Standard 241

In July of 2023, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), published its pioneering consensus-based, code-enforceable Standard 241, Control of Infectious Aerosols. Developed to reduce the risk of infectious aerosol transmission in buildings, Standard 241 establishes minimum requirements to reduce transmission risk of airborne viruses such as SARS-COV-2, the flu virus and other pathogens.

The standard applies to a wide range of building types, including single and multi-family homes, offices, schools and healthcare facilities. It includes both new and existing buildings, as well as major renovations. Standard 241 specifies a wide range of criteria – including for both effectiveness and safety – that air purification devices must meet in order to be in compliance. CerroZone technology meets or exceeds all criteria in the standard, as outlined in the list below:

• Pg 11, Table 7-1: MERV 11+ removal efficiency 
• Pg 17, 9.1.7: Efficacy per fan speed 
• Pg 23, A1.2.1: Testing shall be completed by a third-party independent laboratory 
• Pg 23, A1.2.2 a: Chamber volume shall be at least 800 cubic feet 
• Pg 24, A1.3.2: Test with non-enveloped MS2 
• Pg 27, Table A-1: Formaldehyde safety 
• Pg 27, Table A-1: Ozone safety 
• Pg 27, Table A-1: Particulate matter count concentration safety 

More details on Standard 241

ASHRAE Standard 241 outlines a number of methods and technologies to prevent the spread of airborne pathogens in buildings, one of them being the use of air purification equipment. Some of the key components of the standard are outlined below. 

• Establishes a “Minimum Equivalent Clean Airflow Rate” which is required in the “breathing zone” for each occupiable space in a building in order to mitigate long-range transmission risk. The equivalent clean airflow requirements can be met by air cleaning technology, such as that provided by CerroZone, as well as other methods such as outdoor air ventilation.
• Defines an “Infection Risk Management Mode” (IRMM) which applies during periods when higher levels of infection risk mitigation are desired, or are required by authorities based on public health data.
• Requires the development of a Building Readiness Plan (BRP) to document the sequences of operations during IRRM. Standard 241 allows for temporary air cleaning systems, such as the CerroZone mobile and mini units, to be included in Building Readiness Plans for new buildings and major renovations.

For complete details on Standard 241, visit the ASHRAE website.