Chris Iddon
@chrisiddon.bsky.social
Music, walking, ventilation.
Research fellow
Chair of the CIBSE natural ventilation group
Research fellow
Chair of the CIBSE natural ventilation group
Reposted by Chris Iddon
The stuff you find when you actually read the RCTs in a systematic review...
This paper is one of the foundational studies on vitamin D to prevent respiratory infections in kids. Cited 1,400 times as per Google Scholar.
This paper is one of the foundational studies on vitamin D to prevent respiratory infections in kids. Cited 1,400 times as per Google Scholar.
November 26, 2025 at 9:15 PM
The stuff you find when you actually read the RCTs in a systematic review...
This paper is one of the foundational studies on vitamin D to prevent respiratory infections in kids. Cited 1,400 times as per Google Scholar.
This paper is one of the foundational studies on vitamin D to prevent respiratory infections in kids. Cited 1,400 times as per Google Scholar.
New study on HEPA air cleaners in Finnish school study.
Kids fill in daily diary of respiratory symptoms and the prevalence of symptoms reduced when the air cleaner was on.
However the prevalence also decreased when the air cleaner was on but HEPA removed 🧵
Kids fill in daily diary of respiratory symptoms and the prevalence of symptoms reduced when the air cleaner was on.
However the prevalence also decreased when the air cleaner was on but HEPA removed 🧵
November 21, 2025 at 5:49 PM
New study on HEPA air cleaners in Finnish school study.
Kids fill in daily diary of respiratory symptoms and the prevalence of symptoms reduced when the air cleaner was on.
However the prevalence also decreased when the air cleaner was on but HEPA removed 🧵
Kids fill in daily diary of respiratory symptoms and the prevalence of symptoms reduced when the air cleaner was on.
However the prevalence also decreased when the air cleaner was on but HEPA removed 🧵
During the COVID-19 pandemic in 2021, researchers monitored air quality in marquees and semi-outdoor venues at UK mass gatherings to understand ventilation and airborne infection risk — work that directly informed how such events could safely reopen. 🧵
November 6, 2025 at 1:44 PM
During the COVID-19 pandemic in 2021, researchers monitored air quality in marquees and semi-outdoor venues at UK mass gatherings to understand ventilation and airborne infection risk — work that directly informed how such events could safely reopen. 🧵
Reposted by Chris Iddon
A lot of the analysis on this misses the mark:
• “They weren’t on” — maybe, but filtration data says otherwise
• “Too small / not ASHRAE 241” — data disagrees.
And none of it actually says anything about transmission of respiratory illnesses.
🧵1/n
• “They weren’t on” — maybe, but filtration data says otherwise
• “Too small / not ASHRAE 241” — data disagrees.
And none of it actually says anything about transmission of respiratory illnesses.
🧵1/n
HEPA purifiers not tied to less #viral exposure in elementary classrooms, analysis finds
#HEPA purifiers were associated with a 33% decrease in viral diversity, but the reduction wasn't linked to fewer school absences.
www.cidrap.umn.edu/i...
#HEPA purifiers were associated with a 33% decrease in viral diversity, but the reduction wasn't linked to fewer school absences.
www.cidrap.umn.edu/i...
October 15, 2025 at 7:33 PM
A lot of the analysis on this misses the mark:
• “They weren’t on” — maybe, but filtration data says otherwise
• “Too small / not ASHRAE 241” — data disagrees.
And none of it actually says anything about transmission of respiratory illnesses.
🧵1/n
• “They weren’t on” — maybe, but filtration data says otherwise
• “Too small / not ASHRAE 241” — data disagrees.
And none of it actually says anything about transmission of respiratory illnesses.
🧵1/n
A lot of the analysis on this misses the mark:
• “They weren’t on” — maybe, but filtration data says otherwise
• “Too small / not ASHRAE 241” — data disagrees.
And none of it actually says anything about transmission of respiratory illnesses.
🧵1/n
• “They weren’t on” — maybe, but filtration data says otherwise
• “Too small / not ASHRAE 241” — data disagrees.
And none of it actually says anything about transmission of respiratory illnesses.
🧵1/n
HEPA purifiers not tied to less #viral exposure in elementary classrooms, analysis finds
#HEPA purifiers were associated with a 33% decrease in viral diversity, but the reduction wasn't linked to fewer school absences.
www.cidrap.umn.edu/i...
#HEPA purifiers were associated with a 33% decrease in viral diversity, but the reduction wasn't linked to fewer school absences.
www.cidrap.umn.edu/i...
October 15, 2025 at 7:33 PM
A lot of the analysis on this misses the mark:
• “They weren’t on” — maybe, but filtration data says otherwise
• “Too small / not ASHRAE 241” — data disagrees.
And none of it actually says anything about transmission of respiratory illnesses.
🧵1/n
• “They weren’t on” — maybe, but filtration data says otherwise
• “Too small / not ASHRAE 241” — data disagrees.
And none of it actually says anything about transmission of respiratory illnesses.
🧵1/n
Reposted by Chris Iddon
With UK heatwaves intensifying, are passive cooling strategies enough? At CIBSE’s seminar, experts explored natural ventilation limits, AirCon efficiency, façade carbon trade-offs & why overheating in schools is a learning crisis. cibsejournal.com/technical/pu...
Pushing the cooling limit: CIBSE Natural Ventilation Group - CIBSE Journal
The limits of passive cooling, healthy learning environments and mitigating overheating were the core subjects of a topical summer event hosted by the CIBSE Natural Ventilation Group in July. Chair Ch...
cibsejournal.com
September 1, 2025 at 11:07 AM
With UK heatwaves intensifying, are passive cooling strategies enough? At CIBSE’s seminar, experts explored natural ventilation limits, AirCon efficiency, façade carbon trade-offs & why overheating in schools is a learning crisis. cibsejournal.com/technical/pu...
With UK heatwaves intensifying, are passive cooling strategies enough? At CIBSE’s seminar, experts explored natural ventilation limits, AirCon efficiency, façade carbon trade-offs & why overheating in schools is a learning crisis. cibsejournal.com/technical/pu...
Pushing the cooling limit: CIBSE Natural Ventilation Group - CIBSE Journal
The limits of passive cooling, healthy learning environments and mitigating overheating were the core subjects of a topical summer event hosted by the CIBSE Natural Ventilation Group in July. Chair Ch...
cibsejournal.com
September 1, 2025 at 11:07 AM
With UK heatwaves intensifying, are passive cooling strategies enough? At CIBSE’s seminar, experts explored natural ventilation limits, AirCon efficiency, façade carbon trade-offs & why overheating in schools is a learning crisis. cibsejournal.com/technical/pu...
ASHRAE Standard 241 sets guidelines for how much “clean air” (via ventilation, filtration, etc.) is needed in buildings to reduce the airborne spread of infectious diseases like COVID-19. But how were these numbers chosen? 1/n
July 14, 2025 at 11:10 AM
ASHRAE Standard 241 sets guidelines for how much “clean air” (via ventilation, filtration, etc.) is needed in buildings to reduce the airborne spread of infectious diseases like COVID-19. But how were these numbers chosen? 1/n
Reposted by Chris Iddon
New oped from @benjonesieq.bsky.social
& me
💨 The push for better school ventilation is well-meaning, but claims that it boosts cognition or learning lack strong, causal evidence. Many studies are low quality, poorly controlled, and often overstate effects. #IAQ #ventilation #education 1/5
& me
💨 The push for better school ventilation is well-meaning, but claims that it boosts cognition or learning lack strong, causal evidence. Many studies are low quality, poorly controlled, and often overstate effects. #IAQ #ventilation #education 1/5
June 25, 2025 at 11:14 AM
New oped from @benjonesieq.bsky.social
& me
💨 The push for better school ventilation is well-meaning, but claims that it boosts cognition or learning lack strong, causal evidence. Many studies are low quality, poorly controlled, and often overstate effects. #IAQ #ventilation #education 1/5
& me
💨 The push for better school ventilation is well-meaning, but claims that it boosts cognition or learning lack strong, causal evidence. Many studies are low quality, poorly controlled, and often overstate effects. #IAQ #ventilation #education 1/5
Reposted by Chris Iddon
The June issue of the #REHVA #Journal is out now! 📯
"#Education #Buildings: a Net Zero Transition Conducive to #Health and #Cognitive Performance".
📱 Read it online: www.rehva.eu/rehva-journa...
📨 Want to receive the #REHVA Journal in your inbox? Subscribe here: www.rehva.eu/newsletter-s...
"#Education #Buildings: a Net Zero Transition Conducive to #Health and #Cognitive Performance".
📱 Read it online: www.rehva.eu/rehva-journa...
📨 Want to receive the #REHVA Journal in your inbox? Subscribe here: www.rehva.eu/newsletter-s...
June 24, 2025 at 1:57 PM
The June issue of the #REHVA #Journal is out now! 📯
"#Education #Buildings: a Net Zero Transition Conducive to #Health and #Cognitive Performance".
📱 Read it online: www.rehva.eu/rehva-journa...
📨 Want to receive the #REHVA Journal in your inbox? Subscribe here: www.rehva.eu/newsletter-s...
"#Education #Buildings: a Net Zero Transition Conducive to #Health and #Cognitive Performance".
📱 Read it online: www.rehva.eu/rehva-journa...
📨 Want to receive the #REHVA Journal in your inbox? Subscribe here: www.rehva.eu/newsletter-s...
New oped from @benjonesieq.bsky.social
& me
💨 The push for better school ventilation is well-meaning, but claims that it boosts cognition or learning lack strong, causal evidence. Many studies are low quality, poorly controlled, and often overstate effects. #IAQ #ventilation #education 1/5
& me
💨 The push for better school ventilation is well-meaning, but claims that it boosts cognition or learning lack strong, causal evidence. Many studies are low quality, poorly controlled, and often overstate effects. #IAQ #ventilation #education 1/5
June 25, 2025 at 11:14 AM
New oped from @benjonesieq.bsky.social
& me
💨 The push for better school ventilation is well-meaning, but claims that it boosts cognition or learning lack strong, causal evidence. Many studies are low quality, poorly controlled, and often overstate effects. #IAQ #ventilation #education 1/5
& me
💨 The push for better school ventilation is well-meaning, but claims that it boosts cognition or learning lack strong, causal evidence. Many studies are low quality, poorly controlled, and often overstate effects. #IAQ #ventilation #education 1/5
Just read one of the most ridiculous claims in a scientific journal discussion I've ever seen 👀
a therapeutic approach to gut microbiome to improve lung health impacts from air pollution 🤯
in rural Uganda!
read on if you want to see how..1/n
a therapeutic approach to gut microbiome to improve lung health impacts from air pollution 🤯
in rural Uganda!
read on if you want to see how..1/n
June 6, 2025 at 1:19 PM
Just read one of the most ridiculous claims in a scientific journal discussion I've ever seen 👀
a therapeutic approach to gut microbiome to improve lung health impacts from air pollution 🤯
in rural Uganda!
read on if you want to see how..1/n
a therapeutic approach to gut microbiome to improve lung health impacts from air pollution 🤯
in rural Uganda!
read on if you want to see how..1/n
New paper describes an in vitro method to infect cell culture with different flu strains by direct inoculation and by aerolised viral solution. Whilst it is an interesting novel methodology, I think it is limited in what it can tell us about the nature of aerosol transmission 1/n
June 5, 2025 at 1:28 PM
New paper describes an in vitro method to infect cell culture with different flu strains by direct inoculation and by aerolised viral solution. Whilst it is an interesting novel methodology, I think it is limited in what it can tell us about the nature of aerosol transmission 1/n
The pandemic was a time when you would have thought people might want to improve their ventilation. But, behaviour change is hard because there are many barriers to change.
Great new study by on behavioural aspects of ventilation in hospitality venues. Many monitored venues had poor ventilation, but hosts list many barriers to improve - tho some venues attempt to improve following info campaign.
let's see why it's not always simple to ⬆️ ventilation:
let's see why it's not always simple to ⬆️ ventilation:
May 18, 2025 at 7:04 PM
The pandemic was a time when you would have thought people might want to improve their ventilation. But, behaviour change is hard because there are many barriers to change.
Reposted by Chris Iddon
Great new study by on behavioural aspects of ventilation in hospitality venues. Many monitored venues had poor ventilation, but hosts list many barriers to improve - tho some venues attempt to improve following info campaign.
let's see why it's not always simple to ⬆️ ventilation:
let's see why it's not always simple to ⬆️ ventilation:
May 16, 2025 at 10:35 AM
Great new study by on behavioural aspects of ventilation in hospitality venues. Many monitored venues had poor ventilation, but hosts list many barriers to improve - tho some venues attempt to improve following info campaign.
let's see why it's not always simple to ⬆️ ventilation:
let's see why it's not always simple to ⬆️ ventilation:
Great new study by on behavioural aspects of ventilation in hospitality venues. Many monitored venues had poor ventilation, but hosts list many barriers to improve - tho some venues attempt to improve following info campaign.
let's see why it's not always simple to ⬆️ ventilation:
let's see why it's not always simple to ⬆️ ventilation:
May 16, 2025 at 10:35 AM
Great new study by on behavioural aspects of ventilation in hospitality venues. Many monitored venues had poor ventilation, but hosts list many barriers to improve - tho some venues attempt to improve following info campaign.
let's see why it's not always simple to ⬆️ ventilation:
let's see why it's not always simple to ⬆️ ventilation:
Reposted by Chris Iddon
or a new study shows that either, or a combination of:
▪️reduced viral emission (bcos air cleaner added several days later from initial readings)
▪️changes to window ventilation
▪️presence of an air cleaner
see below for fag packet calc to show it can't all be due to air cleaner...
▪️reduced viral emission (bcos air cleaner added several days later from initial readings)
▪️changes to window ventilation
▪️presence of an air cleaner
see below for fag packet calc to show it can't all be due to air cleaner...
A new study shows that air cleaners can reduce up to 98,1 % of viral load in the air of a #COVID patient's room with confirmed positive airborne viral RNA.
Rooms with HEPA ventilation had zero virus detected.
👏 #CleantheAir in hospitals and schools!👏
www.sciencedirect.com/science/arti...
Rooms with HEPA ventilation had zero virus detected.
👏 #CleantheAir in hospitals and schools!👏
www.sciencedirect.com/science/arti...
May 13, 2025 at 7:04 PM
or a new study shows that either, or a combination of:
▪️reduced viral emission (bcos air cleaner added several days later from initial readings)
▪️changes to window ventilation
▪️presence of an air cleaner
see below for fag packet calc to show it can't all be due to air cleaner...
▪️reduced viral emission (bcos air cleaner added several days later from initial readings)
▪️changes to window ventilation
▪️presence of an air cleaner
see below for fag packet calc to show it can't all be due to air cleaner...
or a new study shows that either, or a combination of:
▪️reduced viral emission (bcos air cleaner added several days later from initial readings)
▪️changes to window ventilation
▪️presence of an air cleaner
see below for fag packet calc to show it can't all be due to air cleaner...
▪️reduced viral emission (bcos air cleaner added several days later from initial readings)
▪️changes to window ventilation
▪️presence of an air cleaner
see below for fag packet calc to show it can't all be due to air cleaner...
A new study shows that air cleaners can reduce up to 98,1 % of viral load in the air of a #COVID patient's room with confirmed positive airborne viral RNA.
Rooms with HEPA ventilation had zero virus detected.
👏 #CleantheAir in hospitals and schools!👏
www.sciencedirect.com/science/arti...
Rooms with HEPA ventilation had zero virus detected.
👏 #CleantheAir in hospitals and schools!👏
www.sciencedirect.com/science/arti...
May 13, 2025 at 7:04 PM
or a new study shows that either, or a combination of:
▪️reduced viral emission (bcos air cleaner added several days later from initial readings)
▪️changes to window ventilation
▪️presence of an air cleaner
see below for fag packet calc to show it can't all be due to air cleaner...
▪️reduced viral emission (bcos air cleaner added several days later from initial readings)
▪️changes to window ventilation
▪️presence of an air cleaner
see below for fag packet calc to show it can't all be due to air cleaner...
Off to see Bjork's cornucopia experience today. Trips to see her at the cinema are always an experience. Be that the harrowing Dancer in the Dark or the strangely hypnotic Matthew Barney art film Drawing Restraint 9. I'm sure there will be something to remember
a woman in a green fur coat is standing in front of a blue background
ALT: a woman in a green fur coat is standing in front of a blue background
media.tenor.com
May 7, 2025 at 5:07 PM
Off to see Bjork's cornucopia experience today. Trips to see her at the cinema are always an experience. Be that the harrowing Dancer in the Dark or the strangely hypnotic Matthew Barney art film Drawing Restraint 9. I'm sure there will be something to remember
This really interesting paper on SARS-CoV-2 viral emission dynamics in a hamster model has just been published. There’s lots to unpack, but thought I’d start on this expt that investigates characteristics of close range emission 1/n
May 2, 2025 at 2:50 PM
This really interesting paper on SARS-CoV-2 viral emission dynamics in a hamster model has just been published. There’s lots to unpack, but thought I’d start on this expt that investigates characteristics of close range emission 1/n
Had a great time watching Stranger Things: The First Shadow. Fantastic special effects and illusions brought a gripping story to life.
May 2, 2025 at 6:40 AM
Had a great time watching Stranger Things: The First Shadow. Fantastic special effects and illusions brought a gripping story to life.
Nice headline, scant on details. it's just a report based on a presentation given by a researcher. Look forward to seeing the methods and data. Researchers report that unknown if reduced exposure to pollution or pathogens or both is causative factor in reported absence reduction
Putting air filters in classrooms seems to reduce student sick days by more than 10 per cent.
Air filters in classrooms reduce sick days by more than 10 per cent
Putting air filters in classrooms seems to boost student attendance, which may be due to them reducing levels of air pollution, pollen, pathogens or all three
www.newscientist.com
April 30, 2025 at 8:33 PM
Nice headline, scant on details. it's just a report based on a presentation given by a researcher. Look forward to seeing the methods and data. Researchers report that unknown if reduced exposure to pollution or pathogens or both is causative factor in reported absence reduction
Anyone know why the DHHS in the US have pulled the funding for this clinical trials for far UV to reduce indoor transmission of respiratory infections?
nationalacademies.org/our-work/cli...
nationalacademies.org/our-work/cli...
April 29, 2025 at 7:16 AM
Anyone know why the DHHS in the US have pulled the funding for this clinical trials for far UV to reduce indoor transmission of respiratory infections?
nationalacademies.org/our-work/cli...
nationalacademies.org/our-work/cli...
Disappointing that this headline suggests there may be causal links, when the article itself highlights the data is low quality wrt drawing any conclusions about UPF consumption and mortality
bbc.co.uk/news/article...
bbc.co.uk/news/article...
April 28, 2025 at 7:27 PM
Disappointing that this headline suggests there may be causal links, when the article itself highlights the data is low quality wrt drawing any conclusions about UPF consumption and mortality
bbc.co.uk/news/article...
bbc.co.uk/news/article...
Really interesting data showing how actual energy use is much lower than predicted energy use from residential EPC modelling. The gap may not be all down to how the housing is used by occupants but other assumptions that the model makes #cibsetechnicalsymposium
April 24, 2025 at 1:15 PM
Really interesting data showing how actual energy use is much lower than predicted energy use from residential EPC modelling. The gap may not be all down to how the housing is used by occupants but other assumptions that the model makes #cibsetechnicalsymposium