Air Quality Matters

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

This week, we sit down with Frank Kelly, Professor at Imperial College London and Director of the Environmental Research Group, to examine a question that fundamentally challenges how we think about air pollution: What if the real danger isn't just how much dust we're breathing, but what that dust is made of and what it does to our bodies at a cellular level?

For over three decades, Frank Kelly has been one of the architects of London's modern understanding of air quality. His pioneering work on the oxidative potential of particulate matter has transformed how we evaluate the toxicity of everything from diesel exhaust to wood smoke. By proving how these pollutants trigger harmful free radical reactions and deplete antioxidants in the lungs, he provided the scientific backbone for London's most ambitious public health interventions, including the Congestion Charging Zone and Ultra Low Emissions Zone.

Key Topics Discussed:

Beyond Size and Mass: Why PM10, PM2.5, and ultrafine particles are categorized by size, but size alone doesn't tell us what's actually harmful. The real story is in the chemistry, the physics, and the biology of what those particles carry and what they do when they reach the lung.

The Meteor Analogy: Particulate matter isn't just carbon spheres. It's a complex, ever-changing cocktail of metals, gases, chemicals, and biological material that picks up and sheds components as it moves through the environment and into our bodies.

Oxidative Potential: What free radicals are, why transition metals on particle surfaces drive oxidative stress, and how the body's antioxidant defences like glutathione, vitamin C, and vitamin E fight back. When the balance tips, inflammation and cellular damage begin.

The Seesaw Model: On one side, you have particulate pollution with oxidative potential. On the other, your body's natural defences. Your genetics, your diet, and your environment all determine where you sit on that seesaw and when the damage starts.

The London Success Story: How Frank's research directly influenced the introduction of the Ultra Low Emissions Zone. The data showed that children living in East London exposed to heavy traffic pollution had slower lung growth than children outside London. That evidence became the catalyst for policy change.

Indoor Air Quality and the Well Home Study: Over 100 homes in West London instrumented for two months each to understand indoor pollution sources. The findings: damp and mould in social housing, gas cooking as a major pollutant source, and pollution migrating from kitchens into children's bedrooms where it stayed trapped overnight.

The Microplastics Problem: Modern tyres are 55% plastic. As the fossil fuel industry loses its market in surface transport, it's shifting to plastic production. Frank's team has developed methods to characterize plastic particles in air, water, and food. The challenge: distinguishing plastic signatures from human tissue in toxicology studies.

The Future of Air Quality Monitoring: Moving beyond mass-based metrics to real-time oxidative potential monitoring. Frank's team is developing prototype instruments that measure free radical activity in the air instantaneously, allowing us to identify which pollution sources are truly harmful.

GUEST:

Frank Kelly

Professor, Imperial College London | Director, Environmental Research Group

https://www.imperial.ac.uk/people/frank.kelly

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 Hidden Complexity of Particulate Matter
00:05:50 Understanding PM10, PM2.5, and Ultrafine Particles
00:08:01 The Lung as an Open Door: Why We're Vulnerable
00:09:52 The Meteor Effect: What Particles Are Really Made Of
00:20:41 The Seesaw Battle: Oxidative Potential and Free Radicals
00:25:46 The London Laboratory: Evidence That Drove the Ultra Low Emission Zone
00:59:13 The Indoor Air Quality Challenge: A New Frontier
01:11:43 The Kitchen Problem: Why Cooking Dominates Indoor Pollution
01:26:46 The Research Ecosystem: Eight Teams Tackling Air Quality
01:44:51 The Future: Real-Time Oxidative Potential Monitoring

This week, we dive into a question that challenges one of the most common assumptions in building energy efficiency: What if the chemical tests we use to validate air cleaning technology are completely missing the point—and what if the human nose is actually the most reliable instrument we have?

The paper is titled A Method for Testing the Gas Phase Air Cleaners Using Sensory Assessment of Air Quality, published in the Journal of Building and Environment. It's authored by Cantor Amada, Lee Fang, Pavel Wargocki, and colleagues from Waseda University in Japan and the Technical University of Denmark. This research was conducted as part of the IEA Energy and Buildings and Communities Annex 78 project, and it proposes a radically practical testing protocol for gas phase air cleaners—one that puts human perception at the center, not just chemical spreadsheets.

But here's the problem. Current standards typically test these air cleaners by challenging them with a few selected chemicals—measuring how well they remove formaldehyde, for example. But indoor air contains hundreds of different gaseous pollutants. If you only use chemical analysis on a handful of compounds, you might completely underestimate real-world performance. Worse, you might completely miss harmful byproducts the air cleaner is actually creating.

Key Topics Discussed:

Subtractive vs. Additive Air Cleaners: Subtractive cleaners remove chemicals using things like activated carbon. Additive cleaners decompose chemicals using active components like photocatalytic oxidation, ion generators, UV, or ozone. Some additive technologies can transform relatively harmless pollutants into dangerous unwanted species—or pump ozone into the space. If your chemical test isn't looking for those specific byproducts, the machine gets a pass grade while actively making the room worse.

The Two-Phase Testing Protocol: Phase one is a screening phase—do no harm. The goal is simply to make sure the air cleaner doesn't have a negative effect on air quality. Phase two is the deep dive, testing the air cleaners at various ventilation rates from very low to standard levels, with panelists rating acceptability and odor intensity.

The UVO Zone Device Failed Immediately: One additive air cleaner—a UVO zone device—actually increased the odor intensity in the room, particularly when humans were present. It was dropped from the study. An ion generator was allowed through to phase two just to see if poor results would be repeated. They were. It significantly decreased the acceptability of the air.

Activated Carbon Worked—But Only for Building Materials: When the pollution source was purely building materials like old carpets and linoleum, the activated carbon air cleaners significantly improved air quality. But when the pollutant source was humans—people just sitting there breathing and existing—the air cleaners did not significantly improve perceived air quality.

The Chemical Data Lied: Parallel chemical measurements showed that total VOCs dropped significantly when using the carbon air cleaners, regardless of whether the pollutant came from materials or humans. If you were only looking at the chemical spreadsheet, you would say the air cleaners worked perfectly in all scenarios. But the human panelists were telling a completely different story. The chemical measurements simply did not match the sensory evaluations.

The ISO 16000-44 Standard: This research heavily supports the new ISO 16000-44 standard approved in 2023, which outlines the test method for measuring perceived indoor air quality to test the performance of gas phase cleaners. The sector is slowly recognizing that the human experience is a metric.

A Method for Testing the Gas Phase Air Cleaners Using Sensory Assessment of Air Quality

https://doi.org/10.1016/j.buildenv.2024.111630

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 Challenge of Testing Gas Phase Air Cleaners
00:01:14 The Energy Dilemma: Why Air Cleaners Matter for Buildings
00:02:12 The Chemical Testing Problem: What Current Standards Miss
00:02:53 Additive vs Subtractive: Understanding Air Cleaner Technologies
00:03:43 The Human Nose Solution: Sensory Assessment as a Testing Method
00:04:04 The Experimental Setup: Real Materials and Real People
00:04:50 Phase One Results: The Do No Harm Screening
00:05:54 Phase Two Deep Dive: Testing at Various Ventilation Rates
00:06:31 The Big Reveal: When Chemical Data Doesn't Match Human Experience
00:07:28 The Massive Implication: Why Chemical Analysis Alone Fails
00:08:21 The Path Forward: ISO 16000-44 and Sensory Testing Standards
00:09:24 Closing Thoughts: The Human Nose Remains Essential

This week, we sit down with Mark Lynn, Managing Director of Eden Renewable Innovations and Chair of the Alliance for Sustainable Building Products, to explore a question that cuts to the heart of indoor air quality: What if the materials we bring into our buildings are the forgotten foundation of healthy indoor air—and what if natural materials offer solutions we've systematically overlooked for decades?

Recorded live at the Alliance for Sustainable Building Products Annual Healthy Buildings Conference in London, this conversation takes us deep into the world of building materials, their chemistry, their moisture behavior, and their profound impact on the air we breathe indoors. Mark brings over two decades of experience in natural fiber insulation and nearly 30 years in natural building materials, with a particular focus on building physics and the chemistry of materials.

Key Topics Discussed:

The Forgotten Inflection Point: In the mid to late 1990s, society cared deeply about indoor air quality. MDF was scrutinized for formaldehyde emissions. Smoking bans were introduced. Ventilation moved up the agenda. But somewhere around the early 2000s, we shifted our focus entirely to ventilation as the sole solution—and stopped asking hard questions about the materials themselves.

The Chemical Experiment: A single 1970s living room contained perhaps a dozen materials, most locally sourced. Today's living rooms contain thousands of materials, sourced globally, with complex chemistries we barely understand. We are living in a grand chemical experiment, and the results won't be clear for decades.

Hurdle Technology and the Swiss Cheese Model: Ventilation alone is not enough. Good indoor air quality requires multiple layers of defense—elimination of harmful materials at source, moisture buffering through hygroscopic materials like wood and wool, and only then, ventilation as a final backstop. Relying on ventilation alone assumes it works perfectly. It rarely does.

The Moisture Problem: Ventilation removes 95% of moisture from a building. But the remaining 5% can cause catastrophic problems—mold, structural decay, and poor air quality. Natural materials like sheep's wool and wood fiber can buffer moisture safely, acting as a critical redundancy when ventilation underperforms.

Wool and Formaldehyde: Sheep's wool uniquely reacts with formaldehyde through a condensation reaction, permanently binding the carbon from formaldehyde into the keratin protein structure of the fiber. It's not just inert—it's actively neutralizing a harmful indoor pollutant.

GUEST:

Mark Lynn

Managing Director, Eden Renewable Innovations | Chair, Alliance for Sustainable Building Products

https://asbp.org.uk/

https://thermafleece.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 Forgotten Fundamentals of Building Materials
00:02:19 The Inflection Points: When We Cared About Indoor Air Quality
00:05:16 The Chemical Soup: Living Rooms Then and Now
00:08:16 The Grand Chemical Experiment: Unknown Long-Term Impacts
00:10:58 Custodianship and Consumption: The Lost Art of Make Do and Mend
00:13:07 Particles as Trojan Horses: The Chemistry Happening in Your Home
00:15:22 Hurdle Technology: The Swiss Cheese Approach to Risk Management
00:17:34 Learning from Food: Why Digestive Biscuits Have Better Moisture Science
00:20:15 The Ventilation Fallacy: What Happens When Your Backup Plan Fails
00:25:00 Natural Technology: The Evolution Already Solved the Problem
00:32:59 The Standards Dilemma: Innovation Versus Established Frameworks
00:36:00 Post-Completion Reality: When Sensors Reveal the Truth
00:38:27 Transparency and AI: The Coming Revolution in Material Selection
00:57:59 Sheep's Wool and Formaldehyde: When Materials Fight Pollutants
01:01:20 The Trajectory Forward: Capacity, Policy, and Bottom-Up Change
01:04:39 From Belfast to Buildings: Optimism Through Experience

This week, we step outside the usual world of homes, schools, and offices to ask a question that might reshape how we think about the hospitality industry: What if the physical performance of a hotel room matters just as much as the quality of service—and what if guests are already telling us this in their online reviews?

The paper is titled The Impact of Indoor Environmental Quality on Tourist Accommodation Ratings Using Guest Reviews, published in the Journal of Building and Environment. It's authored by Fan Zhang and colleagues from Griffith University, the University of New South Wales, and several other international institutions. Using web mining and artificial intelligence, they analyzed over half a million Booking.com reviews from Australian hotels and serviced apartments to understand how indoor environmental quality—air quality, acoustics, thermal comfort, lighting—actually drives guest satisfaction and ratings.

Traditionally, measuring occupant satisfaction in hotels has been nearly impossible. Post-occupancy evaluations require structured surveys, but try getting a business traveler rushing to the airport at 6am to fill in a 20-page questionnaire about ventilation rates. It's just not going to happen. So instead, these researchers used natural language processing to extract the actual, unprompted words from guests who stayed in these places—to see exactly what they care about.

Key Topics Discussed:

Three Factor Theory: A framework that categorizes any product or service feature into three buckets: basic factors (dissatisfiers), performance factors (the better it is, the happier you are), and excitement factors (unexpected bonuses). Almost all indoor environmental quality factors function as basic factors—guests expect them to be good, and if they're not, ratings plummet.

The Big Three Failures: Poor cleanliness, poor indoor air quality, and bad acoustics were the specific failures that dragged accommodation ratings down the most. Stuffy rooms, musty smells, and hearing the elevator rattling through the walls all night are directly torching hotel revenues by driving down public ratings.

Indoor Environmental Quality Accounts for 33% of Guest Ratings: In budget hotels, nearly a third of a customer's overall rating is driven by indoor environmental quality. In luxury accommodation, it's still about 24%. You can have the best marketing team and the friendliest staff, but if your building is fundamentally underventilated, your business will suffer.

The COVID Effect: The pandemic drastically amplified our sensitivity to poor indoor environments. During COVID, the negative impact of poor indoor air quality and cleanliness on guest ratings got significantly stronger. People suddenly equated visible cleanliness and fresh air with their own personal safety and survival.

The View Exception: In budget accommodation, a nice view was an excitement factor—people didn't expect it, so when they got one, they were thrilled. But in luxury hotels, the view reverted to being a basic factor. If you're paying 5-star prices, you expect 5-star views.

The Case for IEQ Benchmarking: The researchers suggest that policymakers and industry leaders should implement formal indoor environmental quality benchmarking for hotels—similar to Australia's NABERS rating for office buildings. Imagine being able to check a hotel's certified ventilation and air quality rating before you even book a room.

The Impact of Indoor Environmental Quality on Tourist Accommodation Ratings Using Guest Reviews

https://doi.org/10.1016/j.buildenv.2025.113135

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 Overlooked Environment of Hotels
00:01:21 The Hospitality Blind Spot: Service vs Environment
00:01:52 The POE Problem: Why Traditional Surveys Fail in Hotels
00:02:24 The AI Solution: Mining Half a Million Guest Reviews
00:02:56 Three Factor Theory: The Framework for Understanding Buildings
00:04:06 The Eye-Opening Results: IEQ as a Basic Factor
00:05:03 The Triple Threat: Cleanliness, Air Quality, and Acoustics
00:05:44 The View Exception: Budget Thrills vs Luxury Expectations
00:06:30 The COVID Effect: When Air Quality Became Survival
00:07:53 The Bottom Line: IEQ Accounts for 33 Percent of Hotel Ratings
00:08:37 The Future: IEQ Benchmarking and Certification for Hotels
00:09:18 Study Limitations and the Reality of Guest Perception
00:09:55 The Main Takeaway: Engineering as Front-Line Business Survival