Airborne Infection Isolation Rooms

As a responsible healthcare facility, you are committed to the health and well-being of both patients and staff alike. While you may take pride in protecting your patients and employees by providing a safe and sanitary facility, there are other, less obvious, areas to consider such as airborne contaminates and the use of airborne infection isolation rooms (AIIR).

Research cited by the Center for Disease Control and Protection (CDC) reports that an estimated 2 million infections, 88,000 deaths, and $4.5 billion in excess healthcare costs can be attributed to healthcare associated infections each year.

Over time, mechanical systems become degraded which conversely affects the functionality of your AIIR. A few things that could contribute to a less effective AIIR over time are changes to HVAC system air balancing, worn or slipping fan belts, and degraded seals around door and wall openings. It is important to check your systems regularly to make sure the AIIR rooms they serve continue to meet the code-required air exchange rate as well as maintain the appropriate pressure differentials between the AIIR and adjoining spaces. While the requirements for AIIRs installed before 1994 are less stringent than present guidelines, it is good practice to update older HVAC systems to meet today’s standards to best combat the dangers of airborne infections such as TB and SARS.

A well-designed AIIR typically has a dedicated exhaust system that removes 100 percent of the room air to the outside. According to CDC recommendations, exhaust discharge should run through a HEPA filter or discharge through a stack arrangement on the roof that minimizes risk of infection to personnel on the roof. The CDC, the American Society for Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and the American Institute of Architects (AIA) all publish requirements for minimum total air change, minimum outside air supply and minimum pressure differentials to be monitored by a dedicated audible/visible alarm. If not properly installed, these alarms could malfunction when individuals enter or exit the room. To prevent false alarms from occurring, it is important to carefully plan for the location and control of these alarms using built-in delays to account for opening doors. An effective alarm system should also allow for switching between normal and negative pressure operation depending on the room’s use.

Consulting a professional engineer to properly design and maintain your airborne infection isolation rooms can help reduce the risk of infections to both patients and staff. It could also save you money by minimizing the amount of down time when your AIIR is not functioning properly and limiting the maintenance and repairs associated with system malfunctions.

To learn more about how you can help protect your patients and staff from the risks associated with airborne infection isolation rooms, please contact Jon Slagel, PE at or (717) 845-7654.

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