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March 3, 2022

UL Verified Ventilation & Filtration, powered by SafeTraces

By Erik Malmstrom
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  • The lack of a measurable, verifiable ventilation and filtration standard for pathogen protection has been a longstanding public health gap, contributing to inconsistent application of controls, preventable infections, financial loss and waste, and a major public trust deficit in workplace safety.
  • In response, SafeTraces and UL are excited to launch the first ever assessment and rating program for real world ventilation and filtration performance for aerosol removal, inspired by addressing the defining public health risk of our times – airborne diseases spread via infectious aerosols.
  • The verification mark is awarded annually to buildings whose ventilation and filtration controls provide 99% hourly aerosol removal in high density areas based on a comprehensive desktop audit to verify equivalent air change rates (eACH) backed by field testing with aerosol-based diagnostic solution to directly, accurately verify that real world performance meets design specifications.
  • Our major impetus came from corporate, commercial, and institutional real estate owners/operators seeking to enhance, communicate, and differentiate on indoor air quality (IAQ), ventilation, and filtration with direct financial implications linked to health & safety, capex/opex, and sustainability.

Waiting for a Ventilation and Filtration Standard for Pathogen Protection…

“We need an eff’ing number,” an exasperated IAQ authority exclaimed to me in the summer of 2020.

He was referring to the longstanding need for a clear ventilation and filtration standard for aerosol removal, all the more urgent in the face of SARS-CoV-2, an unprecedented airborne pathogen spread via infectious aerosols and paralyzing the built environment from offices to schools to nursing homes to restaurants.

To those not close to the world of IAQ, it may come as a surprise that the US along with most countries do not have a measurable, verifiable standard governing ventilation and filtration controls for pathogen protection outside of healthcare facilities.

For context, how important is ventilation and filtration?

According to the National Institute of Occupational Safety and Health (NIOSH), inadequate ventilation is responsible for 52% of IAQ risk, including exposure to infectious aerosols, representing the single largest source of risk.[1]
Image source: The New York Times.The American Industrial Hygiene Association states, “Engineering controls that can keep infectious aerosols at very low levels indoors offer the greatest promise to protect non-healthcare workers and other vulnerable populations as we reopen our businesses and workplaces.”[2,3]

Yet nearly two years later, we are still waiting for a clear standard, with nothing imminent. Consistently, key regulatory and standards setting bodies have failed to go beyond providing squishy guidelines for ventilation and filtration for pathogen protection.

The consequence? Without a measurable, verifiable standard, ventilation and filtration performance isn’t measured and managed for pathogen protection, consistently or in many cases at all. The second order consequences? Preventable infections. Financial loss and waste. And a crisis in confidence, with polls indicating nearly 90% of the public lacks trust in workplace safety.[4]

Simply put, we cannot afford to wait any longer. With Omicron subsiding, mask mandates being lifted, and the public increasingly returning to buildings in 2022, a clear ventilation and filtration standard for pathogen protection is critical not only for future pandemic preparedness, but also for overall public health, safety, and wellness to ensure a consistent level of IAQ across buildings.

Meeting the Moment: UL Verified Ventilation and Filtration, powered by SafeTraces

In response, SafeTraces and UL, two independent safety science leaders, are excited to launch the first ever assessment and rating program for real world ventilation and filtration performance for aerosol removal in the built environment.[5]

We were compelled to answer the poignant call to action by Lidia Morawska, Joe Allen, William Bahnfleth, and 31 other leading experts who co-authored A Paradigm Shift to Combat Indoor Respiratory Infection: Building Ventilation Systems Must Get Much Better.[6]

In this clear-eyed article, they pinpointed the central problem at the heart of the public trust deficit regarding workplace safety –

“at present, members of the general public…have no means of knowing the conditions of the indoor spaces that they occupy and share with others.”[7]

One of their key proposed solutions? In the same way restaurants publicly display certificates for food hygiene in the interest of public health, buildings should publicly display “ventilation certificates” to drive transparency, accountability, and safety. And to strengthen public trust, confidence, and peace of mind.  

A profound and elegant idea. Needed now more than ever.

Formulating the Verification Target: The Precedent of Health Care Facilities

But how should such a standard be formulated, without becoming trapped in technical complexity and debates that have prevented a measurable, verifiable standard from coming to fruition to date?

Our best starting point was ANSI/ASHRAE/ASHE Standard 170-2017, Ventilation of Health Care Facilities, which defines ventilation system design requirements that provide environmental control.[8] As mentioned, health care facilities are unique in the built environment by designing performance standards with specific consideration for pathogen protection.

While our task was not as simple as cutting and pasting Standard 170-2017 to non-health care facilities, the overall framework is valuable, particularly its clarity around three critical elements:

  1. “The Where”: Not all facility areas are equal from a risk perspective; patient care areas are different from resident care areas; resident care areas are different from support areas  
  2. “The What”: Minimum total (equivalent) air changes are established as a focal unit of measurement for standard setting, a quantifiable rate of clean air delivered to specific facility areas
  3. “The Hows”: Minimum total changes can be achieved in a variety of ways (e.g., outdoor air ventilation, filter efficiencies, etc) varying by requirements and capabilities of specific facility areas

Quantifying the Verification Standard: > 99% Hourly Aerosol Removal in High Density Areas

As part of a rigorous technical review by an independent UL committee, along with extensive consultation with experts spanning infectious disease, public health, industrial hygiene, aerosol science, and mechanical engineering, we have carefully crafted our program’s verification standard with a strong grounding in peer-reviewed scientific research while consciously making it comprehensible to the general public:

Let’s briefly unpack the logic and significance of each component:

  1. Verified: buildings should be regularly verified against a measurable standard via desktop audits of equivalent air change rates (eACH) from ventilation and filtration controls and field testing to ensure real world performance meets design specifications using an aerosol-based methodology[9]
  2. Ventilation & Filtration: ventilation and filtration together represent the most effective, safest controls for airborne pathogens, and their application as controls can and should be tailored to specific facility areas as appropriate while staying anchored to a measurable, verifiable standard
  3. Aerosol: because airborne diseases transmit primarily via infectious aerosols, real world ventilation and filtration controls should be verified directly with an aerosol-based methodology for accuracy
  4. High Density Areas: areas with higher density, prolonged occupancy, and physical enclosures face greater exposure risk to airborne pathogens and merit greater attention than other building areas
  5. 99% Hourly Removal: a 99% hourly removal rate is linked approximately to a 5 eACH rate, recommended by leading authorities[10] and exceeding exposure risk reduction provided by administrative controls and personal protection equipment (PPE) including masking[11]
99% hourly aerosol removal is linked to an approximate 5 eACH rate, a performance target recommended by Harvard T.H. Chan School of Public Health.[12]

Not Just Another Verification Mark: Differentiating with Technology, Simplicity, and Clarity

The most fundamental and differentiated aspect of our program are embodied in #1, #3, and #5.

#1 and #3 establish the fundamental principle that real world ventilation and filtration systems should be regularly verified for the purpose of reducing occupational exposure to infectious aerosols. Historically, we have been unable to directly and accurately test this performance area due to toolbox limitations. However, with the support of the National Institutes of Health (NIH), SafeTraces has developed the first field diagnostic platform leveraging aerosol tracers that safely (FDA-Generally Recognized As Safe materials) simulate airborne pathogen mobility and exposure levels in order to directly verify real world ventilation and filtration controls and provide high-quality accurate performance data grounded in science.[13]

#5 advances a measurable, verifiable standard with a solid scientific basis linked to eACH rates similar to those governing health care facilities, but simplified in a way that the non-experts can clearly understand. The public can have trust, confidence, and peace of mind that “Verified” buildings will provide a strong level of protection recommended by leading authorities against future coronavirus variants, influenza, and other airborne diseases, critically important given the unevenness in vaccination rates and efficacy, the removal of mask mandates and the likely reluctance to return to them in the future, and the impracticality and infeasibility of social distancing in many buildings.

Taking these factors together, we now have the capability to measure real world system performance for mitigating an aerosol-based risk with an aerosol-based diagnostic solution. To date, this level of analytical rigor has only been possible via software modeling, a flawed, unwieldy, and expensive theoretical tool. SafeTraces has developed a better, faster, and cheaper solution that can be used directly in field environments, not models. Our technological breakthrough helps clearly and credibly communicate workplace safety to address the huge public trust deficit challenging employers, landlords, and others in the built environment.

Beyond COVID-19: Optimizing Health & Safety, Financial, and Sustainability ROI

While our rating and assessment program is fundamentally about enhancing and communicating environmental health and safety in the built environment, the motivation for real estate owners and operators to implement such a program is primarily financial.

Thus, what is the return on investment (ROI) of our program for customers?

  1. Reducing costs from absenteeism, shutdowns, and adverse impacts to productivity
  2. Enhancing leasing rates and asset values by competitively differentiating properties around health & wellness and credibly positioning IAQ, ventilation, and filtration as a marketable amenity
  3. Optimizing HVAC spend by reducing cost and energy penalties, reducing service and maintenance costs, and extending system useful life
  4. Reducing carbon emissions from HVAC operations
  5. Meeting evolving compliance and code requirements
  6. Reducing liability risk associated with airborne pathogens

Notably, the major impetus for our program came from corporate, commercial, and institutional real estate owners/operators seeking to enhance, communicate, and differentiate on IAQ, ventilation, and filtration with direct financial implications linked to health & safety, capex/opex, and sustainability.

Succeeding in the Next Normal: Learn More

We are deeply committed to meeting the defining global health challenge of our times, to supporting real owners and operators to succeed in the “next normal,” and to strengthening public trust, confidence, and peace of mind in the health and safety of everyday indoor spaces.  

To learn more about UL Verified Ventilation and Filtration, powered by SafeTraces and speak with a representative, contact us at