EPISODE · May 14, 2026 · 9 MIN
The Wrong Corner: How Air Purifier Placement Can Increase Infection Risk OT43
from Air Quality Matters · host Simon Jones
This week, we dive into a groundbreaking computational fluid dynamics study from KTH Royal Institute of Technology in Sweden that fundamentally challenges how we think about portable air cleaners in care homes: What if the single most important decision about air cleaning isn't which device you buy—but where you put it in the room? During the height of the COVID-19 pandemic, care homes experienced devastating mortality rates among elderly residents. These environments are uniquely challenging—combining elements of healthcare facilities with residential living spaces, housing vulnerable populations who spend prolonged periods indoors with limited mobility and compromised immune systems. Portable air cleaners emerged as a promising, accessible solution. But does it actually matter where you place them? Can you just plug them in wherever the cable reaches and assume the job is done? And critically, will the airflow create cold drafts that make elderly residents so uncomfortable they simply switch the device off? Key Topics Discussed: The Care Home Challenge: Why care homes represent such a unique built environment challenge. Vulnerable populations with reduced mobility, chronic illnesses, compromised thermoregulation making them sensitive to drafts, and prolonged indoor exposure without control over their immediate environment. Any intervention has to work within these constraints. The 74% Variation Problem: Using computational fluid dynamics simulations, researchers tested the same portable air cleaner in nine different locations within a typical care home room. The result: placement alone created a 74% variation in infection risk. Same machine, same room, same people—completely different outcomes based purely on where the device sat. The Worst Case Scenario: In one placement configuration, positioning the air cleaner near the infected healthcare worker created a powerful airflow jet that actively transported exhaled virus particles directly into the breathing zone of the elderly patient. The infection risk skyrocketed to 85.9%. The air cleaner didn't just fail—it made things dramatically worse. The Best Case Scenario: Placing the air cleaner in the centre of the room created the lowest infection risk—75 to 86% reduction compared to no air cleaner—by forming an invisible air barrier between occupants. But it's completely impractical due to tripping hazards in environments with wheelchairs, walking frames, and elderly residents with limited mobility. The Thermal Comfort Win: Across all tested scenarios, draft rates remained below the 10% discomfort threshold. This is critical. There's no point achieving perfect air quality if the occupant is freezing cold and turns the device off. The study proves portable air cleaners can reduce infection risk without compromising thermal comfort—if used correctly. The Training Gap: The on demand, plug and play nature of portable air cleaners means frontline workers—nurses, cleaners, facility managers—play a critical role in their effectiveness. Without proper training and clear visual guidance showing safe placement zones, we risk unintended consequences. Procurement isn't enough. Education is essential. CFD study on performance of portable air cleaner on infection risk and draught rate in care homes https://doi.org/10.1016/j.indenv.2026.100151 The Air Quality Matters Podcast in Partnership with Particles Plus https://particlesplus.com/ Eurovent (https://www.eurovent.eu/) - Aico (https://www.aico.co.uk/) - Lindab (https://www.lindab.ie/) 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) - Farmwood (https://farmwood.co.uk/) 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 One Take Format and This Week's CFD Study 00:01:03 The Care Home Crisis: Why COVID-19 Hit the Elderly So Hard 00:01:37 The Vulnerable Population: Mobility, Immunity, and Thermal Sensitivity 00:02:09 The Portable Air Cleaner Promise: Easy Solution or Placement Problem? 00:02:50 The CFD Simulation: Mapping Invisible Airflow and Virus Particles 00:03:43 The Good News: 75-86% Risk Reduction Without Creating Drafts 00:04:26 The Shocking Discovery: 74% Variation Based on Placement Alone 00:04:58 The Worst Case Scenario: When Air Cleaners Blow Virus Directly at Patients 00:05:45 The Best Placement Dilemma: Center of Room vs Practical Safety 00:06:47 The Real World Lesson: Education, Training, and Strategic Deployment
What this episode covers
This week, we dive into a groundbreaking computational fluid dynamics study from KTH Royal Institute of Technology in Sweden that fundamentally challenges how we think about portable air cleaners in care homes: What if the single most important decision about air cleaning isn't which device you buy—but where you put it in the room? During the height of the COVID-19 pandemic, care homes experienced devastating mortality rates among elderly residents. These environments are uniquely challenging—combining elements of healthcare facilities with residential living spaces, housing vulnerable populations who spend prolonged periods indoors with limited mobility and compromised immune systems. Portable air cleaners emerged as a promising, accessible solution. But does it actually matter where you place them? Can you just plug them in wherever the cable reaches and assume the job is done? And critically, will the airflow create cold drafts that make elderly residents so uncomfortable they simply switch the device off? Key Topics Discussed: The Care Home Challenge: Why care homes represent such a unique built environment challenge. Vulnerable populations with reduced mobility, chronic illnesses, compromised thermoregulation making them sensitive to drafts, and prolonged indoor exposure without control over their immediate environment. Any intervention has to work within these constraints. The 74% Variation Problem: Using computational fluid dynamics simulations, researchers tested the same portable air cleaner in nine different locations within a typical care home room. The result: placement alone created a 74% variation in infection risk. Same machine, same room, same people—completely different outcomes based purely on where the device sat. The Worst Case Scenario: In one placement configuration, positioning the air cleaner near the infected healthcare worker created a powerful airflow jet that actively transported exhaled virus particles directly into the breathing zone of the elderly patient. The infection risk skyrocketed to 85.9%. The air cleaner didn't just fail—it made things dramatically worse. The Best Case Scenario: Placing the air cleaner in the centre of the room created the lowest infection risk—75 to 86% reduction compared to no air cleaner—by forming an invisible air barrier between occupants. But it's completely impractical due to tripping hazards in environments with wheelchairs, walking frames, and elderly residents with limited mobility. The Thermal Comfort Win: Across all tested scenarios, draft rates remained below the 10% discomfort threshold. This is critical. There's no point achieving perfect air quality if the occupant is freezing cold and turns the device off. The study proves portable air cleaners can reduce infection risk without compromising thermal comfort—if used correctly. The Training Gap: The on demand, plug and play nature of portable air cleaners means frontline workers—nurses, cleaners, facility managers—play a critical role in their effectiveness. Without proper training and clear visual guidance showing safe placement zones, we risk unintended consequences. Procurement isn't enough. Education is essential. CFD study on performance of portable air cleaner on infection risk and draught rate in care homes https://doi.org/10.1016/j.indenv.2026.100151 The Air Quality Matters Podcast in Partnership with Particles Plus https://particlesplus.com/ Eurovent (https://www.eurovent.eu/) - Aico (https://www.aico.co.uk/) - Lindab (https://www.lindab.ie/) 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) - Farmwood (https://farmwood.co.uk/) 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 One Take Format and This Week's CFD Study 00:01:03 The Care Home Crisis: Why COVID-19 Hit the Elderly So Hard 00:01:37 The Vulnerable Population: Mobility, Immunity, and Thermal Sensitivity 00:02:09 The Portable Air Cleaner Promise: Easy Solution or Placement Problem? 00:02:50 The CFD Simulation: Mapping Invisible Airflow and Virus Particles 00:03:43 The Good News: 75-86% Risk Reduction Without Creating Drafts 00:04:26 The Shocking Discovery: 74% Variation Based on Placement Alone 00:04:58 The Worst Case Scenario: When Air Cleaners Blow Virus Directly at Patients 00:05:45 The Best Placement Dilemma: Center of Room vs Practical Safety 00:06:47 The Real World Lesson: Education, Training, and Strategic Deployment
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The Wrong Corner: How Air Purifier Placement Can Increase Infection Risk OT43
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