"As an industry, we are doing remarkably few measurements and estimates of airborne concentrations of an airborne pathogen, especially when considering how infection rates are directly influenced by building air quality controls.”

Since the beginning of 2020, a tidal wave of guidance has been provided by industry organizations on how to operate buildings during the SARS-CoV-2 pandemic. What has been lacking is empirical evidence.

When it exists, empirical evidence is the result of scientific research conducted in controlled laboratory settings with intentionally few variables. While requisite for research, it often makes the application of results to complex real-world scenarios challenging or impossible. This is further exacerbated when data from research is contradictory.

As a result, the answer to a simple question: “How do I know if a building is safe, right now?” ends up being highly complex and full of uncertainty.

This is especially true of indoor air quality and the ongoing fear of airborne transmission. “How do I know if the air is safe, right now?” is one of the most critical yet difficult questions to answer.

Although it is currently impossible to measure airborne viruses in real-time, it is possible to measure a building’s ability to minimize the potential of infection from airborne (in particular aerosol) transmission, in real-time across a range of parameters. Doing so requires combining scientific research with real-time results in a standardized and meaningful way.

The key lies in focusing on air quality variables that can be controlled and measured in both laboratory and indoor environments; temperature, humidity, carbon dioxide (CO2) and airborne particles. From there, it is then possible to factor in the impact of measured air changes or air cleaning rates.

The results are powerful: enabling users to gain insight into a indoor space’s level of optimization based on a minimum of three or four indoor air quality metrics. As always however, the accuracy of the results are determined by the accuracy of the data being used: data quality is paramount.

Data Quality: Translating science into a real-time operational standard

Over the past decade, RESET has focused on defining data quality and accuracy for building operations. As a result, when reviewing scientific literature related to airborne transmission, RESET’s starting point was to identify variability between research results: a critical first step in defining uncertainty coming from scientific literature, to be added to levels of uncertainty collected from continuous monitoring.

Results were classified according to dominant research topics, inclusive of:

• Virus survivability
• Host’s immune system health (host)
• Dosage (quantity over time)
• Rates of transmission / infection

With research often being done in silos, results from the above topics only provide partial visibility on the environmental parameters driving or minimizing infection rates. Moreover, each research topic comes with its own level of uncertainty.

In order to translate these research topics into metrics applicable to building operations, the topics were organized into the following relational framework:

[Viral Survivability] + [Immune System Health] + [Dosage] = [Infection]

The above framework allowed for validation of the findings (inclusive of uncertainty) by comparing inputs on the left with outputs on the right. It also started to provide valuable insight into the contribution of each parameter to the risk of infection. Key findings will be published in a separate article.

Recognizing that viruses react differently to environmental parameters such as temperature and humidity, the above methodology was applied to Influenza, SARS-CoV-1 and SARS-CoV-2, as per available research studies.

Of 100+ research studies considered, 29 fit our research criteria and were incorporated into the development of the indicator. The contradiction in results from individual research studies led to the creation of a variability score, helping to transparently qualify the uncertainty in the final indicator. The results highlight opportunities for further research as well as the importance of having multiple researchers replicating a single study.

The work of compiling and comparing research studies by our team is ongoing and can be accessed upon request. It will be made public after further peer review, with the goal of creating a feedback loop between scientists and building operators.

The final results are being used to inform two indicators, as well as an uncertainty score, based on real-time data from indoor air quality monitors:

• Building Optimization Index: Previously focused on particulate matter, CO2, chemical off-gassing (VOCs), temperature and humidity, the RESET Index is being expanded to include infection potential into a building system’s overall level of optimization for human health.
• Airborne Infection Potential: Calculates a building’s contribution to the reduction of potential infection via airborne (aerosol) pathways.

The indices also provide building operators with a breakdown of impact on immune system health, virus survivability and exposure, all of which will provide insights into the outcome of operational decisions.

“The two indices will be added to the RESET Assessment Cloud, where they will continue to evolve,” says Anjanette Green, Director of Standards, “They won’t be required for certification, but will be available to users at no extra cost via API as a part of their analytics toolkit.”

To further refine the results of the indicators, additional parameters are being factored into the overall assessment. These include the impact of indoor air cleaning solutions, air changes measured in real-time, broad spectrum particle counting and real-time occupancy data.

The final Building Optimization Index and Airborne Infection Indicator is first being made available via RESET Accredited Data Providers for testing and refinement, prior to public release. If you are a building owner, operator, tenant or academic interested in being involved, please contact us.

“Eight years ago, particulate matter could only be measured by a handful of professionals: the average person had no way of knowing whether or not their building was optimized for safety,” says Raefer Wallis, Founder of RESET.” Now, building optimization for particulates can be measured by anyone, anywhere and at any time, over a range of sizes. We’re going to see the same thing happen with building optimization of airborne viral transmission, only much, much faster. RESET is helping building owners stay ahead of the curve.”

Update (2020.11.23)

Click here for a recording of the webinar or click here to learn more about the RESET Index.

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