Air Quality Matters

This week, we step slightly outside the building envelope to examine a question that fundamentally challenges everything we think we know about air pollution: What if the metric the entire world uses to measure air quality is structurally blind to the most dangerous particles we breathe?

The document is a perspective piece published in the Bulletin of the World Health Organization, titled Air Quality Standards and WHO Guidance on Particulate Matter Measurement 2.5 Microns. It represents a profound wake-up call for the global air quality community, arguing that PM 2.5—the gold standard metric used worldwide to regulate, monitor, and discuss particulate air pollution—has serious fundamental blind spots that could be undermining decades of public health policy.

The World Health Organization's normative guidance on ambient air quality is fundamentally based on evidence from health and exposure studies regarding the harms associated with mass concentrations of airborne particulate matter expressed as PM 2.5. These WHO guidelines are a critical reference point for jurisdictions all over the planet when developing or revising their own ambient air quality standards. But this paper makes a stark argument: our global gold standard is missing the full scope of health-harming particulate air pollution.

Key Topics Discussed:

The Harmonization Problem: The current WHO guidance does not cover harmonization of averaging methods for concentrations measured during data aggregation, nor does it cover how to handle exceedances of PM 2.5 levels. Variations in how different countries measure and aggregate data can obscure true ambient air pollution levels—comparing apples with oranges on a global scale.

The Mass-Based Metric is Fundamentally Flawed: PM 2.5 is a mass-based metric. It simply weighs the dust. It completely fails to consider the physicochemical characteristics of airborne particles—their specific size, chemical composition, bioavailability of potentially harmful elements, and critically, the particle number concentrations of different sized particles, including ultrafine particles.

The Bowling Ball vs. Marbles Problem: Imagine a box. A single bowling ball gives you a high weight reading. But what if that box is filled with tens of thousands of marbles? The mass of PM 2.5 comes mostly from larger fine particles. The mass of ultrafine particles is negligible when compared to bigger particles. However, the vast majority of particles in typical ambient environments are ultrafine particles—defined as being less than 0.1 microns. A city could hit its WHO mass targets by removing a few heavy bowling balls but leave tens of thousands of smaller marbles floating around.

The 5 Microgram Threshold: When PM 2.5 is higher than 5 micrograms per cubic meter, the mass concentration does not correlate well with the particle number of ultrafine particles. Therefore, control measures that aim to reduce high PM 2.5 levels might not actually reduce the ultrafine particle count at all. A good correlation does exist below 5 micrograms per cubic meter, but as the authors bluntly state, most countries are far from achieving such low ambient air pollution.

Why Ultrafine Particles Are So Dangerous: Because they are so small, they don't just get stuck in your throat or upper airways—they go deep. Short-term exposure is associated with respiratory symptoms and systemic inflammation, affecting your heart and blood pressure. Long-term exposure is associated with increased mortality, especially cardiovascular and lung-related mortality, as well as ischemic heart disease.

Air Quality Standards and WHO Guidance on Particulate Matter Measurement 2.5 Microns

Bulletin of the World Health Organization 10.2471/BLT.23.290522 (https://doi.org/10.2471/BLT.23.290522)

The One Take Podcast in Partnership with

SafeTraces (https://www.safetraces.com/) and Inbiot (https://www.inbiot.es/?utm_campaign=simon&utm_source=airqualitymatters&utm_medium=podcast)

Do check them out in the links and on the Air Quality Matters Website (https://www.airqualitymatters.net/podcast)

Chapters

00:00:00 Introduction: The Blind Spot in Our Global Air Quality Standard
00:01:49 The Structural Problem: Missing Harmonization in WHO Guidance
00:02:45 The Fundamental Flaw: Why Mass-Based Metrics Miss the Point
00:03:49 The Bowling Ball vs Marbles Problem: Understanding Particle Count
00:05:14 The Five Microgram Threshold: Where Mass and Number Diverge
00:06:18 The Health Threat: Why Ultrafine Particles Are So Dangerous
00:07:13 The Solution: Introducing PM 2.5 Number Density Metric
00:08:33 The Practical Challenges: Monitoring Ultrafine Particles in the Real World
00:09:32 The Indoor Air Quality Wake-Up Call: What Your Monitors Are Missing
00:11:20 The Path Forward: Harmonizing Global Standards for Real Protection

This week, we sit down with Jason Jones, Director of Air Quality Management at Fellowes, to explore a question that fundamentally challenges how we sell, specify, and sustain indoor air quality solutions in the real world: What if the biggest barrier to clean indoor air isn't technology or science—but the economic conversation we're having with the people who actually have to write the cheques?

Jason leads Fellowes' sales and marketing efforts in the air quality space, working closely with distributors, sales representatives, and end users to help them understand the role of smart, responsive air quality management. This is a theory into practice conversation, and it's critically important. We can discuss the impacts of air quality on health, wellbeing, performance, and energy all day long—but at some point, someone, somewhere, has to literally buy into the idea. Jason provides a fascinating window into how a respected player in the sector, delivering products that actually improve air quality, frames the problem and the solutions, how those conversations are going, and where they think this sector is heading next.

Key Topics Discussed:

Post-Pandemic Reality: How air quality awareness has evolved since COVID. Some people internalized the lesson and carried it forward into the environments they work in. Others were willing to just get back to normal. The perception problem: if it doesn't smell bad, chances are the air must be clean. But we don't get to control the air we breathe in most of the spaces we're in.

Where the Traction Is: Healthcare, education, K-12, higher ed, and assisted living facilities are where air quality is sticking most. The generation that missed prom because of the pandemic took that lesson forward into their lives. That's why there's a bright future for air quality—it made an indelible mark on that generation.

Leaning Into Energy Savings: Why Fellowes is talking more and more about energy savings and using standards like ASHRAE's Indoor Air Quality Procedure to specify air purification alongside HVAC systems. The goal: reach the same or better air quality while reducing outside air reliance. Clean air is a human right, but the reality is that building owners have bills to pay and balance sheets to worry about.

VRP vs IAQP—A 101: Ventilation Rate Procedure is the blunt instrument—prescriptive ventilation rates based on building type and occupancy. Indoor Air Quality Procedure is more sophisticated—designing around specific contaminants of concern, factoring in air purification and filtration, and allowing you to reduce outside air by 30, 40, 50 percent or more. Less outside air means less heating and cooling, smaller HVAC systems, and potential first cost savings.

The Education Experiment: Schools are a massive data set. With thousands of classrooms being phased into air quality solutions over time, we'll finally be able to see clear trends in absenteeism rates, teacher sick days, and student test scores. You can't learn if you're not in class. It's that simple. And it's the most black and white metric of them all.

GUEST:

Jason Jones https://www.linkedin.com/in/jason-jones-0aa672b/

Director of Air Quality Management, Fellowes

Fellowes https://www.fellowes.com/

The Air Quality Matters Podcast in Partnership with

Particles Plus https://particlesplus.com/

Farmwood (https://farmwood.co.uk/) - Eurovent (https://www.eurovent.eu/) - Aico (https://www.aico.co.uk/) - Ultra Protect (https://www.ultra-protect.co.uk/air-quality-matters)

The One Take Podcast in Partnership with

SafeTraces (https://www.safetraces.com/) and Inbiot (https://www.inbiot.es/?utm_campaign=simon&utm_source=airqualitymatters&utm_medium=podcast)

Do check them out in the links and on the Air Quality Matters Website. (https://www.airqualitymatters.net/podcast)

If you haven't checked out the YouTube channel its here (https://www.youtube.com/@airqualitymatters-SimonJones). Do subscribe if you can, lots more content is coming soon.

Chapters

00:00:00 Introduction: The Commercial Reality of Indoor Air Quality
00:03:11 Post-Pandemic Reality: Who Still Cares About Air Quality?
00:08:09 The Budget Battle: Nice to Have vs Need to Have
00:10:05 The Energy Efficiency Angle: A New Way to Sell Clean Air
00:26:00 VRP vs IAQP: Two Approaches to Building Ventilation
00:24:47 The HVAC Energy Equation: Why Outside Air Is So Expensive
00:34:18 The Complexity Challenge: Is the Industry Ready for IAQP?
00:37:51 The Subjective Element: Why Human Perception Still Matters
01:25:09 The Fellows Ecosystem: Networked Air Quality Management
01:16:44 Education as the Testing Ground: The Data Goldmine
01:41:28 The AI Revolution: Natural Language Control of Building Systems

This week, we examine a document that represents a profound shift in how we think about school environments: What if the debate over airborne transmission and clean air in schools is finally over—and the real fight is just beginning?

The document is titled Ventilation and Air Quality in Education and Childcare Settings, published on 24 February 2026 by the UK Department for Education. It applies specifically to England, and it codifies into official government guidance something we've been arguing about for years: that good ventilation is absolutely essential for healthy and productive learning environments. This isn't a theoretical discussion anymore. This is operational policy.

The guidance plainly states that effective ventilation does more than just prevent overheating. It improves pupils' alertness and concentration. It removes polluted air. And crucially, it removes air that might contain virus particles, reducing the spread of respiratory infections like colds, flu, and COVID-19. This is massive. It places the management of indoor air quality squarely in the realm of basic school health and safety.

Key Topics Discussed:

The Monitoring Framework: Schools are expected to regularly monitor CO2 concentrations across their buildings. The guidance provides best practices on sensor placement—at head height or table height, at least half a meter away from people, and away from doors, windows, or ventilation outlets. If you're under 800 ppm, your ventilation is good. Between 800 and 1500 ppm, it's adequate but could be improved. Over 1500 ppm, your ventilation is officially poor and you need to act.

Pragmatic Winter Compromises: The guidance addresses the real-world conflict between keeping kids warm and keeping their air clean. Partially open windows, open higher-level windows to reduce drafts, air out rooms for 10 minutes every hour during breaks. But crucially, do not prop fire doors open to get cross ventilation.

Beyond CO2: The document talks about multifunctional environmental sensors that can track temperature, humidity, particulate matter like PM2.5 and PM10, and volatile organic compounds from sources like formaldehyde, cleaning chemicals, body odors, and vaping products. Yes, they specifically mention monitoring for vapes.

Air Cleaning Units—With Massive Caveats: The Department for Education is crystal clear that while air cleaning units reduce airborne contaminants including viruses, bacteria, and fungal spores, they do absolutely nothing to improve ventilation or lower CO2 levels. They are not a substitute for ventilation. The government only recommends HEPA filtration units—subtractive technology that physically catches pollutants. They explicitly reject air ionizers, ozone generators, and units with unenclosed UV fields.

The Funding Sting: Between 2021 and 2023, the Department for Education provided CO2 monitors and air cleaning units to all state-funded education settings. But now, in 2026, the guidance explicitly states that the government will not replace faulty or damaged devices, and they will not pay for replacement filters. The ongoing financial burden of maintaining clean air has been shifted entirely onto individual school budgets.

The Controversial Bits: The guidance talks about bringing in fresh outdoor air—a phrase doing a lot of heavy lifting when many schools are backed up against busy roads. It standardizes on NDIR CO2 sensors, which are solid but arguably already behind the times compared to photoacoustic sensors. And that 1500 ppm threshold—many in our community will argue that allowing CO2 levels anywhere near 1500 ppm is simply not acceptable for vulnerable populations.

Ventilation and Air Quality in Education and Childcare Settings UK Department for Education, 24 February 2026

https://www.gov.uk/government/publications/ventilation-and-air-quality-in-education-and-childcare-settings/ventilation-and-air-quality-in-education-and-childcare-settings

The One Take Podcast in Partnership with

SafeTraces (https://www.safetraces.com/) and Inbiot (https://www.inbiot.es/?utm_campaign=simon&utm_source=airqualitymatters&utm_medium=podcast)

Do check them out in the links and on the Air Quality Matters Website (https://www.airqualitymatters.net/podcast)

Chapters

00:00:00 Introduction: The UK's New School Air Quality Guidance
00:01:15 The Science Is Settled: Air Quality as Basic Health and Safety
00:02:16 The Monitoring Solution: CO2 as Your Ventilation Indicator
00:03:19 The Traffic Light System: Understanding CO2 Thresholds
00:04:03 Winter Pragmatism: Balancing Warmth and Fresh Air
00:04:46 Beyond CO2: Multifunctional Environmental Sensors
00:05:36 Air Cleaning Units: The Promise and the Limitations
00:06:39 HEPA Only: The Government's Firm Stance on Technology
00:07:41 The Sting in the Tail: Who Pays for Ongoing Maintenance
00:08:56 The Uncomfortable Details: Fresh Air, NDIR, and 1500 PPM
00:10:41 The Bottom Line: Science Won, Now the Funding Battle Begins

This week, we sit down with Stephanie Taylor, a unique physician architect whose career is dedicated to bridging the deep chasm between the medical profession and the built environment, to explore a question that fundamentally challenges how we think about buildings: What if the real problem isn't just that our buildings are failing us—but that we're measuring the wrong things entirely?

As medical advisor for ThinkLite Air, she applies her clinical insights to the development of advanced air sensing and cleaning technology, transforming raw environmental data into actionable health impact scores. By integrating medical science into engineering standards, she continues to champion the idea that engineers are in many ways the physicians of the future, responsible for the preventative care of billions of people who spend so much of their time indoors.

Key Topics Discussed:

Buildings as Extensions of Health: Why treating buildings as part of caring for human health could be one of the biggest advances of our century. The opportunities are clear: decreased acute and chronic diseases, improved productivity, better financial outcomes. But will we actually do it? The obstacles include resistance to change, difficulty bringing the medical community into building management, and the legal ramifications of talking about health.

Defining the Finish Line: What does good indoor environmental health actually look like? Stephanie's answer: an indoor space that does not increase our physiological stress level. Not just measuring hazards, but diminishing components of the indoor environment that cause stress on our cardiovascular, respiratory, neurological, and immune systems.

The Imperceptible Forces Problem: We design buildings and respond to environments as we can perceive them—rain, cold, visible mould. But the imperceptible exposures are the ones causing us problems. Low humidity impairing immunity. Ultrafine particles penetrating deep into the lungs. VOCs we cannot smell. The challenge is monitoring and controlling what we cannot sense.

The Platinum Building Paradox: Why even the most advanced buildings with all the badges can fail spectacularly. A healthy buildings conference held in a room where 100 experts sat in a fog of their own breath for four hours, CO2 climbing to 3,000 parts per million in one of the smartest buildings in London. The disconnect between design intent and operational reality.

Beyond Wells Riley: Rethinking how we model risk. The traditional Wells Riley equation models exposure to infectious bioaerosols. Stephanie is expanding that framework to model not only exposure risk, but also what indoor air quality is doing to your immune system—your protective mechanisms. It's not just how many weapons are shooting at you, but your ability to defend yourself.

ThinkLite and the Health Index: Seeing what's going on through sensors, analyzing the data in a way that is relevant for the human body system by system—lungs, brain, cardiovascular health—and then remediating. Turning arbitrary data points into relevant health metrics. Moving from zigzag lines on dashboards to actionable health impact scores

GUEST:

Stephanie Taylor

Physician Architect | ASHRAE Fellow | Medical Advisor, ThinkLite Air

Stephanie Taylor - LinkedIn https://www.linkedin.com/in/stephanie-taylor-md-b6456b8/

https://www.thinkliteair.com/

The Air Quality Matters Podcast in Partnership with

Particles Plus https://particlesplus.com/

Farmwood (https://farmwood.co.uk/) - Eurovent (https://www.eurovent.eu/) - Aico (https://www.aico.co.uk/) - Ultra Protect (https://www.ultra-protect.co.uk/air-quality-matters)

The One Take Podcast in Partnership with

SafeTraces (https://www.safetraces.com/) and Inbiot (https://www.inbiot.es/?utm_campaign=simon&utm_source=airqualitymatters&utm_medium=podcast)

Do check them out in the links and on the Air Quality Matters Website. (https://www.airqualitymatters.net/podcast)

If you haven't checked out the YouTube channel its here (https://www.youtube.com/@airqualitymatters-SimonJones). Do subscribe if you can, lots more content is coming soon.

Chapters

00:00:00 Introduction: Buildings as an Extension of Human Health
00:06:42 The Medical-Building Disconnect: Why Healthcare Must Join the Conversation
00:12:17 Defining the Finish Line: What Does a Healthy Building Actually Look Like?
00:23:29 The Imperceptible Hazards: Why We Design for What We Can Sense
00:27:38 The Autonomic Building: Automation as an Extension of Human Physiology
00:33:27 The Platinum Building Paradox: When Award-Winning Spaces Fail Their Occupants
01:01:43 The Legal Minefield: Why Talking About Health Is Terrifying for Building Professionals
00:51:23 Think Light Air: Translating Environmental Data into Human Health Impact Scores
01:40:37 Beyond Wells-Riley: Modeling Vulnerability, Not Just Exposure
01:28:54 The Path Forward: Regulation, Education, and the Courage to Do the Hard Thing

This week, we tackle a question that cuts through decades of technical progress and scientific consensus: What if the reason we still don't have clean indoor air isn't because we lack the technology—but because we lack the policy to actually implement it?

The paper is a policy commentary titled Federal and State Policy Opportunities to Improve Indoor Air Quality, published in the Journal of Health Security. It's authored by a powerhouse group of experts, including Georgia Lagoudas and colleagues from Brown University, Harvard, and several other leading institutions. Many of them have been previous guests on this podcast. This isn't a theoretical exercise. It's a roadmap—a practical, actionable menu of policy interventions that could finally bring indoor air quality into the same regulatory and public health framework that we've successfully built for drinking water, fire safety, and smoking bans.

Here's the glaring truth: we spend about 90% of our time indoors, yet we have no unified national initiative for clean indoor air. We have the Clean Air Act. We have the EPA regulating outdoor air. But outdoor regulations completely fail to account for the fact that outdoor pollutants make their way inside—where we spend all our time—and they ignore the fact that indoor spaces have their own unique pollutant sources. Concentrations of certain pollutants can be two to five times higher indoors than outdoors. And outdoor regulations do absolutely nothing to address one of the biggest indoor threats: the spread of respiratory pathogens like COVID-19 and influenza.

Key Topics Discussed:

The Current Mess: The federal government doesn't really regulate indoor air outside of occupational settings, leaving jurisdiction to state and local governments. Building codes are adopted and enforced locally, creating a massive patchwork of different standards. Some states like California, Connecticut, and Minnesota have taken steps, especially for schools, but there's no comprehensive national roadmap.

Develop Health-Based Indoor Air Quality Targets: Right now, building owners and facility managers don't have a simple unified goal. We need clear thresholds for easy-to-measure indicators like carbon dioxide and PM2.5. The EPA or a coalition of NGOs should publish voluntary health-based targets, providing a clear benchmark that states and local entities can adopt. If you don't know what the target is, you can't hit it.

Support States and Local Communities to Adopt Standards: Develop a national model indoor air quality code—similar to national model energy codes. Provide tax incentives to commercial buildings that make indoor air quality improvements, similar to deductions for energy efficient buildings. Create a state playbook filled with template language for regulations and building codes to make it easy for local governments to take action.

Implement Sector-Specific Standards: Schools need indoor air quality monitors, regular HVAC inspections, and better filtration. Nursing homes should have indoor air quality standards as a strict condition of participation, just like hospitals. Federal buildings housing around a million federal employees need robust ventilation verification programs. OSHA needs to update its permissible exposure limits—many were developed in the 1970s, nearly half a century ago.

The Two Biggest Priorities: Developing health-based indoor air quality targets and getting states to adopt indoor air quality building standards. If we can agree on what good air looks like and put it into the building code, the market will innovate to meet those demands.

Federal and State Policy Opportunities to Improve Indoor Air Quality

10.1177/23265094251410880 (https://doi.org/10.1177/23265094251410880)

The One Take Podcast in Partnership with

SafeTraces (https://www.safetraces.com/) and Inbiot (https://www.inbiot.es/?utm_campaign=simon&utm_source=airqualitymatters&utm_medium=podcast)

Do check them out in the links and on the Air Quality Matters Website (https://www.airqualitymatters.net/podcast)

Chapters

00:00:00 Introduction: The Missing Framework for Clean Indoor Air
00:01:12 The Glaring Gap: Why Indoor Air Quality Has Been Ignored
00:01:45 Why Outdoor Regulations Fail Indoors
00:02:22 The Astronomical Cost of Inaction
00:03:01 The Current Mess: A Patchwork of Standards
00:03:55 Recommendation One: Health-Based Indoor Air Quality Targets
00:04:43 Recommendation Two: Supporting States with Standards and Financing
00:05:38 Recommendation Three: Sector-Specific Standards
00:07:13 Recommendation Four: Research and the Wild West of Air Purifiers
00:08:30 The Bottom Line: Clean Air Is a Choice We Must Make