The ASHRAE Epidemic Task Force has released an updated, unequivocal statement on the airborne transmission of SARS-CoV-2 (the virus that causes COVID-19) in buildings.

It replaces the previous statement issued in April 2020 that said airborne transmission was “sufficiently likely” and that airborne precautions should be taken.

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

Epidemic Task Force chair William P. Bahnfleth, said 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 organisations that should be leading more strongly.

“ASHRAE volunteers have played a huge role in evaluating evidence and developing detailed guidance to improve indoor environmental quality,” Bahnfleth said.

“The public, globally, is benefitting from the volunteer efforts of some of the most knowledgeable scientists and engineers in our field and this updated guidance is proof of it.”

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

The statement comes as the US continues to struggle with the pandemic, despite the roll-out of vaccines. According to the Reuters COVID-19 tracker, 167,187,795 doses of COVID vaccines have been administered – enough to have vaccinated more than 25 per cent of the country’s population. But infections are also on the rise, with more than 65,000 still being reported each day.

Since the beginning of the pandemic, the World Health Organization (WHO) and the Centres for Diseases Control (CDC), have contended that transmission of SARS-CoV-2 was mostly by droplet and fomite modes, not airborne. More recently, both have acknowledged the risk of airborne transmission indoors.

Meanwhile the World Health Organisation (WHO) has released a roadmap to improve and ensure good indoor ventilation in the context of COVID-19.

It aims to define the key questions users should consider to assess indoor ventilation and the major steps needed to reach recommended ventilation levels or simply improve indoor air quality to reduce the risk of COVID-19.

It also includes recommendations on how to assess and measure the different parameters, specifically in health care, non-residential and residential settings whenever a person is under home care or home quarantine.

comments powered by Disqus