Nathalie Ventilation

Where should you carry a CO₂ sensor: in a pants pocket, on your wrist, or in an open bag?
I tested these placements. The results surprised me and left me with more questions than answers.
I’ll share the results, my observations and questions in the replies below

@ARCTIChannel I just sent you an email at sales@arctic.de regarding the possible discontinuation of the P14 Max . I'm tagging you here to increase my chances of receiving a clear and prompt response, as your answer will directly affect my testing plans.
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Manifesto and reflection on my involvement in the air quality field

Why I'm rebuilding my test chamber in December, and what the exchanges around the tweet I'm sharing here are making me think about
This December, I'm starting a new series of chamber tests on DIY air purifiers: CADR, noise, airflow, power consumption, filtration percentage.
I was going to talk about this a bit later, but I'd rather explain it now, because it directly relates to my questions about the AirFanta 3Pro's figures, the subject of the tweet where I tagged several people.
Why did I decide to rebuild my test chamber in 2026?
The reason wasn't very glamorous or exciting. It's about doubts I had regarding a DIY model I had tested : The Owl.
A little detour into the past. In autumn 2024, I had a real "wow" moment with a model I later nicknamed "The Owl." It's very small (11.5 in wide, 7 deep, 15 high), has just one filter, blows upward, and can be placed against a wall or in a corner. My measurements showed a PM1 CADR of 121 CFM at a low setting, at 39.2 dBA at one meter. If those measurements hold up, that would be about 5 ACH in a 180 sq ft bedroom with an 8-foot ceiling.
x.com/VentiloAngel/s…
For a machine this size, one that can be placed against a wall, at this noise level, that's relatively rare. It's exactly the kind of solution I want to offer people who have noise and space constraints. I fell in love with The Owl.

Then I started to doubt. I don't remember what triggered the doubt, but some of my numbers didn't add up, and I could no longer take them for granted. I was disappointed! Which led me to think I needed to test again to verify. Except...
Another small detour to explain.
After my fifth series in October 2025, I had decided to pause testing for at least two years, to organize and share the data I already have. I had done enough for now, for a good while. It's energy-draining and time-consuming. It costs money too.
But I could hardly be comfortable leaving that doubt hanging. So this year, I decided I would rebuild my test chamber. For the sixth time since spring 2023.
It involves a lot: reinstalling the greenhouse in my living room, sealing it to the floor, verifying my protocol with reference devices (AHAM- or Energy Star-certified).
My apartment isn't really an apartment anymore, except my bedroom, which stays the same. I end up almost not seeing my girlfriend during the test series, because I want to limit how long the greenhouse stays open and there's so much work to do. From morning to night, seven days a week, for weeks, to collect data, a pile of data. Numbers in Excel cells.
I rest when I air out the space between tests. Not for long... At least it isn't too physically tiring, but I have to be cognitively present from morning to night.
So I decided I would redo all of it, for what? To risk revising downward the performance of a model I adore. All this work to possibly revise data downward. Not exciting, is it? Well, for me, it's necessary, out of love for data.
Let me open a parenthesis to share some good news: once the greenhouse is set up, adding more tests is easy. So I'll take the opportunity to test new devices, including a DIY air purifier with a carbon filter, and that will be exciting. I can't wait! But without the story with The Owl, I simply wouldn't have done it.
All of this to say that...
It's the same spirit that made me ask my questions about the AirFanta 3Pro. A spirit of open science. Curious. Transparent.
x.com/VentiloAngel/s…
I only wanted to understand who measured what, with which method, and how to link the published numbers to the measurements they come from.
What I'm putting myself through for The Owl is far more work than what I was asking for there: that we sit down and find out what happened with the famous 413 CFM of the AirFanta 3Pro. Measured by whom, and how? 413 CFM is a smoke CADR? Dust CADR?
Unlike The Owl, which is not a commercial product, the AirFanta 3Pro is sold with a spec sheet that advertises 413 CFM. Transparency toward the public seemed important to me, and I hoped an exchange would help clarify this.
This exchange has brought me back to a question I had already been considering about my own work. I built this project partly on the hope of finding people who wanted to examine measurements and resolve discrepancies together.

That hope matters a great deal to me, but it creates no obligation for anyone else. People may have different interests, priorities, or time available, and I cannot infer their commitment to rigor from whether they take part in this particular discussion.
What I’m reconsidering is how much of my own involvement rests on the prospect of that shared exchange, and how I want to shape my work when that exchange does not materialize. Rechecking The Owl remains important to me regardless.
It brings me back to what I hoped for years ago: a community where we examine methods, compare results, and look together for explanations of the gaps, in good faith, staying on substance. I'm not talking about criticizing for the sake of criticizing, or questioning for the sake of questioning.

Another experience made me think. A person wrote to me privately this year to challenge one of my Medium articles. When I asked why they didn't write it publicly, for everyone's benefit, they answered that they didn't want to embarrass me.
But why would a question about my data embarrass me? To assume it would is already to personalize the debate. And that's the opposite of what I'm looking for. The last thing I want is a personalization of public discussion.
I prefer open exchanges: if a piece of data is wrong, every reader of my article should be able to benefit from the correction. Discovering an error may disappoint me and create work for me, but I want to know! Making a mistake shouldn't be associated with embarrassment, but with a desire to improve. To roll up our sleeves. To work to move forward.
And it's in the same spirit that I question other people's data. In the case of the AirFanta 3Pro, it may simply be a misunderstanding waiting to be cleared up by the people involved. I had expected a clarification relatively quickly, because I assumed that curiosity was shared.
Something else I've observed for a few years: "good news" (the glamour, the excitement, the novelty, whatever evokes innovation) and impressive performance circulate easily in public, while doubts and contradictions sometimes stay private or go unanswered.
Why this matters so much to me
For years, I've been accumulating chamber test data with the intention of making it available as open source, in the spirit of what Clean Air Stars has done. I got excited about its database and about the work of Clean Air Kits. They've been true leaders for me and made me want to contribute in turn, with my modest means.
My goal, once everything is finished and published, is that people can use my data to shop for an air purifier to build or buy, comparing according to their needs: dozens of DIY purifier combinations, measurements of noise, performance, footprint, and power consumption.
I also want to offer noise calculators to estimate the total sound level of a multi-unit setup. People will use these numbers to calculate, buy, and plan real installations. Accuracy therefore has a very concrete use.
Beyond my passion for ventilation, my love of data, rigor, and scientific exchange matter even more to me. It's also on this hope of a shared interest that I built my project. For years.
How much is the Clean Air Stars database appreciated and used? How much do we value data accuracy? And what place do we give to the exchanges needed to understand what doesn't add up? I don’t have the answers of these questions.
And now?
I've been questioning for a while the energy I put into this work (a hobby I’m passionate abou) but one that, yes, is work, especially when I'm in the test chamber). This lack of discussion simply adds weight to the question.
I can't infer the interest of an entire community from a few exchanges that went unanswered. But it echoes other observations and makes me consider redefining my involvement. I wonder to what extent the community of scientific exchange I hoped for is possible, and to what extent I'm pursuing an ideal I’m still trying to find a shared space for.
I will probably finish what I've started over the coming years: compile all the information, as Clean Air Stars did, and offer a noise calculation tool for multi-unit setups.
After that, possibly stop these activities, once I've made this gift to the community. I still wonder about the interest this gift will generate.
I'm reflecting on the meaning of my involvement.

Star Trek: The Next Generation is one of my all-time favorite series because of the values it represents. And yes, Captain Picard was my favorite character. When I was younger, I even dared to answer "Captain Picard" during a job interview when asked who I admired. Yes, I actually did that! I see the ship and Starfleet headquarters as embodying a kind of galactic Charter of Rights and Freedoms. You can truly trust the hierarchy because you know that no one is abusing their position. The lowest-ranking person on the ladder can spot an anomaly and report it to their immediate supervisor, knowing for sure it will be passed up the chain to the captain that very day if necessary. The captain listens to his entire team and trusts their expertise, but in the end, he has the courage to make difficult decisions entirely on his own. What I also loved about the series is how it made me dream of a better world, one with more collaboration and less competition. A world where people respect their leader, and the leader respects his crew. Where everyone knows their role. And finally, I love the idea that on this ship, if they learn that a planet in another galaxy needs help, they won't hesitate to step up and lend a hand. Mutual aid, collaboration, curiosity, personal growth, stoicism, science, rationalism, and humanity. And as one of my favorite authors puts it, rationalism is humanism, and rationalism is universalist.

Bon voyage, mon capitaine!

Good Halloween!