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

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...

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...

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...

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? 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...

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...

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

🧵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.

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

🧵 1/I'll be opening my private test chamber for air purifiers this summer or early fall (located in the Montreal area, Canada). If you have a machine you consider 'super good' and wish to get a CADR measurement, you can contact me via direct message. I will do my best to consider every request. 👇

i just published the DIY Noise Protocol — A Simplified Method to Measure Sound Power of Air Purifiers and HRVs at Home medium.com/@levangelist...

1/ Just published the full FantaMix Review — as promised after the open-source build guide. A tested, DIY system for HEPA-filtered outdoor air — no ducts, no extraction, and under $200 to build. Perfect timing: wildfire season has started in Canada. 🧵👇

Just published: Build the FantaMix — fresh filtered air at home, no exhaust, under $200. Open-source DIY guide (60 pages, step-by-step). 🧰 HEPA + partial heat recovery medium.com/@levangelist...

🧵1/6 I just published the first look at FantaMix, a DIY system that brings in outdoor HEPA-filtered air — and recovers a bit of heat. It’s simple, low-cost, and works even with tricky window setups.👇

A group of NZ doctors, teachers and others, have written an open letter to the Government requesting C02 monitors, air purifiers, free tests, paid leave and recognition of LongCOVID as an occupational hazard, saying too many are still getting Covid. www.thepost.co.nz/nz-news/3606...

Drying my hair caused PM2.5 levels to spike from 0.1 to 109 µg/m³ in just a few minutes. Indoor air pollution can be surprisingly high without us noticing. You can't fix what you don't measure.

1/3 DIY window air exchanger with HEPA — built while house-sitting for my partner during her trip down south. Not an HRV, just a simple air exchanger — quiet, effective fix (~35 dB) for high CO₂ in a tiny bedroom, for under $100. 3–4h build & install 3-night CO₂ test 1h airflow + sound testing

healthydebate.ca/2025/04/topi... What if we told you a simple metal box could greatly improve global health?

1/ 4 In many living spaces, my first advice is simple: Get an air quality monitor (CO₂, TVOCs, PM2.5, humidity). Because as one study said: when we monitor, we start to “see” the air. That alone motivates action. www.lse.ac.uk/granthaminst...

🧪 New test published. I reviewed the Purifresh — a compact window-mounted energy recovery ventilator (ERV). Includes real-world data, airflow tests, noise measurements, use cases, and personal verdict. 👉 medium.com/@levangelist... #airquality #ventilation #HRV #ERV

Just released a Purifresh ERV Review — a window-mounted air exchanger I tested at home. medium.com/@levangelist...

I have long COVID, and two physiotherapists assigned to my rehabilitation—despite being trained in long COVID and seeing me wear a mask—chose not to wear one themselves.

There is an urgent need for the industry to develop more independent testing and rigorous certifications for carbon filters, enabling consumers to make truly informed choices, protecting both their respiratory health and their wallets against unverified marketing promises.

Manifesto for Uncompromising Ventilation Why and How I Commit to Universal Clean Air medium.com/@levangelist...

1/ There’s been a lot of talk lately about activated carbon (AC) filters. 🧵 I’m resharing this excellent article by ventilation engineer Joey Fox. It really puts things in perspective itsairborne.com/intro-to-act...

What’s the Deal with HRVs? Do I Really Need One? This article is the first in a series announced in “HRVs Without Ducts for Everyone: Announcing an Upcoming Series on Testing and Reviews.” medium.com/@levangelist...

A New Children’s Book Empowers Young Readers to Breathe Clean Indoor Air Nicholas isn’t your average kid. He has a unique superpower: he can see invisible air pollution. When Nicholas notices these harmful particles making his classmates sick, he knows he must take action. But how can you fight…

HRVs Without Ducts for Everyone: Announcing an Upcoming Series on Testing and Reviews Did you think installing an air exchanger was complicated or only for homes with ducts? Think again! medium.com/@levangelist...

Tout ce que Trump fait «correspond à une définition de coup d’État», selon le professeur titulaire à la Faculté de droit de l’Université Laval Louis-Philippe Lampron. Je l’ai reçu en entrevue à @noovo.info ⬇️

Des fois, je retourne sur X pour voir ce qui s'y dit. Pis cette fois, je constate que "Reg" m'a démasqué. J'espère que cette enquête sera publique, question que moi aussi, je puisse sachoir ce que je suis réellement. Merci Reg!

Trump, le bandit, profite de la situation pour voler l'Ukraine

A DIY Ventilation Solution for Renters Renting an apartment often means limited control over modifications, especially when it comes to essential systems like ventilation. Poor indoor air quality can significantly impact health and well-being, but drilling holes for traditional ventilation systems…

The Nukit Lantern has passed UL 2998- Zero Ozone Emissions from Air Cleaners Environmental Claim Validation: ul.com/services/zer... cdn.shopify.com/s/files/1/08... We are also now an EPA-registered facility: cdn.shopify.com/s/files/1/08... Reposts appreciated🙂

ERV Purifresh – Tests Coming Very Soon www.purifresh.com/erv.html I just received the delivery of the ERV Purifresh. Excited to test it in the coming days. I will compare it with my two DIY HRVs. First impressions and quick observations 🧵

I've published on Medium "How I Built Two DIY Heat Recovery Ventilators (HRVs)" medium.com/its-airborne... I share the details of how I built my own DIY Heat Recovery Ventilators (HRVs)

The Challenge of Finding Clear and Honest Specs on Air Purifiers and Air Exchangers medium.com/@levangelist...

DIY HRV comparison: I've built 2 DIY air exchangers and compared them to similar commercial models (Purifresh and Accurasee). The performance is impressive

Hands up if your workplace fulfils these criteria? legal123.com.au/how-to-guide...