The introduction of ASHRAE 241 marks a significant advancement in how we evaluate indoor air cleaning technologies. While our previous post provided a comprehensive overview of the standard, we’ll dive deep into its groundbreaking testing protocol and why it matters for facility managers, building owners, and indoor air quality professionals.
The Problem with Traditional Testing Methods
Historically, manufacturers have tested air cleaning devices in surprisingly small chambers—often no larger than one cubic meter, essentially the size of a shoebox. This approach has led to a critical disconnect between laboratory results and real-world performance. Consider this: you could theoretically show significant pathogen reduction in such a tiny chamber using something as simple as a cigarette lighter—clearly, not a practical or valid solution for indoor air quality management!
ASHRAE 241’s Revolutionary Approach
The new standard addresses these limitations by mandating a testing chamber of 800 ft³ (22.7 m³), approximately the size of a typical office space. This dramatic increase in testing volume creates conditions that much more closely mirror real-world applications, providing more reliable and practical performance data.
Why MS2 Matters
A key component of the protocol is the use of MS2 bacteriophage as the test pathogen. This choice is significant for several reasons:
- Superior Challenge: MS2 is a non-enveloped virus, making it more difficult to eliminate than many common pathogens, including:
– Enveloped viruses (like SARS-CoV-2 and H1N1)
– Bacteria
– Fungi
- Safety and Practicality: While MS2 is harder to kill, it’s less contagious than viruses like SARS-CoV-2 or H1N1, making it safer for laboratory testing while still providing a rigorous effectiveness benchmark.
- Hierarchical Validation: Success in eliminating MS2 effectively demonstrates the capability against easier-to-kill pathogens, providing a comprehensive validation of air cleaning effectiveness.
Impact on the Industry
This standardized testing protocol represents a significant step forward for the indoor air quality industry. For the first time, buyers can make purchasing decisions based on comparable, real-world-relevant performance data. This transparency and standardization help ensure that investments in air cleaning technology deliver the expected results in actual building environments.
The ASHRAE 241 protocol isn’t just about testing—it’s about trust. By establishing these rigorous, standardized testing conditions, the industry now has a clear benchmark for evaluating air cleaning technologies, ultimately benefiting everyone who breathes indoor air.
This blog is a part of a series highlighting the details of 241, so make sure to check out the rest of the series. You can also visit – https://www.ashrae.org/technical-resources/bookstore/ashrae-standard-241-control-of-infectious-aerosols – to learn more and purchase the full standard.