Negative or positive pressure rooms are often necessary to prevent contamination and maintain a climate-controlled environment in various applications. While these rooms are somewhat similar, there are certain differences between their designs and requirements. Here we’ll give an overview of both of these types of environments, including their intended applications and design requirements.
Negative Pressure Rooms
Negative pressure rooms have air pressure that is lower than the external air pressure. Negative pressure is achieved through the use of an exhaust system that frequently includes a high-efficiency particulate air (HEPA) filter connected to a sealed room. These rooms can trap potentially dangerous particles to prevent cross-contamination in external air. This is why they’re often used to isolate infected patients while keeping people outside of the room consistently safe.
Negative pressure rooms are designed to contain airborne infections. To do so, there are various design requirements that these rooms must follow, which are outlined by CDC Guidelines, ASHRAE standards, and Healthcare Design Construction Guidelines. As summarized in these guidelines:
- Negative pressure rooms must undergo at least 12 total room air changes every hour.
- They need to maintain a negative pressure differential of at least 0.02’’.
- Exhaust from these rooms and any connected anterooms or toilet rooms needs to travel directly outdoors with no chance of contaminating exhaust from other spaces.
- If an anteroom is included in the setup, airflow needs to travel into the anteroom via the corridor. From there, it should be channeled into the patient isolation room.
- The quantity of air exhaust needs to be higher than the supply airflow to maintain a consistent pressure differential.
- The exhaust grille must be located in the ceiling and near the head of the bed.
- All exhaust air must be discharged through a HEPA filter if the fan is below the roof line.
Misconceptions About Negative Pressure Rooms
One potentially dangerous misconception about negative pressure rooms is that medical personnel are safer when performing aerosol-generating procedures on patients in these rooms. This is due to the Centers for Disease Control and Prevention (CDC) recommendation that these procedures be performed in isolation rooms. However, negative pressure rooms do little to protect individuals inside the room. Their main purpose is to help protect people outside of the room by keeping aerosols and other particles within the room.
Positive Pressure Rooms
A positive pressure room is intended to protect patients from infectious diseases if they’re immunocompromised. While this type of room is somewhat similar in concept to negative pressure rooms, it features certain differences in its function and design. Positive pressure rooms contain a higher pressure in the containment area than the external environment, preventing air from leaving the room and circulating back inside. This prevents occupants in the room from being exposed to any outside contaminants, including potentially harmful particles and germs.
Positive pressure rooms must follow various design requirements to keep patients protected from outside contaminants. Included in these requirements are the following elements:
- Positive pressure rooms require at least 12 air changes every hour.
- They must maintain a minimum positive pressure differential of 0.01’’.
- If anterooms are used, the airflow must travel to the anteroom from the patient room and then into the adjacent corridor.
- Normally, a 150 to 200 CFM airflow difference is sufficient for maintaining the ideal pressure differential in these rooms.
- HEPA filters are required to supply clean air. These filters are normally located at the room’s supply terminals or the main air-handling unit.
- Airflow to the room needs to stay at a constant volume for consistent ventilation.
Create Custom Positive and Negative Pressure Environments with Air Innovations
If you require flexible positive or negative pressure rooms for your application, Air Innovations has the expertise and solutions you need. Our IsolationAir® unit offers a portable contamination control system that can efficiently convert standard-sized patient rooms into either positive or negative pressure environments. Some of the features of our IsolationAir® system include ductwork, UV sterilization, and HEPA filtration connections. The system also allows for temperature control, isolating the room from the central HVAC system.
For more information about our systems, contact us today. You can also request a quote to get started on a custom solution for your project.
Negative pressure rooms control airborne pathogens by exhausting contaminated air from the building while preventing the air from leaking into other parts of the facility. These rooms are a necessity to maintain the safety of guests, patients, and hospital staff.
At Air Innovations, Inc., our expertise in negative pressure HVAC systems will ensure that your hospital’s negative pressure rooms comply with industry standards.
What Are Negative Pressure Rooms?
Negative pressure rooms have inside air pressure that is lower than the air pressure outside of the room. This serves to prevent contaminated air from exiting the room while allowing non-contaminated air to flow into it. Contaminated air flows through a controlled HVAC system, where the air is purified using specialized filters before it exhausts from the facility.
Creating Negative Air Pressure in a Hospital Room
Negative pressure rooms are crucial in hospital settings as they isolate airborne diseases like COVID-19, SARS, and MERS from the rest of the facility and prevent them from spreading to patients, staff, and guests. A negative pressure room requires a dedicated space, where a barrier will keep the room as air-tight as possible. For isolation rooms in more open areas, a heavy plastic curtain can block air circulation. If the area has a door, it is important to block any gaps to create a tight seal.
When establishing an isolation room in a hospital, the HVAC system will require adjustments to ensure the room has a continuous inflow of fresh air. The contaminated air must be forced out through exhaust vents with a filtration system to purify the air before it exits the facility. An existing HVAC system may be suitable, or a portable contamination system can be used to focus on a particular area.
Types of Negative Pressure Isolation Rooms
There are two classes of negative pressure isolation rooms, class N and class Q. A class N room isolates airborne diseases within a room to protect the facility from exposure. They are typically near the entrance of an inpatient ward to prevent the spread of the disease during patient transport.
Class Q rooms also isolate airborne diseases but implement stricter safeguards. Some primary features include an anteroom, self-closing doors, a private restroom to keep the isolation room sealed, and a ventilation system that prevents exhausted air from re-entering the isolation room. Class Q rooms also feature a monitoring system that alerts staff if the pressure changes. These are all crucial features to ensure optimal infection control.
Hospital Spaces to Negatively Pressurize
Various hospital spaces should be negatively pressurized for safety and compliance. According to ANSI/ASHE/ASHRAE standard 170-2017 of the 2018 FGI guidelines, negative pressure spaces include but are not limited to:
- Isolation Rooms for Airborne Infections
- Autopsy Rooms
- Public Waiting Areas and Radiology Department Waiting Areas
- Emergency Department Decontamination Bays
- Various Laboratory Work Areas
- Janitor’s Closets
- Sterile Processing Areas and Soiled Decontamination Areas
- Soiled Workrooms and Holding Rooms
- Soiled Linen Sorting and Storage Areas
General patient examination, X-ray, and nursery areas typically do not require negative pressure rooms.
Testing and Monitoring Room Pressure
Monitoring for consistent low pressure in an isolation room is vital to ensure the safety of a facility. While a tissue or smoke capsule can confirm if the room is pressurized, modern equipment provides continuous monitoring of the room’s pressure. Electronic monitoring devices can be placed inside the isolation room and outside to trigger an alarm when the pressure reaches a set threshold. Regular inspection is necessary to ensure the devices are not contaminated or broken.
Contact the Experts at Air Innovations for Custom HVAC Systems
Negative pressure rooms are vital to controlling airborne diseases in a hospital facility. When setting up a negative pressure room, the experts at Air Innovations, Inc. can create a custom HVAC solution for your facility.
Air Innovations offers specialty environment control units to meet the needs of various critical applications. Our IsolationAir® portable contamination systems deploy quickly to isolate a sterile environment and prevent cross-contamination. These systems come equipped with UV sterilization, HEPA filtration, and ductwork connections. Whether you need to turn a room into a negative or positive pressure environment, our IsolationAir® system offers the ideal solution.
Our expertise will ensure your isolation rooms are compliant with ASHRAE, AIA, and CDC guidelines to protect patients, staff, and guests. Contact us to speak with a representative or request a quote to learn more.
At Air Innovations, we’ve designed, manufactured, and tested custom environmental control solutions for OEMs and non-OEMs for over 30 years. This extensive experience provides us with the knowledge and skills needed to deliver appropriate systems for a wide range of industries. One of the key markets we serve is the healthcare industry. Healthcare professionals know they can rely on us for products that keep their patients and personnel safe and healthy, such as hospital isolation room systems.
Below, we provide an overview of hospital isolation rooms, outlining the types available and key considerations to keep in mind when building one for a healthcare facility. Additionally, we highlight the products we offer that can be used to help build isolation rooms.
WHAT ARE HOSPITAL ISOLATION ROOMS?
In hospitals and other healthcare facilities, controlling the spread of infectious diseases is critical to keeping patients, personnel, and visitors safe and healthy. An important element of a comprehensive infection control strategy is the use of isolation rooms. These specialized rooms are designed to decrease the likelihood of cross-infection among people within the facility by controlling the flow of air within the room to reduce airborne infectious particle levels. They can achieve this goal in a number of ways, including by controlling the quantity and quality of intake or exhaust air, maintaining an air pressure differential between adjoining areas, directing airflow in a specific pattern, diluting room air with large volumes of clean air, and cleaning the air with high-efficiency particulate air (HEPA) filters.
TYPES OF HOSPITAL ISOLATION ROOMS
Isolation facilities can be configured in several ways, including the following:
- Standard Rooms. These rooms utilize standard room (neutral) air pressure levels. They have normal HVAC systems and may or may not have a clinical handwash sink, en suite shower and toilet facilities, and a self-closing door. While they are generally used for patient contact isolation applications, they can be used for normal patient care when isolation is not required.
- Airborne Infection Isolation (AII) Rooms. These rooms—also referred to as infectious isolation rooms—utilize a negative-pressure differential. They have lower pressure levels than adjacent rooms so air will rush inward rather than outward when the room is opened. This design prevents airborne infectious particles from escaping into other areas of the healthcare facility. They are employed as single-occupancy rooms to isolate patients with suspected or confirmed airborne-transmissible infections.
- Protective Environment (PE) Rooms. These rooms utilize a positive-pressure differential. They have higher pressure levels than adjacent rooms so air will rush outward rather than inward when the room is opened. This design prevents airborne infectious particles from entering the room from other areas of the facility. They are utilized to protect immune-compromised patients from airborne-transmissible infections.
KEY CONSIDERATIONS WHEN BUILDING AN ISOLATION ROOM
Due to their critical function, isolation rooms must be designed and constructed carefully. Otherwise, there is an increased risk of cross-contamination between patients, personnel, and visitors. While there are many factors to consider to ensure an isolation room will work properly, some of the key ones include air changes per hour, HVAC, pressure control, temperature control, and supplemental controls.
AIR CHANGES PER HOUR (ACH)
As per the infectious disease control guidelines outlined by the Centers for Disease Control (CDC), isolation rooms should have a minimum of 12 air changes per hour using medical-grade HEPA filters. These filtration units are designed to remove 99.97% of airborne particles that are ≥0.3 µm in diameter. The American Institute of Architects (AIA) further specifies that a minimum of 12 air changes per hour are required for new facility constructions and renovations, while a minimum of six air changes per hour are required for existing facilities.
HVAC systems play a vital role in hospitals and other healthcare facilities. In addition to regulating airflow and maintaining comfortable temperature levels, they also help minimize the transmission of airborne diseases. When properly implemented, they can prevent the spread of contaminant-laden air through air purification, improved ventilation, and airflow control.
- Standard rooms do not require a specialized HVAC system.
- Negative pressure rooms require dedicated supply and exhaust systems separate from the building’s systems that do not permit any return air. A HEPA filtration should be connected to the supply system if the room will be used for isolating immunosuppressed patients. Additionally, the air conditioning system should be connected to an emergency power supply to prevent depressurization in the event of power loss.
- Positive pressure rooms can share an air system with the building as long as the minimum outdoor air requirements meet local requirements and restrictions. However, the supply air inlet should be fitted with a HEPA filter.
The recommended minimum differential pressure between the isolation room and adjacent rooms is 2.5 Pa (0.01” water gauge) for both negative and positive rooms.
Isolation rooms must be appropriately heated or cooled to maintain an average temperature of 75°F.
Ultraviolet germicidal irradiation can be used as a supplemental air-purifying measure.
ACHIEVING CONTAMINATION CONTROL WITH AIR INNOVATIONS
We offer a broad selection of products that help control contamination in healthcare facilities. For example, our IsolationAir® portable contamination systems can be used to turn standard-sized rooms into negative-pressure or positive-pressure isolation areas for patient care or containment in as little as 30 minutes. They quickly and easily create a sterile environment in an isolated space that prevents cross-contamination, ensuring patients and personnel are better protected against infectious diseases. IsolationAir systems have several key features:
- Pressure control to create a positive or negative pressure differential between the room and adjoining spaces
- HEPA filtration unit to capture and remove airborne contaminants
- UV-C sterilization unit to deactivate viruses and bacteria that have accumulated on the HEPA filter
- Heating/cooling to keep patients comfortable within the space
The system meets all the relevant guidelines outlined by the following organizations:
- Centers for Disease Control (CDC)
- American Institute of Architects (AIA)
- American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)
Download our IsolationAir brochure for more details about our line of standard hospital contamination control systems.
CONTACT US FOR YOUR ISOLATION ROOM ENVIRONMENTAL CONTROL NEEDS
In medical facilities, dedicated isolation rooms are a critical tool for controlling airborne disease transmission. These spaces can be expensive to build and often require extensive airflow control measures to prevent cross-contamination with the rest of the facility effectively.
At Air Innovations, we understand the importance of airborne disease control in the healthcare industry. Our CDC, AIA, and ASHRAE-compliant IsolationAir® contamination control systems help hospitals, extended care facilities, and emergency preparedness centers improve their surge response capabilities and infectious disease preparedness. The portable units can be quickly and conveniently deployed to convert standard rooms into isolated environments for a number of applications, saving healthcare facilities time and money.
To learn more about our environmental control solutions and how they can benefit healthcare facilities, contact us today.