ASHRAE: Changes in HVAC, building ops can reduce airborne transmission of COVID

Marianne Wilson
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The operation of HVAC systems can play a critical role in stopping the indoor spread of COVID-19.

 ASHRAE has released an updated — and its most unequivocal statement yet  — on the airborne transmission of SARS-CoV-2 (COVID-19) in buildings.

“Airborne transmission of SARS-CoV-2 is significant and should be controlled,” stated the ASHRAE Epidemic Task Force. "Changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures."

The new statement replaces the group’s April 2020 statement, which said that airborne transmission was “sufficiently likely” that airborne precautions should be taken. At that time both, the World Health Organization and the Centers for Diseases Control contended that transmission of SARS-CoV2 was by droplet and fomite modes, not airborne. Subsequently, both have acknowledged the risk of airborne transmission indoors.

“This may seem like a small step, but we feel it is important to leave no doubt about our position, given the muted support for ventilation and filtration as important tools in the effort to stop the pandemic, from some organizations that should be leading more strongly,” said William P. Bahnfleth, Ph.D., P.E., ASHRAE Epidemic Task Force chair.

The ASHRAE Epidemic Task Force has been developing and disseminating guidance for the control of airborne transmission of SARS-CoV-2 since its formation in March 2020.

To view the complete airborne transmission statement and other COVID-19 resources, visit