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ASHRAE Publishes Standard 241, Control of Infectious Aerosols

July 8, 2023
It's official! The Society's "pioneering, consensus-based, code-enforceable standard" for buildings is now available for purchase.


ATLANTA (July 7, 2023) – ASHRAE has published its pioneering consensus-based, code-enforceable standard, developed to reduce the risk of infectious aerosol transmission in buildings.

ASHRAE Standard 241, Control of Infectious Aerosols can be purchased at

Standard 241 establishes minimum requirements to reduce the risk of airborne disease transmission, such as SARS-COV-2 virus, which causes COVID-19, the flu virus and other pathogens in buildings like single and multi-family homes, offices, schools and healthcare facilities. The standard applies to new and existing buildings and major renovations and provides requirements for many aspects of air system design, installation, operation and maintenance.

  • See ASHRAE leadership's recent comments on the new standard here.

Important topics addressed in the standard:

  • Infection Risk Management Mode (IRMM) – Establishes requirements for an infection risk management mode (IRMM), which applies during identified periods of elevated disease transmission risk. Authorities having jurisdiction can determine when the enhanced protections of Standard 241 are required. Resilience (the ability to respond to extreme circumstances outside normal conditions) in indoor air quality control design and operations is introduced;
  • Requirements for Equivalent Clean Airflow Rate – Sets requirements for equivalent clean airflow rate target per occupant of pathogen free air flow, reducing the risk of infection;
  • Requirements for Use of Filtration and Air Cleaning Technology  Provides extensive requirements for use of filtration and air cleaning (such as HEPA filters, air ionizers, or UV lights) to achieve equivalent clean airflow requirements and be cost effective effectively and safely;
  • Planning and Commissioning – Provides assessment and planning requirements for being ready for the times when there is an event with increased disease causing pathogen transmissions.  The standard has a building readiness plan, that documents procedures for assessing existing or new HVAC systems to determine if they are working properly and attributing to the equivalent clean air delivered to spaces.

For additional details or to purchase Standard 241 visit or contact ASHRAE Customer Contact Center at 1-800-527-4723 (United States and Canada), 404-636-8400 (worldwide) or fax 678-539-2129.


Founded in 1894, ASHRAE is a global professional society committed to serve humanity by advancing the arts and sciences of heating ventilation, air conditioning, refrigeration, and their allied fields. As an industry leader in research, standards writing, publishing, certification and continuing education, ASHRAE and its members are dedicated to promoting a healthy and sustainable built environment for all, through strategic partnerships with organizations in the HVAC&R community and across related industries.

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Media Contact

Karen Buckley Washington, Senior Public Relations Specialist, [email protected]