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The Role of Advanced HVAC Ventilation in Mitigating Airborne Transmission in the Post-COVID Era


By now, everybody knows that wearing masks, social distancing, and frequent use of hand sanitizer helps prevent the transmission of COVID-19 and other contagious diseases. But most people don't give a lot of thought to their HVAC systems, which can both spread and help stem the circulation of airborne pathogens — depending on the system and how well it's working.

HVAC stands for heating, ventilation, and air conditioning. State-of-the-art HVAC systems have become integral in safeguarding indoor environments against airborne pathogens in the aftermath of the COVID-19 pandemic.

Why? Poor ventilation not only fails to prevent disease; it can actually disseminate infectious agents through the system, worsening patients' symptoms at healthcare facilities and assisted living communities — which is the last thing you want to happen to people who are elderly or immune-compromised.


How Pressure Makes the Difference

In care facilities, residents' rooms must be pressurized either positively or negatively in relation to adjacent rooms. This pressure ensures that each space has properly conditioned air, is free of odors, and is environmentally controlled for bacteria, viruses, and other microorganisms.

How does it work?

  • Negative pressure removes contaminants to the outside to prevent cross-contamination

  • Positive pressure supplies more fresh air than what is removed.

Optimizing Air Flow and Filtration

The number of air changes per hour is also critical. Air changes per hour (ACH) refers to the amount of air that can be added to or removed from a space within an hour's time. When all of the air in the room has been completely recycled, that is one air change.

The Centers for Disease Control and Prevention (CDC) recommends that hospital patient rooms have at least six total air changes per hour and a minimum of two air changes per hour of outside air.

Clearly, this requires a highly efficient and effective HVAC system.

Air filtration obviously matters, but must be increased prudently, as the existing system needs to be able to handle an upgrade. Consider the highest filtration possible that will not result in a loss in pressure, which would reduce airflow and thus be detrimental to the HVAC system's overall benefit. If the airflow decreases, ventilation may become inadequate, and the system's cooling and heating ability will be taxed.

Questions to Evaluate Your Current HVAC System

Below are some key questions facilities managers should ask when evaluating their HVAC system's functioning and upgrade capacity:

  • How does air flow through the building? What are the pressure relationships between zones?

  • What filtration systems are in place? What are their efficiencies?

  • Is there obvious air infiltration? Is it localized?

  • Does the system provide adequate ventilation, given the building's occupancy and functions?

  • What is the condition of the mechanical equipment?

  • Are all dampers (outdoor air, return air, bypass, fire, and smoke) functioning? Are they sealed well when closed?

As we know after dealing with COVID and its many mutations over the past three and a half years, the SARS-COVID virus can remain airborne indoors for many hours and potentially increase in concentration over this period of time. We've learned that without adequate precautions, the longer a space is occupied and the more people that are present, the greater the potential for airborne transmission of the virus.

So aside from avoiding large gatherings and keeping residents who feel unwell restricted to their rooms until they test negative for COVID, maintaining a state-of-the-art HVAC system is one of the best ways to ensure the people in your care will be breathing air that is as healthy as possible, and designed to keep them that way as well.


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