Fallout from the COVID-19 pandemic continues. For more than three years, institutional and commercial facilities have contended with raised expectations related to indoor air quality (IAQ) among occupants, visitors and the general public, and they have responded with changes to ventilation and air filtration systems and practices. Now maintenance and engineering managers have guidance on which to base future IAQ decisions.
ASHRAE recently issued an airborne infection risk mitigation standard for buildings, bringing numerous benefits to occupants and promoting healthier environments. ASHRAE Standard 241, Control of Infectious Aerosols, establishes minimum requirements to reduce the risk of disease transmission by exposure to infectious aerosols in new buildings, existing buildings, and major renovations.
Infectious aerosols are tiny, exhaled particles that can carry disease-causing pathogens and are so small that they can remain in the air for long periods of time and be inhaled. Use of this standard would reduce exposure to SARS-COV-2 virus, which causes COVID-19, influenza viruses and other pathogens. Standard 241 provides requirements for many aspects of air system design, installation, operation and maintenance.
Important aspects of the standard include:
Infection risk management mode. Requirements of Standard 241 apply during an infection risk management mode that applies during identified periods of elevated risk of disease transmission. Authorities having jurisdiction can determine when the enhanced protections of Standard 241 will be required, but its use can also be at the discretion of the owner or operator at other times, for example, during influenza season. This aspect of Standard 241 introduces the concept of resilience – ability to respond to extreme circumstances outside normal conditions – into the realm of indoor air quality control design and operation.
Requirements for filtration and air cleaning technology. Dilution of indoor air contaminants by ventilation with outdoor air can be an energy intensive and expensive way to control indoor air quality. Standard 241 provides extensive requirements for use of filtration and air cleaning to effectively and safely achieve meet equivalent clean airflow requirements efficiently and cost effectively.
Planning and commissioning. Standard 241 provides assessment and planning requirements culminating in the development of a building readiness plan, a concept carried over from the work of the ASHRAE epidemic task force. It also describes procedures for commissioning systems to determine their installed performance.
Dan Hounsell is senior editor of the facilities market. He has more than 30 years of experience writing about facilities maintenance, engineering and management.
