Six Steps Hospital Facilities Can Take to Reduce the Risk of Spreading Infectious Disease

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The coronavirus disease (COVID-19) outbreak, categorized as a pandemic by the World Health Organization (WHO), has global healthcare systems on high alert to protect their patient populations and workforces. The rapid spread of this novel virus, about which much is still unknown, demands heightened efforts by facilities managers.

I have a background in building services and have spent my career designing control systems for HVAC systems for hospitals.  As a critical aspect of minimizing the risk of infection among patients and staff, facility managers should work in tandem with hospital leadership and infectious disease specialists to help ensure the efficient and optimal operation of their systems’ HVAC systems.

Key considerations that warrant close attention include the maintenance of high volumes of air change rates throughout the facility; the maintenance of negative pressure in the Airborne Infection Isolation Room (AIIR) in relation to surrounding areas; protocols to control access to the AIIR; adjusting and monitoring relative humidity in the AIIR in keeping with current findings; air filtration and removal; and ensuring the safety of resilient power supplies.

So, what can healthcare facilities do?

The Centers for Disease Control and Prevention (CDC) provide guidance to help minimize the chance of exposure. This requires healthcare workers to closely follow their infection control protocols and rapidly triage and isolate patients with symptoms of COVID-19 or other respiratory infections. Patients should wear surgical masks until they are placed in a single occupancy Airborne Infection Isolation Room (AIIR). These rooms are designed and operated to ensure room pressure is kept at a negative pressure and to protect clinical staff, other patients and visitors from exposure to airborne infectious.

You can help ensure safe operations of your facility by monitoring and controlling six areas:

1. Maintain the correct air change rate
Although the virus is largely considered to be transmitted via droplet  it is still unclear on how long COVID-19 remains airborne. According to Cole and Cook’s (1998) research, ejected droplets can have diameters of 20-40µm which means they are heavy and will fall to surfaces. The air flow and exchange rate alone will not significantly impact transmission unless the environment causes evaporation, making the droplets aerosol.  According to ASHRE, precautions should be taken to ensure high volumes of air change rates are still maintained as defined in ASHRAE 170 in the table below.

2. Keep the pressure in a negative scale
This is important to help ensure airflow is going in the correct vector. The AIIR should be maintained at a negative pressure to its surrounding areas and must be continuously monitored and recorded. When compromised staff must be informed via local displays and/or notifications. Several cases of infection have occurred when the pressure has been reversed due to door openings.

3. Control the access into the AIIR
This also needs to be managed and controlled to help keep a record of who has had access into the room and to provide an air lock to maintain pressure. The control of patients entering the room is achieved by enabling a higher level of access control into the room. Using access control systems that provide access strictly to authorised people can help limit the amount of healthcare providers (HCP) exposed. Combined with a real-time location system, this can also be taken a level deeper to understand the exact trail of the HCP who entered the room and where they subsequently travelled. The air lock is also important to provide an ante room, where HCP apply their personal protective equipment (PPE). By making sure both doors are not open at the same time, the pressure regime isn’t impacted.

4. Control the temperature and humidity
The function of the HVAC is to provide comfortable conditions for patients, but these parameters also have an impact on both bacteria and virus growth and survival. A recent study found the role of absolute humidity in the transmission of COVID-19 has not yet been established, and their results suggest it will not necessarily lead to declines. ‘Engineering Perspective on The Environment of Care and Health Care-Associated Infections’ for ASHE also concluded that there is still insufficient evidence that temperature and relative humidity influence transmission.

However, studies have shown that increasing the mean relative humidity from 35% to 50% may accelerate the removal of infectious Influenza A Virus and help prevent or reduce infection. The AIIR should be provided with both temperature and relative humidity monitoring, but other areas of the hospitals will not have this level of monitoring. It is typical for humidity to be measured at a common exhaust from the area. However, with IoT sensors, it is now more widely available to provide room level monitoring of these parameters. This provides a more detailed analysis for facilities and infection control teams to identify areas where humidity might have an impact on bacteria (high humidity) or viruses (lower humidity).

5. Ensure suitable filtration and clean status
The particle size of these viruses is very small and suitable filtration is needed to ensure they are not moved from one area to another. The air from an AIIR should not be recirculated, but rather exhausted directly outdoors. Yet, filtration is still needed. High-Efficiency Particle Air (HEPA) filters are needed to remove the very small particles. The facilities team should ensure they are changing these filters as needed based on dirty status from sensors monitoring the pressure drop across the filter. ASHRAE also provides guidance to apply personnel safety procedures when changing filters. Depending on the types of organisms and other contaminants collected on the used media, a risk assessment should be carried out.

6. Provide resilient power supplies
The need to ensure these systems work continuously is critical for the safety of patients and staff. Having redundancy for systems is needed as defined by the UK’s Healthcare Technical Memorandum (HTM) 06-01: “Appropriate standby provision should be identified (for example connection to the essential power supply or uninterruptible power supplies) to enable continuity of supply should a mains power failure occur”.


For facilities that do not have enough AIIR’s, patients should be isolated in exam rooms with doors closed and moved to a facility that can accommodate them. Some healthcare facilities have triage rooms that can be mechanically changed into negative rooms when potential pandemic situations occur. This requires a well-engineered mechanical ventilation system. All monitoring and control principles previously mentioned need to be adopted. For those facilities that cannot adjust their mechanical systems, other engineering controls and interim safety measures should be applied. Where patients are placed in examination rooms awaiting transfer, the CDC recommends isolating them and ensuring the air from that room is not recirculated. It may need a temporary exhaust system to provide the negative pressure in this situation.

The response and measures that are taken must be carefully coordinated with HCP and the infection control team to help ensure all members of the hospital are working safely and to the correct measures. Training and education are important, so every member must know the impact of leaving a door open or not washing hands. In 2018, airborne isolation room air flow (EC.02.05.01 EP15) was the 11th most cited incidence by the Joint Commission. This is where technology can support healthcare facilities, by utilizing EcoStruxure™ for Healthcare facilities can help;

  • Ensure the correct operation of ventilation systems to achieve the needed air changes and pressure regime using EcoStruxure Building Operation
  • Provide critical alerts to facility and clinical staff when safety might be compromised through EcoStruxure Building Operation
  • Continuously record and analyse the performance of critical areas with EcoStruxure Building Advisor and plan for maintenance on filters
  • Manage access and movement of people through the facility using EcoStruxure Security Expert
  • Ensure power availability through digitized electrical distribution and uninterruptible power supplies with EcoStruxure Power

As health systems around the world take measures to control and isolate this disease, healthcare facilities can assist by ensuring proper operations and maintenance.


Additional Bibliographic Resources

  • ASHRAE 170 Ventilation. ASHRAE
  • Cole, E. C. & Cook, C. E. 1998 Characterisation of infectious aerosols in healthcare facilities: an aid to effective engineering controls and preventative strategies. Am. J. Infect. Control 26, 453 –464. (doi:10.1016/S0196-6553(98)70046-X)
  • Memarzadeh, F. The Environment of Care and Health Care-Associated Infections. An Engineering Perspective. 2011. American Society of Healthcare Engineers

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  • Mark Richards

    4 years ago

    Unfortunately HTM 04-01 deals with water supplies and not electrical services.
    Perhaps it should read HTM 06-01

    • Christopher Roberts

      4 years ago

      Mark you are correct and thank you for pointing out the error in referencing the HTM. It is the health Health Building Note (HBN) 04-01 Supplement 1 “Isolation facilities for infectious patients in acute settings” which also identifies the need for appropriate standby provision and needs to be followed along with HTM 06-01

  • Hal Sampson

    4 years ago

    A more recent study finds a strong inverse correlation between relative humidity and viral transmission:

    One theory is that, at lower ambient humidity levels, aerosol droplets containing virus dry out faster after expulsion, shrink, suspend in the air longer, and thus carry farther.

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