June 29, 2023

ASHRAE Approves Standard on Controls for Infectious Aerosols in Indoor Spaces

ASHRAE has approved for publication a new standard intended to reduce the risk of transmission of COVID-19, influenza, and other airborne diseases in indoor spaces. ASHRAE Standard 241, Control of Infectious Aerosols, includes requirements for air cleaning system design, installation, commissioning, operation, and maintenance. According to the organization’s press release, Standard 241 differs from other indoor air quality standards in that it sets requirements for equivalent clean airflow rate, which ASHRAE describes as “the flow rate of pathogen free air flow into occupied areas of a building that would have the same effect as the total of outdoor air, filtration of indoor air, and air disinfection by technologies such as germicidal ultraviolet light.” Other aspects of the standard address how to use filtration and air cleaning to meet equivalent clean airflow requirements safely, efficiently, and cost effectively.

Standard 241 was not developed under rules approved by the American National Standards Institute (ANSI) because ASHRAE wanted to make it available for use as soon as possible. ASHRAE had set a goal to finalize the standard within six months when the organization announced the project in December 2022. The draft standard was produced in 10 weeks and was available for public review and comment from May 12 to May 26, 2023.

Now that the standard has been approved for publication, ASHRAE says the Standard 241 committee will focus on clarifying requirements of the standard and developing tools to help the public use it. The organization intends to make related courses, podcasts, fact sheets, and additional information available in the future.

Further details about the new standard can be found in ASHRAE’s news release.