction market has been rather chaotic—unlike the early 1960s, when cleanrooms were regarded as very mysterious and handled with great caution—now anyone dares to build cleanrooms, and it seems everyone can build them well, as if raising them to any class takes hardly any effort. Wherein lies the secret? It turns out that an air volume several times larger than that required under dynamic conditions was used, while the results were measured under the as-built (empty) state; in some cases the measurement was even carried out by the constructors themselves, and the methods did not comply with the requirements of the standards. But a large supply air volume is of no use: in some laminar flow operating rooms the air velocity over the operating table is extremely low; in some, not only is the operating room at negative pressure relative to the clean corridor, but the clean corridor is also at negative pressure relative to the outside, and no amount of adjustment can correct it; in some, the noise is very loud; in some, the fresh air is far too little, so much so that in one large hospital an operating room nurse fainted while on duty; and due to poor airflow and severe filter leakage, some cardiac operating rooms have been unusable from the day they were completed, with bacterial concentrations even higher than before any air cleaning was installed, and repeated patching has been of no avail. Of course, there are also those who do not understand, or who deliberately deceive, using means that are not laminar flow at all and claiming laminar flow Class 100 on the basis of a single dust particle count figure alone.

On the other hand, the requirements of the construction parties show a tendency toward seeking the high and the foreign. They regard the clean operating room mainly as a matter of decoration, as if in fit-out the higher and the more foreign the better, and at one stroke they build a dozen or so rooms with a complete range of classes.

The above reality tells us that although China has had design standards for general hospitals, a standard specifically targeting clean operating rooms is still needed. Three years ago, the military took the lead in formulating such a standard, and today it has already played a role of reference and guidance. In order to formulate such a standard suitable for the whole country, under the leadership of the Department of Planning and Finance of the Ministry of Health and the Medical and Health Construction Professional Committee of the Health Economics Society, a national standard for hospital clean operating departments is being formulated. Since it is still in the process of being drafted, it is not yet possible to introduce it to everyone in detail, but the principles considered by the drafting group can be described in general terms, which is also for the purpose of soliciting more opinions and obtaining help from colleagues across the country.

(1) Infection control should be a concept of comprehensive control, cutting off all pollution routes. It is not enough for the operating room alone to be clean; the cleanliness requirement should be carried through to an area comprising the operating room and its necessary supporting auxiliary rooms. This area is the operating department, that is, the clean operating department. When building clean operating rooms, there may be just one or two of them themselves, not necessarily with a complete range of classes, or however many, but their necessary supporting auxiliary rooms must be placed within this area and must also be clean, although the requirements may of course differ.

(2) Infection control is also a concept of whole-process control, requiring that the entire surgical process be brought under control. Why have the methods of medicinal fumigation and ultraviolet irradiation already become outdated? It is because they can only provide control at a starting point. Moreover, as pointed out by the World Health Organization (WHO), "since the effectiveness of ultraviolet radiation is limited, it must not be used to replace chemical disinfection." During the entire subsequent surgical process, with the movement of personnel coming in and out, and especially as a result of the air-conditioning air supply, the aseptic state of the room that had just been disinfected immediately vanished completely. Many All measurements have proven that the airborne route is an important route of infection. What is more, today in our country medical technology has improved and medical equipment has become advanced, yet the air condition alone has deteriorated: the dust and bacterial concentrations in our country's air are several times higher than in developed countries. In particular, operating rooms in the future cannot possibly shut air conditioning out, while air-conditioning air alone is an enormous source of bacteria. Under conditions of strict disinfection, airborne infection becomes the principal contradiction of operating room infection. Therefore, the development direction of operating rooms should be to have both routine and effective disinfection and sterilization and, at the same time, to employ air cleanliness technology. As long as there is air exchange in the operating room, air cleanliness technology must be used; air-conditioning air alone that has not met purification requirements is not allowed to enter the operating room (of course, the same applies to clean wards). In short, ordinary air conditioning is not allowed in clean operating rooms.

Air cleanliness technology not only has the function of preventing external bacteria from entering the operating room; the German medical and health community has also found that it is an effective means of preventing the massive proliferation of specific bacteria indoors after long-term disinfection has destroyed the balance of bacterial species. Abroad, in addition to the above two functions, clean operating rooms—compared with our country—also emphasize that they can reduce losses from possible litigation, because if problems arise after surgery, for example infection after cosmetic surgery, and the air environment is below standard, the hospital will be pushed onto the defendant's seat; our country, which has embarked on the road of rule of law, will sooner or later encounter this situation as well.

(3) Since the operating room takes bacterial control as its primary objective, and under the condition that strict disinfection measures for people, hands, surfaces, and so on must be in place, while the cleanliness control of the airflow process must rely on air cleanliness technology, the clean operating room should aim its primary objective at air purification, and the decoration of the envelope structure should be placed in a subordinate position—especially since its dust and bacterial generation originally accounts for less than 10% of the whole room, or even less.

(4) Although air purification is the principal contradiction of the clean operating room, the clean operating room is, after all, a multifunctional comprehensive whole; it is not a matter of being satisfied once the dust count or the bacterial count is sufficient. In the narrow sense, dust, bacteria, velocity, pressure, sound, light, and electricity all have their indicators. It is inconceivable that a room with not a single bacterium, but where the noise makes the chief surgeon's head swim and even affects talking with the assistants, could be a qualified operating room. In the broad sense, it is not enough for the air-conditioning purification to be good; if the building design is irrational, the automatic control unreliable, or the gas supply insufficient, the function of the operating room will also be affected.

(5) As far as air purification is concerned, where local purification can solve the problem, whole-room purification should not be used; where low-grade turbulent flow can solve the problem, high-grade laminar flow should not be used. In 1977, purification workers in our country first proposed the concept of local purification, that is, targeting the objective at a local area rather than the whole room, so as to create a locally clean environment; in 1978, the concept of the main flow zone was first proposed, that is, the cleanliness in a zone beneath the filter is much higher than that of the surroundings, and the work area should be placed within the main flow zone as far as possible. In building clean operating rooms, we should likewise advocate local purification and the turbulent flow mode, promote the application of the main flow zone concept, advocate combining these two concepts, and strengthen the awareness of protecting critical areas. Both theoretical calculation and practice show that this can reduce the bacterial concentration at critical areas to 70% or even 20% of that at the periphery. Germany, thousands of miles away, although not using the name "main flow zone," also formed in 1977 this line of thinking, different from that of other countries, reducing the bacterial concentration in the critical zone to half of that of the whole room. We should break through the framework of industrial clean rooms in the similar British and Japanese standards and absorb the German standard's idea of protecting critical areas, and, based on the important domestic theories and achievements concerning the main flow zone, put forward a scheme for protecting the surgical area that is more systematic, clearer, and more specific than the German standard, so as to achieve high-standard cleanliness with low-standard investment.

(6) Both dust concentration and bacterial concentration should be acceptance criteria for clean rooms, while the control standard can be the bacterial concentration. The bacterial standard for clean operating rooms should be consistent with the current hospital disinfection standards; it cannot be lower than them but only higher. The standard set by the disinfection method for ordinary operating rooms is an airborne bacterial concentration, measured by the settling method and converted, of $leqslant 200$ CFU/m$^3$; this can serve as the minimum standard for rooms of the clean operating department. Our classification standards should be neither too many nor too few; generally there should be three categories: high, medium, and low. Except for neurosurgery, full-body burns, hip joint replacement, organ transplantation, cosmetic surgery, and other treatment rooms with high infection rates, which may adopt high standards, medium and low standards should be applied as much as possible. If the aforementioned main flow zone concept is applied, then even with medium and low standards, the level in critical areas can be raised by one grade.

(7) By what should the quality of a clean operating room be evaluated? Who has the final say? To this end, a strict acceptance system must be established. Apart from the original design review, the basis for acceptance is, in the end, letting the data speak; therefore, after the completion of the project, there must be a comprehensive evaluation of overall performance conducted by a third-party authoritative institution. The standard for the evaluation is our own country's standard. No matter which country's company To undertake the construction of a clean operating room in China, one must act in accordance with Chinese standards.