No one guesses if their kid has a fever
— they measure it.
Indoor air quality deserves the same
Low Cost Sensors are becoming accessible to more families

Why MERV 13 Filters   Don’t Become HEPA at Low Velocity In the DIY air purifier community, a bold theory circulates: sufficiently reducing air velocity through MERV 13 filters would achieve…

In the DIY air purifier community, a bold theory circulates: sufficiently reducing air velocity through MERV 13 filters would achieve filtration rates close to 100%, comparable to HEPA filters.
Why MERV 13 Filters
Don’t Become HEPA at Low Velocity
medium.com/@levangelist...

V-Plex air purifiers — DIY purifiers with internal V-shaped filters — are gaining popularity. But two important issues are often overlooked: sacrificed internal volume (the transition chamber) and uncertain airflow paths.
medium.com/@levangelist...

Estimating CADR with an anemometer is often misleading  It’s better to measure than to guess The Clean Air Delivery Rate (CADR) is a key metric for evaluating the effectiveness of an air purifier. It combines the airflow rate (in…

If you truly want to know an air purifier CADR, it’s better to measure it in a test chamber. This method is far more reliable than estimation using an anemometer — especially when using filters that haven’t been independently tested or have shown disappointing results.
medium.com/@levangelist...

Thanks very much for that letter

Merci beaucoup pour votre lettre, j'espère que ça va influencer, mettre de la pression

Text-based graphic with a navy blue background, a scattering of slightly lighter blue dots, and the Canadian Covid Society logo centred at the bottom. The text on the image reads: “There is no path to a health economy without a healthy public and investment in science.”

We’ve co-signed @Protectbc.bsky.social’s open letter to Prime Minister @mark-carney.bsky.social‬, outlining opportunities to prevent Covid-19 and other airborne health risks (e.g., measles, wildfire smoke) and invest in long Covid research.
covidsociety.ca/news/open-le...

Cat Allergens, Smoke, Dust… the Filter Doesn’t Care: Only Particle Size Matters

TL;DR: Asking “What air purifier is best for cat allergens?” is like asking “What car is best for carrying computer equipment?” You’re missing the point entirely. Filters don’t care what they’re capturing — only particle size matters.

medium.com/@levangelist...

Do We Give Startups A Free Pass On Ethical Behavior? We increasingly want companies to not only deliver great products and services but to do so in an ethical way, but new research suggests that we don't hold startups to the same high standards.

Do We Give Startups A Free Pass On Ethical Behavior?

Startups tended to benefit from a kind of halo effect, where their transgressions were viewed more charitably than those of the larger firms.
www.forbes.com/sites/adigas...

Introducing FantaMix: An Innovative DIY Ventilation Solution At See The Air, I am always excited to share innovative approaches to improving indoor air quality. Today, I am highlighting some fantastic articles by Nathalie Roussy that delve into the world of …

At See The Air, I am always excited to share innovative approaches to improving indoor air quality. Today, I am highlighting some fantastic articles by Nathalie Roussy that delve into the world of DIY ventilation with her in-depth work on the FantaMix.
seetheair.org/2025/07/10/i...

Thanks a lot, Sotirios! I’m glad to see the FantaMix shared — I hope it can inspire others and spark more ideas around ventilation, DIY or commercial.

don't know but i i use personnaly Temtop M10+, Temtop M10 and Temtop LKC-1000s

it was such a great article from Jessica Wildfire. I remember, i've read it a couple of times.

AccordFlow: a quiet, filtered DIY HRV — guide to building it This text is part of a series of articles dedicated to ductless HRVs.

Open-source DIY quiet HRV for apartments — under $300 with a MERV13 filter.
No ads, no paywall.
Guide here: medium.com/@levangelist...
#DIY #Ventilation #MERV13 #AirQuality #OpenSource

10/Let’s stay vigilant: our sector is not immune to its own "Elizabeth Holmes" if we don’t practice discernment. Demand the truth, support #Transparency, and the courage to question. The air we breathe depends on it. #AirQuality #Ethics #Vigilance

9/In the open-source ventilation world, significant safety concerns have already been overlooked due to the enthusiasm for popular solutions. Vigilance and questioning are essential, even in the most trusted initiatives.

8/In the field of ventilation, applying these principles is crucial. The "Manifesto for Ventilation Without Compromise" outlines the commitment to transparency, integrity, and clarity in ensuring truly clean air for everyone. medium.com/@levangelist...

7/ Erika Cheung actions led to the creation of a crucial initiative: Erika Cheung co-founded "Ethics in Entrepreneurship." The idea? Build a culture of integrity from the foundations, so we don’t repeat the mistakes of the past. ethicsinentrepreneurship.org

6/This is why Erika Cheung's TED Talk, the brave whistleblower from Theranos, resonates so strongly. She emphasizes the vital importance of "speaking up when something is wrong," a value that should be deeply rooted in our corporate culture.

youtube.com/watch?v=vMQlj9

5/ Talking about these doubts takes immense courage. There is immense social pressure to "clap along with the group," to not be the "party pooper" who disrupts collective enthusiasm. But it’s a responsibility we must all take.

4/ Spotting "red flags" is a personal survival instinct. It’s like walking through a jungle: you need to know how to distinguish treasures (edible mushrooms) from dangers (poisonous ones) before consuming. Watch the patterns in the small things; don’t wait for it to become a big issue.

3/The Theranos scandal and Elizabeth Holmes are the extreme example, where the desire to believe trumped reason, allowing doubts and lies to accumulate until implosion. A textbook case of the consequences of silence.

2/ In the world of innovation, there’s a trap: the thirst to believe that a revolutionary product has been created. This admiration can blind us to red flags. Never be blindly confident, even in the presence of the greatest "genius."

🧵Thread on Ethics
1/ Business ethics start from the very beginning.
A startup without ethics will never have any.
Ethics should be a priority and must be reflected in actions.
Beware of the “Fake it until you make it” mentality.

Introduction to Far-UVC and Air Purifiers Using computational modeling to understand how to best use these technologies in the real world The Science Behind the Comparison To understand the differences between Far-UVC and filtration, we need ...

www.nukit222.com/blogs/info/f...

How Much Heat Does Your HRV Really Recover?   A DIY Protocol for Measuring Sensible Heat Recovery This is the protocol I used to measure the percentage of sensible heat recovery of the Purifresh and three DIY HRVs — shared here as an…

I just published on medium
How Much Heat Does Your HRV Really Recover?
A DIY Protocol for Measuring Sensible Heat Recovery
medium.com/@levangelist...

7/Eventually (hopefully this year), I will publish a website where all data from my chamber tests will be freely accessible. We are talking about dozens of different machines and settings – a comprehensive resource for the community!

6/While these tests do not constitute official certification, a CADR calculated in a controlled environment can provide useful data. This is a personal initiative aimed at providing information, driven by an 'open source' spirit of knowledge sharing

5/Please note: my chamber is optimized for CADR up to approximately 500 CFM. For higher capacity machines, I will identify the setting (and associated noise level) that achieves this 500 CFM threshold.

4/ My experience includes testing various popular models with my protocol, such as the Northbox Mini, Tempest, Tempest Euro, AirFanta3Pro, as well as several DIY purifiers I have designed or evaluated.