Critical points in the design and construction of negative pressure clean room wards for infectious diseases
As a deep design and construction unit of negative pressure wards, we hope to put forward the following requirements and suggestions for the design, planning, and construction of future negative pressure wards from our professional perspective and wish to communicate with the majority of medical construction practitioners Common exchanges provide more thinking for the future development of the hospital construction industry.

Youth is a professional cleanroom supplies manufacturer in China, our products include clean room air filters, cleanroom equipment, and also cleanroom furniture. In this post, we will share with you the negative pressure clean room layout design.

I Layout design

1.The negative pressure ward should design according to the requirements of the Type A virus. The design basis should meet the standard needs put forward by the Ministry of Health based on higher standards. The isolation and control technology should adopt, but the biosafety technology should be fully considered.

2. The negative pressure ward should strictly follow the functional zoning and medical procedures and set up three zones, three buffers, and three channels.
(1) Three areas: clean area (medical office area), semi-contaminated area (auxiliary room), contaminated area (isolation ward, dirt channel);
(2) Three buffers: the clean zone enters the semi-contaminated zone buffer zone, the ward entrance buffer zone, and the patient passage buffer zone;
(3) Three channels: staff channel, patient channel, and dirt channel; the flow of people and logistics must follow a one-way process. Medical staff and patients, cleaning materials, and contaminated materials have their independent entrances and exits and strict flow routes. (See below)

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3.Since the medical staff enter the work area (semi-contaminated area) from the cleanroom through the dedicated passage; the patient enters the ward from the patient entrance and the reliable transportation to receive treatment, and can only move in the community during the treatment, so the logistics has divided into cleaning and pollution,need to enter and exit from different entrances and exits.

Clean items such as food and medicine are passed by the staff to the front room of the ward, and enter the neighborhood through the pass box; the dirt and household garbage are collected and sealed by the team, and then sent out of the ward through the dirt channel.

The pressure gradient

Infected patients will spread the virus through particles and droplet nuclei in the air. The size of these particles is 1 to 5 microns. Normal air can make them stay in the air in the room or building for a long time. Therefore, the negative pressure isolation ward’s focus is the ventilation system, which is also the core of such projects.

The negative pressure ward first needs to design the pressure gradient. The pressure gradient of the negative pressure ward should be in order: staff office clean area → clean area corridor → extra room semi-contaminated area → semi-contaminated area corridor → contaminated area patient corridor → Negative pressure isolation ward → bathroom, step by step. (See below)

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The airflow direction is controlled by the pressure gradient (negative pressure) from the higher pressure area to the lower pressure area. A relatively stable airflow can be formed, and the pollution source is controlled not to spread.

III Air conditioning system

An orderly air pressure gradient can achieve a directional flow of air from a clean area to a polluted area.

1. By reasonably arranging the inlet and exhaust outlets, the indoor airflow first passes through the medical staff’s working area. It then enters the exhaust duct through the exhaust outlet at the bottom of the bed head, forming a directional and stable airflow organization.
2. To prevent the cross-infection of patients in different wards in the infectious disease area, the airflow organization should design according to the site and adopt a new air conditioning system to avoid cross-infection and a reasonable system layout. Also, from the perspective of energy saving, it is recommended to adopt a variable air volume air conditioning system based on ensuring the pressure gradient in the ward. The patient corridor can only be provided with an exhaust system without considering the air conditioning system. (See below)

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4.Under the premise of meeting the current epidemic situation’s needs, we should also consider how to use it as a general ward after the epidemic. It recommends that the isolation ward equip with a return air switching device during the design process. It can be switched to general control when it is not necessary to increase the community. The utilization rate reduces operating energy consumption so that its investment can maximize the value.

5.The air supply in the ward should adopt the directional flow air supply method, with the top delivery side and the subsequent return (row). It is recommended to install an ion sterilization and inactivation device with human and machine coexistence in the air supply pipe, send ions into the ward with the fresh air, and actively and effectively inactivate the suspended colonies in the room.

6.The arrangement of the air outlets should be conducive to the control of pollutants. The positioning of the delivery and return (exhaust) air outlets enables clean air to first flow through the possible working area of the staff in the room and then flow through the patient’s source of infection into the return (exhaust) air outlet. Avoid the occurrence of blind areas of air circulation, stagnation of airflow, and short circuits of supply and exhaust air.

6. The air volume detection and alarm device should be installed at the end of the air supply and exhaust outlets. The end of the exhaust system is equipped with a high-efficiency filter device or a biological elimination and inactivation treatment device to prevent pollution sources from being discharged outdoors with the exhaust system, causing secondary pollution to the outdoor environment.

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IV The control system

A good pressure gradient design must be combined with an effective control system to be realized.
1. For the air-conditioning control measures required for the negative pressure isolation ward, a specific pressure difference control should be adopted between each area (the primary purpose of the pressure difference control is to prevent pollutants from spreading from the polluted area to the cleanroom), so that the clean and the dirty regions Reasonable airflow and directional flow are formed between them, and the pressure difference requirements of each area are realized by adjusting the difference between the air supply volume, the return air volume, and the exhaust air volume. (www.clanroomfactory.com)
2. It is recommended that the control system has an alarm function. When the fresh air filter is blocked, the pressure difference is abnormal, or a general failure can give an alarm.
3. Differential pressure sensors should be installed in each area to monitor each room’s pressure gradient in real-time through the intelligent control system and maintain the gradient pressure difference of each size in the negative pressure ward at any time and in any operating state. Simultaneously, according to the community’s needs, when the pressure gradient of the switching system is the ordinary ward, it can also be realized through the control system.

V Decoration

1. To facilitate cleaning and disinfection, the architectural decoration, floor, and wall of the negative pressure ward should meet the requirements of no dust, no bacteria, no dust, no bacteria, no moisture absorption, no moisture permeability, easy to clean, and disinfect.
2. The inner surface of the enclosure structure in the semi-contaminated area must also be smooth, corrosion-resistant, and waterproof to be easy to disinfect and clean, and all gaps should be reliably sealed
3. The intersection angles between the ceiling, floor, and walls should all be arc-shaped and reliably sealed. The ground should be leak-proof, seamless, smooth, and non-slip. A sizeable transparent observation window should be installed on the side of the corridor facing the medical staff. It is recommended to install an intercom device next to the observation window.
4. Negative pressure wards should be equipped with interface devices for bedside treatment facilities such as oxygen and suction and call, intercom, and lighting facilities. The bedside should have not only enough space for bedside X-ray machines, ventilators, and other equipment, but also enough space for living facilities such as televisions, drinking fountains, desks, etc., and set up power sockets, telephones, cable TV ports, and closed circuits—the camera of the surveillance system.
5. All doors in the negative pressure isolation ward should be equipped with automatic door closers, and the entries in the area should be opened to the side with high pressure to increase the airtightness of the door. The glass windows in contaminated and semi-contaminated areas must be sealed. The holes between all types of lamp boxes and ceilings should also be locked and airtight to ensure that the penetrating part fills when any pipeline leads to the isolation ward through the top.
6. The ground construction should also be wear-resistant and non-slip.
7. The location design of the negative pressure isolation ward should also thoroughly consider natural lighting and then use transparent glass partitions to give natural light and even natural landscapes as much as possible to relieve the patient’s depression and anxiety to a certain extent and help treatment and rehabilitation.

This is a battle involving all the people. There are no bystanders and no outsiders. As a supporter and participant of the “anti-epidemic,” we hope to do our best, with professional knowledge, products, and full enthusiasm, to become a strong backing for the front-line medical staff of the “anti-epidemic” to serve the construction of hospitals and fight the epidemic Go all out!
May the epidemic end as soon as possible!