An isolation room controls the airflow so that the number of airborne infectious particles is minimized make the risk of cross-infection of other people within a healthcare facility highly unlikely.

This may be achieved by controlling the quantity and quality of intake or exhaust air, maintaining different air pressures between neighboring areas, designing airflow patterns for specific clinical procedures, diluting infectious particles with large air volumes, and air filtration. Isolation rooms are frequently used in hospitals and other healthcare facilities, where controlling the spread of infectious diseases is essential to keep patients, personnel, and visitors safe and healthy.

Isolation rooms don’t always require an anteroom. This requirement should be determined by the proposed operational policy and be included at an early stage of the design process.

When an anteroom is required, it must have self-closing doors and sufficient area to allow for the donning or removing personal protective equipment (PPE).

An assessment of the service requirements of the hospital isolation room should be made to determine the practicality of sealing junctions at penetrations to ceiling and wall linings.

In some instances, the number of service penetrations in partitions and ceilings may suggest introducing a false wall or additional partition. The false wall provides a way of finding service points while preserving the integrity of differential air pressures because of the room’s external lining not being penetrated.

This article explains some of the requirements for building hospital isolation rooms and the considerations that should be made.

Room Requirements

Individual control and equipment decisions come together in the designs of the negative and positive pressure rooms themselves. A negative-pressure room is intended to isolate a suspected patient or has been diagnosed with an airborne infectious disease. Therefore, the negative-pressure isolation room is designed to help stop an infection from spreading from an infected patient to others in the hospital.

When there is an anteroom, airflow should be from the corridor into the anteroom, and the anteroom into the patient’s isolation room. The exhaust air quantity should always be higher than the supply airflow to maintain the required pressure differential.

Exhaust from negative-pressure isolation rooms must be expelled directly outdoors without mixing. However, multiple aII isolation rooms can be connected to the same exhaust system. The exhaust ductwork serving the rooms must also be permanently labeled as contaminated air.

Supply air for the room is generally found in the ceiling at the base of the patient’s bed, with exhaust air taken from exhaust grilles situated right above the patient’s bed on the ceiling or low on the wall near the head of the bed. When the head wall exhaust grilles are lower than seven feet above the floor, NFPA 90A necessitates the protection of the opening by a grille or screen through which a half-inch sphere cannot pass.

A positive-pressure isolation room is meant to keep contagious diseases away from patients with compromised immune systems. They require a minimum of 12 air changes per hour of supply air. They must maintain a minimum 0.01-inch WC positive-pressure differential to ensure that the patient is protected from airborne contamination whether or not an anteroom is used.

Supply air for the room must be situated in the ceiling above the patient’s bed, with return air taken from the ceiling near the door. The supply diffuser should be a non-aspirating, laminar-flow device. It should be designed to limit the air velocity at the patient’s bed to decrease the possibility of patient discomfort. ASHRAE 170 necessitates airflow to the PE isolation room be maintained at a constant volume to provide consistent ventilation in the room.

Considerations

Hospital isolation rooms must be designed and constructed carefully, or else there is an increased risk of cross-contamination between personnel, patients, and visitors. While there are many considerations to ensure an isolation room will work adequately, some of the most important include air changes per hour, HVAC, pressure control, supplemental controls, and temperature control.

As per the guidelines outlined by the Centers for Disease Control, isolation rooms should have at least 12 air changes per hour using medical-grade HEPA filters. These filtration units remove 99.9 percent of airborne particles that are greater than 0.3 µm in diameter. The American Institute of Architects also specifies that a minimum of 12 air changes per hour are needed for new facility constructions and renovations. In comparison, a minimum of six air changes per hour is required for existing facilities.

HVAC systems play a crucial role in hospital isolation rooms. While they regulate airflow and maintain comfortable temperature levels, they also help minimize airborne disease transmission. When properly implemented, they can stop the spread of contaminant-laden air through air purification, improved ventilation, and airflow control.

Negative pressure rooms must have dedicated supply and exhaust systems separate from the building’s systems that do not allow any air to return to the room. A HEPA filtration should be attached to the supply system if the room is used to isolate immunosuppressed patients. The air conditioning system should also 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 degrees F. Ultraviolet germicidal irradiation can be used as a supplemental air-purifying measure.