How Hospital Environments Could Potentially Impact Virus Risk

    When a hospital treats a patient with an infectious disease, the first concern is the patient’s health. The second is containing the disease so that it doesn’t spread to other patients or health care workers. The most obvious weapons in this fight are rigorous sanitization practices and personal protection equipment like disposable gloves, masks and gowns that health care workers use when treating patients.

    Viruses don’t limit themselves to surfaces; common illnesses, like influenza, measles and chickenpox, can be spread by airborne transmission. In these cases, the Centers for Disease Control and Prevention recommends that infectious patients be placed in an isolation room. The intent of an isolation room is to stop the spread. 

    Meeting High Standards

    The guidelines for management and construction of isolation rooms are specific, especially when it comes to controlling air flow into and out of the room. Phoenix Controls’ David Rausch, works with hospitals to make sure their HVAC systems are operating properly. “The CDC makes the standards clear and easy to follow,” says Rausch. “The hospital just has to look under the ceiling tiles and say, can we do this?”

    An Airborne Infection Isolation (AII) space requires a minimum negative pressure of 0.01 in Inches in Water Column (WC) and 12 Air Changes per Hour (ACH). This negative pressure needs to be monitored constantly while the space is occupied. “Good directional air flow, that’s key.” says Rausch. “Pull the bad air out, away from the staff and other patients, so it can’t infect anyone inside.”

    Nearly every hospital has an adjustable HVAC system to manage air flow, but Rausch says many hospitals have aging mechanical infrastructure that is already taxed and its struggling to consistently manage airflow. “The standard equipment works broadly, but it overshoots and undershoots until it finds the right air flow management.” Rausch says that becomes a problem in isolation rooms. “That back and forth to find the right setting compromises the isolation guidelines.”

    Quietly Exceeding Standards

    Seeking to maintain or exceed guidelines, many hospitals have adopted the Venturi valve by Phoenix Controls. “The valve stabilizes directional flow and maintains exhaust, tracking the supply to guarantee directional flow,” says Rausch. “It's a much more reliable technology that helps to maintain a space for these types of situation guaranteed, all the time.”

    In one study, when a Phoenix Venturi valve was tested and compared to a typical VAV Box system, the Venturi was more responsive and effective in reducing airborne particulate in an ICU patient room.1 The stable, directional flow produced by the Phoenix Controls Venturi valve, purged the space more efficiently which ultimately can reduce a hospital’s infection risk for that space.

    The Next 10 Years

    Hospitals have significant clinical and patient data – and so does the physical building. In the future, it will be about pairing the building data and insights with clinical data to help improve patient outcomes and experience. “Healthcare facilities are advancing from a quality of care standpoint, but often the buildings have been forgotten.” says Rausch, but he sees big changes ahead.

    “Sensing, monitoring and analytics are coming on board more and they’re being examined in clinical care routine. The building and the clinicians have been separate entities, they’ll be integrated more in the future, working together.”

    Phoenix Controls is a wholly owned company of Honeywell International.


    1.     The Center for Health Design, Analyzing ICU Patient Room Environmental Quality Through Unoccupied, Normal, and Emergency Procedure Modes: An EQI Evaluation, 2019