ASHRAE Standard 241, Control of Infectious Aerosols, establishes guidelines to reduce disease transmission through exposure to infectious aerosols in new and existing buildings. Implemented in the USA in 2023, this standard is likely to be adopted in New Zealand in the coming years.

Standard 241 breaks new ground by setting requirements for the equivalent clean airflow rate—the flow rate of pathogen-free air into occupied areas of a building. This rate has the same effect as the total of outdoor air, filtration of indoor air, and air disinfection by technologies such as germicidal ultraviolet light. This approach allows users of the standard flexibility to select combinations of technologies that best satisfy their economic constraints and energy use goals.

Infectious aerosols are microscopic particles that can carry pathogens and linger in the air, posing a risk when inhaled. Adhering to Standard 241 helps building owners and operators reduce exposure to pathogens like the SARS-CoV-2 virus responsible for COVID-19, influenza viruses, and other disease-causing agents. The standard includes requirements for air system design, installation, operation, and maintenance, ensuring healthier indoor environments and future-proofing against airborne diseases.