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CO2 sensor in a public place. An airplane, a library, a restaurant, a supermarket, a medical waiting room or other. `
No possibility of placing it 1 m from you or another person.
Where would you place it if you have the choice between your yoga pants, on a wristband, or in an open handbag, if you want to have the most accurate CO2 data?
Which of these 3 possibilities in your opinion overestimates or underestimates the CO2, according to you?
I have finished tests with CO2 sensors, 8 models that are compared to Aranet 4 used as a reference value. Humble open science, nothing very elaborate.
I would like to read your thought before I share the results
I don't want to say any more so as not to influence your answers
I am going to state what I would have answered before testing. And later we'll see if my tests make me change my mind. I hadn't thought about the question very much, but I instinctively thought that a bracelet would have been the best choice, an open handbag the 2nd choice, and pants pockets the 3rd choice. I figured that pants pockets would underestimate CO2 way too much. That the open bag would also underestimate CO2, but not as badly as pants pockets. And that the bracelet would overestimate CO2, but the gap with the measurement taken at 1 meter would be more favorable than the other two options. That's why I bought the Airspot Health, based on this idea I had formed
"C'est la vie, quand l'été, tourne à l'automne"
I made this music and autumn color photo video montage back in 2018 while staying at a motel, as my love was at the hospital by her father's bedside. It uses photos taken during cabin getaways, around my place, on walks to visit my mother, or on my way to the clinic where I worked near my house (I used to walk through a park to get there) vimeo.com/295945933
j'adore les couleurs d'automne. Toute cette beauté éphémère que je ne veux surtout pas rater. ça me fait un effet physique, un baume au coeur et j'ai les yeux mouillés, rien qu'en regardant les arbres. Ils ont tous leur charme. Et j'aime regarder, à ce temps-ci de l'année , cette vidéo de musique avec un décor coloré. je vous souhaite de faire le plein du beau, pour ensuite mieux vivre le temps gris qui vient. youtube.com/watch?v=6u0DGIh3…
Masks in the hospital: when a patient has to justify wearing one, and a healthcare worker is so wary of a masked person that she asks for reassurance that they aren’t contagious.
A personal anecdote: Yesterday, I had a long, five-hour appointment at the hospital for imaging prescribed by Dr. Piché, a physician and long-COVID researcher, to investigate a potential diagnosis of gastroparesis.
They took images every hour after I ate a radioactive meal.
I was wearing an N95 mask. The technician asked me why I was wearing one.
Feeling a bit uncomfortable having to justify myself, I replied, "I’m susceptible to infections."
She said, "Oh, okay I just wanted to make sure you weren't sick."
I answered, "I’m not sick precisely because I’m wearing a mask."
It was a way to end the conversation and perhaps prompt her to reflect on the fact that she might want to be more concerned about the patients who aren'twearing masks at all…
Because that’s exactly what’s happening, it’s completely backwards. In a hospital, a place where infectious agents circulate, it’s the person taking steps to protect themselves who has to explain why.
And yet, my N95 protects her, too. If I wear a mask, I’m less likely to transmit anything to her, and she’s less likely to transmit anything to me. It works both ways.
Her response: "Look, I just want to make sure you aren't sick, you know?" As if I hadn't understood. I had understood perfectly well.
It’s this reflex that bothers me: the assumption that a mask equals being sick. One should be able to protect oneself in a hospital without having to reassure anyone else.
Well, that’s just one example, one specific person.
But I know many of you go through this.
Take my partner, for instance: at an event months ago, she ran into an old acquaintance by chance who, pointing a finger at her, rudely asked, "Why are you wearing a mask?" She replied that she wanted to protect me because of long covid, as well as herself so she doesn’t have to cancel her groups in her business. It was an unpleasant experience for her.
After receiving a private message, I realize I may not have expressed myself clearly, so I’d like to clarify what I meant.
When I wrote, “AHAM cannot provide this, given that they only measured the 5Pro at maximum speed,” I simply meant that, as far as I know (and please correct me if I’m mistaken), the CADR currently reported for the AirFanta 5 Pro, as with all AHAM-certified air purifiers, is measured only at the highest speed setting.
Because of this, if we want to give the public more complete information, we need to draw on data from independent reviewers such as HouseFresh and people conducting open-source testing. The more information people have, the better equipped they are to make informed decisions when buying an air purifier.
The good news is that AHAM is currently having constructive discussions about providing more complete noise data and is also considering encouraging manufacturers to have their units tested at lower, quieter settings.
If this becomes standard practice, it will be a real benefit to the public.
To improve air quality, we need competition and more air purifier options, along with more data. There is still a lot of work to do. Maximum-speed CADR is often of limited practical use because that setting is generally too loud for everyday use.
I think things are moving in the right direction. I wonder what the landscape will look like in 5, 10, or 20 years. I certainly hope the public will benefit and be better informed.
I am officially announcing that I will soon be purchasing the AirFanta 5Pro for a series of tests in December. Someone responded to my offer. A true win-win situation!
This will be my 6th testing series since spring 2023 (the last time I set up the chamber was in September 2025).
Here is what I plan to do with the machine:
Since it was officially AHAM-certified as of yesterday, I will start, as I always do, by validating my protocol using reference machines certified (AHAM, Intertek, or Energy Star). If necessary, I will apply a weighting factor. My target is to keep the gap between the reference data and my measurements ideally within 5%. Once validation is complete, I can move forward with testing.
For the 5Pro, I plan to:
-Record the sound at different levels using a Zoom H1 device and analyze the noise spectrum with Audacity.
-Find a speed setting between 35 and 40 dBA max, and measure the CADR (PM 2,5 and PM1 CADR) at that level(s). If time and energy available, I’ll measure CADR at 2 different levels.
Why 35-40 dBA? Because I am particularly interested in multi-unit setups operating under 45 dBA max. This requires installing individual machines that run well below 45 dBA. The lower the noise, the more units can be installed. An approach inspired by the leaders at Clean Air Stars.
The AirFanta 3Pro is one of the best machines on the market in terms of price and CADR-to-dBA ratio at low noise levels. I can't wait to compare the 3Pro with the 5Pro. I'm also looking forward to Housefresh's review. The two tests will be complementary.
Note: Even though AHAM is inherently more reliable than other testers, when comparing the 3Pro and the 5Pro, it is better if both are evaluated by the same tester using the same method. Even if that method is less reliable, it has the advantage of remaining consistent across both machines.
Housefresh will be able to do this since they have already tested the 3Pro. I will be able to do so as well, having already tested the 3Pro, which will allow me to compare my test results side by side. AHAM cannot provide this, given that they only measured the 5Pro at maximum speed. Furthermore, unlike AHAM, both Housefresh and I conduct measurements at quiet speed settings.
P.S. I hope to be able to do this in December. However, due to my health (Long COVID), things can be more challenging at times, and it requires careful planning to stay within my energy envelope. I value reliability, which is why I want to clarify that a December timeline isn't 100% guaranteed.
I’m heading into the woods today for a few days to recharge with the love of my life. Just as we do every year.
I’ll be less present, or away altogether, for the next two weeks.
Next week, I have a medical test at the hospital that will take some time (4–5 hours) and energy. It was ordered more than 18 months ago by Dr. Alain Piché, a physician and long COVID researcher.
There’s no shortage of ventilation projects! This is just a break so I can come back refreshed!
Testing air quality monitors. If the weather cooperates (not too cold) and there’s smog, heading to the international AirNow monitoring station to measure PM2.5 and compare my readings with the station’s as a reference, to estimate the accuracy of the PM sensors.
Measuring the filtration efficiency of my DIY window HRVs during their upcoming maintenance. Recording the sound of my DIY HRVs. And after all that, setting up the test chamber for a sixth round of testing since spring 2023, to test a list of air purifiers at quiet settings.
Bye for now, see you very soon. Take care of yourselves. And above all, breathe good air!
And for those lucky enough to enjoy fall colours like we do here in Quebec, soak them up while they last! It’s magnificent. Every year, I’m still moved by all this beauty.
I am officially announcing that I will soon be purchasing the AirFanta 5Pro for a series of tests in December. Someone responded to my offer. A true win-win situation!
This will be my 6th testing series since spring 2023 (the last time I set up the chamber was in September 2025).
Here is what I plan to do with the machine:
Since it was officially AHAM-certified as of yesterday, I will start, as I always do, by validating my protocol using reference machines certified (AHAM, Intertek, or Energy Star). If necessary, I will apply a weighting factor. My target is to keep the gap between the reference data and my measurements ideally within 5%. Once validation is complete, I can move forward with testing.
For the 5Pro, I plan to:
-Record the sound at different levels using a Zoom H1 device and analyze the noise spectrum with Audacity.
-Find a speed setting between 35 and 40 dBA max, and measure the CADR (PM 2,5 and PM1 CADR) at that level(s). If time and energy available, I’ll measure CADR at 2 different levels.
Why 35-40 dBA? Because I am particularly interested in multi-unit setups operating under 45 dBA max. This requires installing individual machines that run well below 45 dBA. The lower the noise, the more units can be installed. An approach inspired by the leaders at Clean Air Stars.
The AirFanta 3Pro is one of the best machines on the market in terms of price and CADR-to-dBA ratio at low noise levels. I can't wait to compare the 3Pro with the 5Pro. I'm also looking forward to Housefresh's review. The two tests will be complementary.
Note: Even though AHAM is inherently more reliable than other testers, when comparing the 3Pro and the 5Pro, it is better if both are evaluated by the same tester using the same method. Even if that method is less reliable, it has the advantage of remaining consistent across both machines.
Housefresh will be able to do this since they have already tested the 3Pro. I will be able to do so as well, having already tested the 3Pro, which will allow me to compare my test results side by side. AHAM cannot provide this, given that they only measured the 5Pro at maximum speed. Furthermore, unlike AHAM, both Housefresh and I conduct measurements at quiet speed settings.
P.S. I hope to be able to do this in December. However, due to my health (Long COVID), things can be more challenging at times, and it requires careful planning to stay within my energy envelope. I value reliability, which is why I want to clarify that a December timeline isn't 100% guaranteed.
Would you like to buy an AirFanta 5Pro at a discounted price? Special offer for anyone living in the Montreal area.
I am thinking of buying the AirFanta 5Pro to test it in early December, but only if someone commits to buying it after my tests. I can even drop it off at your place by car if you are located within 20 km of me.
It's a great opportunity for you to get this air purifier at a lower cost, and for me to test it at a lower cost. A win-win situation for both of us! Plus, right now there is an additional $75 discount when buying with the promo code AIRFANTA5PRO.
The total price if I order now is 276$CAD before taxes.
I offer you at 175$, no taxes.
If you are interested, send me a DM or an email at [email protected]
AirFanta 3Pro's CADR
@CleanAirStars @DavidElfstrom @robwiss @ThisHouseFresh @Engineer_Wong
I propose clarifying the facts, if you agree that doing so would be helpful.
413 CFM is a figure reported in 3 places to indicate the AirFanta 3Pro's CADR: Housefresh, Clean Air Stars, and the AirFanta 3Pro sales spec sheet.
Housefresh reports an independent test result from Elfstrom and Wissman, who measured a CADR of 413 CFM at 12V (particle size is not specified). We don't know which method was used.
On the Clean Air Stars Excel database, a CADR of 413 CFM is reported. Clean Air Stars states "CADR estimated using air velocity measurements relative to max CADR", but it doesn't specify who performed the test and who estimated the filtration efficiency % to calculate CADR from the measured airflow (CADR=FlowX%efficiency). Was it the same person, or did one person measure airflow while a second person estimated filtration efficiency?
On their website, Clean Air Stars indicates that the particle size for CADR defaults to Smoke CADR.
David Elfstrom mention “I only measured flow (not CADR). Flow was 421 CFM with voltage held at 12.00 by a voltage regulator power supply.”
Nathalie Ventilation retweeted
We just got AHAM certified for it.
Search "AirFanta" on this website to see it.
ahamdir.com/directory
This means its CADR is verified through authoritative third-party testing, with random spot checks conducted annually to ensure that production units continue to meet the certified CADR ratings.
AirFanta 5Pro Officially Launched: Two Years in the Making, Fully Evolved
We are excited to announce the launch of our new air purifier, the AirFanta 5Pro, following two years of design and manufacturing.
The 5Pro has been redesigned based on the structure of the 3Pro, with improvements across the board: it looks better and is easier to install.
In terms of performance, the CADR remains outstanding. Measured in an AHAM-certified laboratory, the results are as follows:
PM2.5: 393 CFM
SMOKE: 379 CFM
DUST: 408 CFM
Pollen: >450 CFM
We are also applying for AHAM and ENERGY STAR certification.
In addition, the 5Pro now features a PM2.5 sensor and display, as well as an Auto mode. When disassembled, it can still fit into a 20-inch suitcase, making it easy to carry and store.
For purchase links and more information, please click the link below:
air-fanta.com/products/airfa…
It is currently available for purchase in the United States, Canada, Europe, the United Kingdom, Australia, and countries across East Asia and Southeast Asia.
Would you like to buy an AirFanta 5Pro at a discounted price? Special offer for anyone living in the Montreal area.
I am thinking of buying the AirFanta 5Pro to test it in early December, but only if someone commits to buying it after my tests. I can even drop it off at your place by car if you are located within 20 km of me.
It's a great opportunity for you to get this air purifier at a lower cost, and for me to test it at a lower cost. A win-win situation for both of us! Plus, right now there is an additional $75 discount when buying with the promo code AIRFANTA5PRO.
The total price if I order now is 276$CAD before taxes.
I offer you at 175$, no taxes.
If you are interested, send me a DM or an email at [email protected]
AirFanta 5Pro Officially Launched: Two Years in the Making, Fully Evolved
We are excited to announce the launch of our new air purifier, the AirFanta 5Pro, following two years of design and manufacturing.
The 5Pro has been redesigned based on the structure of the 3Pro, with improvements across the board: it looks better and is easier to install.
In terms of performance, the CADR remains outstanding. Measured in an AHAM-certified laboratory, the results are as follows:
PM2.5: 393 CFM
SMOKE: 379 CFM
DUST: 408 CFM
Pollen: >450 CFM
We are also applying for AHAM and ENERGY STAR certification.
In addition, the 5Pro now features a PM2.5 sensor and display, as well as an Auto mode. When disassembled, it can still fit into a 20-inch suitcase, making it easy to carry and store.
For purchase links and more information, please click the link below:
air-fanta.com/products/airfa…
It is currently available for purchase in the United States, Canada, Europe, the United Kingdom, Australia, and countries across East Asia and Southeast Asia.
Hospital ER ventilation: CO₂ stayed below 1,000 ppm
I was impressed by the ventilation in the hospital ER where I spent almost 24 hours a few days ago, in the Montreal area, Quebec, Canada.
I never saw CO₂ levels go above 1,000 ppm (with Aranet4), even though the ER was over 100% capacity.
Was that enough to meet ASHRAE 241? Of course not. Based on the 700 ppm benchmark in the table shared by Joey Fox, there was still room for improvement.
But it wasn’t a disaster either. And I think that deserves to be acknowledged, even if we’d like to see better.
I don’t know what it’s like in other hospitals, but I wouldn’t be surprised if many were less well ventilated than the one I went to. I also wouldn’t be surprised to see 2,000 or even 3,000 ppm in some places.
I’m lucky to live near a hospital where, at least during my stay, CO₂ stayed below 1,000 ppm.
And you, have you measured CO2 in an hospital? How was it?
Just ordered a paper copy of Victor Hugo’s “The Last Day of a Condemned Man.” (in french) Reading something written almost 200 years ago and still feeling connected to the author’s empathy. It’s a good reminder of what we share as human beings.
Sudden, new and potentially serious health issues. I’m trying to get a medical assessment. I don’t know how long this will last. I hope it won’t last long.
I need to put my monitor testing projects on hold.
Hope to be back soon.
Update: the short version, and the long version for anyone interested.
The short version
I want to reassure that the danger has passed and that I’ll resume my activities after our getaway to a cabin in the woods, which we planned a month ago. We’re leaving in a few days. I’ll get back to my ventilation projects afterward.
,,,,,
The long version
I think I had a migraine triggered by a virus, but I don’t have a diagnosis yet. A cold sore appeared shortly after I started having painful jolts at the back of my head and ear pain. The migraine lasted more than three days.
My pharmacist prescribed antivirals and advised me to seek medical attention promptly after the jolts became more frequent and intense shortly after I took them. I said I wanted to avoid the ER and would rather monitor things to see whether they improved. He told me to wait 24 hours and, if things weren’t improving, to seek medical attention very quickly because it could be serious.
During all this, I had an unusual memory lapse: I couldn’t remember which toothbrush was mine, the blue one or the pink one. I still don’t remember. My partner told me, “It’s the blue one.” I found it a little worrying that I had forgotten my own toothbrush—the information was completely gone.
Twenty-four hours later, I still had the migraine, and I decided to wait until the following morning. That morning, I thought, wrongly, that the migraine had passed and that “only” a constant, moderately painful headache remained. I thought that, without necessarily calling it an emergency as my pharmacist had, I should see a doctor within a week.
I called my doctor’s office. They asked me questions and said they would call me back. I explained that I wanted an appointment within a week if possible, but that my pharmacist said I should be seen urgently.
Shortly afterward, the jolts returned. I called my doctor’s office again (they hadn’t called me back yet) to explain that the situation had changed, that the jolts were back, and that I wanted to be seen within a week; otherwise, I would try a private clinic.
The receptionist, who apparently hadn’t listened to me, replied, “The doctor said to call if anything changes,” and said they could offer an appointment in a month. But I was calling precisely because something had changed. I said that was too far away and that I would try to get an appointment at a private clinic.
I called a private clinic, and they booked me an appointment two days later. The clinic then called me back, and we eventually agreed that a nurse would call to assess me over the phone.
The nurse called later and said I should go to the hospital ER because it could be shingles or viral encephalitis. I said I would think about it, but I really didn’t feel good about going to the hospital. I could end up waiting 18 hours, and with my long COVID, that puts me at risk of post-exertional malaise. That can also be serious for me and has previously brought on new symptoms that became chronic.
She insisted and also said someone should accompany me so I wouldn’t drive. I was surprised. I explained that I thought it mattered that my pain was improving: the jolts were less intense and less frequent. Maybe I just needed rest to recover. I wanted a regular medical assessment, not an emergency visit.
I thought there was a good chance the hospital would ask what I was doing there. Going to the hospital for this seemed excessive to me. I said I would think about it.
I called my doctor’s office again and reached voicemail. I explained that the private clinic was telling me to go to the hospital ER and asked whether I could have an appointment in the next few days. I waited a few hours without a call back.
Then I received an email from the private clinic. The clinic director had reviewed my situation and agreed with the nurse. They said I should go to the ER and that only a hospital had the equipment needed for those tests.
That convinced me. I printed the email, asked my partner to accompany me, and we went to the hospital.
I showed the email and explained that this was why I was there: I had been told to come, my doctor’s office wasn’t offering an appointment for another month, and the private clinic wouldn’t see me because they believed I needed to be in the ER.
I arrived at the hospital ER early in the evening. I saw a doctor 15 hours later. He ordered a brain CT scan to rule out inflammation, but told me he wasn’t particularly worried. He said it didn’t seem like viral encephalitis at all: if it were, the symptoms would be much more severe and, especially, the headache wouldn’t be improving.
I waited another four hours for the scan. A total of 19 hours at the hospital, sitting upright in a chair. I went to the receptionist and explained that I was reaching my limit. I was very tired and felt weak (had palpitations, felt weak, general malaise). I was worried that a prolonged wait could trigger post-exertional malaise from my long COVID, which was a hight risk for me. I asked whether I would be getting the scan soon.
They said they couldn’t guarantee it wouldn’t take several more hours. And after the scan, I would have to wait again to see the doctor. All of this could easily have meant more than 24 hours sitting in a hospital chair.
I asked whether I could book an appointment for the scan if it wasn’t urgent. They told me that wasn’t possible. They also said that if I wanted to leave, I would have to sign a refusal-of-treatment form.
I signed and left. On my way home, more than 24 hours after my message, my doctor’s office called to offer me an appointment in the next few days.
Everyone has a limit to how long they can wait in a hospital. Some people might leave after 96 hours; others after 12. It depends on our physical condition and the risks we believe we face.
In my case, it felt like being asked to run a marathon to get a scan. A marathon that would certainly leave me more vulnerable and put me at risk of potentially serious post-exertional malaise. I know what a post-exertional malaise is and the possible consequence, after 6 years of long covid. All of that to rule out what the doctor considered a low, but still possible, risk of inflammation in the brain.
I got home at 2 p.m. and ate. I was starving. At 4 p.m., I went to bed for the night. I slept for 12 hours, which did me a world of good.
When my partner woke up, she received a message from her nephew telling her that her 27-year-old godson had been found dead. We quickly left the area and stayed at a hotel.
He died a violent death, possibly a murder made to look like suicide. A police investigation is underway. The day before, he had told his mother that he feared someone would kill him and that he was scared. His mother, my partner’s sister, is devastated.
This whole episode has taken a lot of time and energy from both of us, and we have things to catch up on.
In a few days, we’ll leave as planned for our fall-colour getaway to a cabin in the woods. I love this place, and autumn is my favourite season. Being there, surrounded by all those colours, feels like paradise to me. It’s where I recharge. Nothing planned but rest, contemplate the nature, relax with my love, and maybe a good book (in paper, not numeric).
8 CO₂ Monitors Side by Side | Checking My New AirGradient
I've only had this AirGradient for two days, but so far I'm impressed with its CO₂ readings. When I check the monitors against the Aranet4 a few times during the day, the AirGradient is often the one with the closest reading.
More extensive testing is coming soon. This is just a warm-up. 🙂
CO₂ monitors shown, from left to right, starting with the top row:
Temtop C1, Qingping Air Lite, Aranet4, Temtop M10+, VisiblAir Model C, AirGradient ONE, Qingping Air Monitor Pro 2, Inkbird.
P.S. For those who remember that I received an AirGradient earlier: the first unit was displaying 0 for CO₂, so AirGradient sent me a replacement. This one arrived two days ago.
1/ Are you interested in monitoring VOCs at home, but not quite sure what to make of low-cost TVOC monitors?
They have a reputation for being imperfect and sometimes unreliable. I’ve been using them in my own home for years, and I wanted to see how some of them would actually compare side by side.
So I decided to do a little citizen experiment in my living room. 🙂
I tested 6 consumer TVOC monitor models with two very different pollution events: cigarette smoke and mosquito repellent.
Here’s what happened. 🧵
1/ VOC sensors: too imperfect to be useful?
I think we may be looking at low-cost VOC monitoring backwards.
We already know from decades of indoor air research that our homes contain a complex mixture of gaseous pollutants, some of which can be harmful to health.
We also know that many ordinary indoor activities and products add gases to the air we breathe.
Yet when it comes to actually monitoring those gases, something strange happens.
🧵
18/ So there you go. One little drop in the ocean of what there is to learn about low-cost TVOC sensors. 🙂
Just a small real-world experiment in my living room. I hope it adds something useful to the conversation.
Personally, it made me pretty happy to have more than one sensor at home. If one misses something, there’s a good chance another one will pick it up.
19/ Questions and comments are welcome. I’m always interested in a good discussion and in learning from what others have observed.
Just remember I’m a volunteer doing this in my spare time. I’m happy to discuss, but I won’t spend hours going back and forth on the same point.
Sealioning, elsewhere please. 🙂















