ACH is in reference to ventilation(outdoor air) where as eACH is equivalent air charges per hour, meaning that filters provide a particle free air flow equivalent.

There is a limit you can achieve using just air filters, getting 16eACH in a large room requires massive amount of air movement, enough that therma comfort becomes an issue. However using 8eACH via air cleansing and 8eACH via GUV is possible. Complementary tech. GUV can also be cheap too.

Also if you distribute them throughout the house, that air movement can actually be cleaned along its way. I achieved a 90+% reduction in PM2.5 and UFP in my upstairs when all the PAC are active in my house. Done during winter so stack effect drives air around,gets cleaned as it goes room to room

We need to do air filtration for PM2.5 and other contaminates, but when stacked with GUV I think we have a path the end of many airborne diseases. Great work by @donmilton.bsky.social in helping other learn more about it.

Haha...somehow I also say "Wow, this takes a long-ass time" even after all these videos I have made. Like how long can a 5 minute video really take? (It took 4 hours 😄)

We made it easy to use the OpenCPC, and how better to show it than via a video. Funny how in the last 5 years I have made more videos than the previous 35 years of my life combined. 😄

It's not always easy to explain how we simplified CPC's, but I think this image really makes the case on how we re-invisioned what the optical counter within the CPC could be.

Hope everyone enjoyed their Halloween weekend! Here at the OpenAeros offices, everyday is spooky season. 👹🎃💆‍♂️

@mfrumholtz.bsky.social just listened to you on the Wedge Live podcast. There were a few misstatements about air pollution that I think are relevant to the discussion. If you would like to chat about them and connect just let me know.

What is your username on X? I am not using it anymore so have a long list of unread DM's.

Thank you for sharing (and registering too)!

If the timezone makes it difficult to attend live, do register so we can let you know as soon as the recording is up.

The @saferairproject.bsky.social is hosting an amazing event on why IAQ matters, IAQ performance standards and policy discussions. If you are in AUS a must attend. Livestream option (hybrid) and recording afterwords.

Just registered myself, should be great!

Register here -->https://bit.ly/ssa-2025

OpenRespirator Creative Cohort: Live Meeting 1 YouTube video by OpenAeros

Miss our first OpenRespirator Creative Cohort Live meeting? No worries, we've posted our discussion here! Get to know our cohorts, get read-in on their efforts and progress, and see some early designs. youtu.be/C0Q0ZH6e5AA

A black and white rasterized laptop and hand holding a pen are pictured. The pen is aimed at the screen of the laptop, which appears blue with a white graphic of a mask on it. The thumbnail of the hand is painted the same blue and squiggly action lines emanate from it. Down the center of the image, weaving in and out of those graphics, appear the words "follow along" in various shades of blue. Underneath, the url openaeros.com/openrespirator is visible. An openRespirator logo with the words "creative cohort" appear in the top right.

This year, we’ve been working with a team of passionate, creative makers to put our open source respirator prototype manufacturing methods to the test. We’re so excited to be introducing you to a couple of them this week. In the meantime, here’s some background on what we’ve been up to: (1/4)

People in conference room at the UN building

The global pledge for healthy indoor air: That clean indoor air is a fundamental human right for protecting health and safeguarding well-being

The momentum for clean indoor air continues to build. I attended the inaugural High-Level Side Event on indoor air quality at the UN General Assembly yesterday. Short remarks by Lidia Morawska @joeallenjoe.bsky.social @isiaq.bsky.social Pres. Kerry Kinney, ASHRAE, WHO, UNEP, many others.

Aaron (and our little CPC! 🥹) are taking their places on the floor of the UN! This year is the inaugural General Assembly High Level Side Event on Indoor Air Quality and we're so excited to participate.

The panel will open soon, watch along here: webtv.un.org/en/asset/k1v...

#IndoorAir

Glad to bring the "little CPC that could" to the Healthy Indoor Air event at the UN today. The conversation in clean air are moving in the right directions.

Open source hardware will be part of the solutions and proud to show off the OpenCPC as part of tools that can help us measure it.

Doh...forgot to attach my picture!

Healthy Indoor Air: A Global Call to Action Join global leaders, policymakers, scientists and health experts for Healthy Indoor Air: A Global Call to Action – the inaugural High-Level Side Event on indoor air quality, to take place on the sidel...

An early AM flight to NYC to join the Healthy Indoor Air event at the UN tomorrow. This is an important step in the process of helping get clean air legislation. You can watch it live tomorrow between 3:30 - 5:30PM ET.
webtv.un.org/en/asset/k1v...

We are limited by budget, so these units will add about 1.5-2.5 eACH to the space, or effectively mitigate about 7 kids worth per classroom. It isn't perfect and with double the budget I think we could hit close to ASHREA 241 levels with current HVAC system.

Clean air is not complicated, and costs less than $10 per kid per year to do. This is the 4th year of managing this for my son's school. What happens when he moves to the next school, who will keep doing this for the other kids? We need clean air standards and legislation.

Passionate about clean air, environmental justice, and community-based participatory research? The OSLUV Project(501c3 non-profit) is hiring for a Grant Project Manager position for a state funded air quality research effort. You also get to work with me 😂
www.linkedin.com/jobs/view/43...

I couldn't think of a better way to have spent the last 2.5 years of my life. I am incredibly proud of what the team at @openaeros.bsky.social was able to accomplish. There were many who said this was impossible, but we did the impossible and this is just the start. 😁

#cleanairisahumanright

Have not tested them, but in general in 2025 if it's not tested against a respirator standard (N95, FFP2, KN95) then likely device can't meet those performance specs. Their website doesn't list any mask standards it complies to but claims a general "95%" which to me is a red flag.

As I understand it yes, of course all the data is animal models but most experiments outcomes are not infection but death. Lower dose reduces probability of death in animals.
qmrawiki.org/experiments/...

So lower dose, in my opinion is always better. But we also need built enviro to have Ro < 1 too

Ahh...yes but this is where it gets interesting. At low risk levels it becomes basically linear(meaning half dose results in half risk). However if the curve is not exponential reducing dose by half could be actually 1/4 risk. Which means are targeted vent+filter targets are easier to meet.

[3/3] Charles Haas has had some good publications on this in the water-borne front. Anyways didn't catch this in the video, and thought it might relevent, and thanks for making the videos!
academic.oup.com/aje/article-...

[2/3] ...it's impossible to breathe in less than 1 virus, it's either 0 or 1. We also have very little data at low dose exposure as to what curve we should use, because it requires tons of data to resolve a 10% chance of infection. So care must be used when trying to estimate below a 1% risk IMO.

[1/3]I think it's also important to note the Wells-Riley model uses a exponential dose-response model(hence 1-exp()). Using it for very-low exposure begins to separate from the physical result. Such that breathing in dose that low enough to represent 0.1 viruses still has prob infection but...

Wildfire Fighters, Unmasked in Toxic Smoke, Are Getting Sick and Dying

It's crazy to me to see the US Forest Service deny the ever obvious health risks with breathing wildfire smoke. We lack good PPE because there is a limited market, it's a limited market because the Forest Service denies there is a problem. Need a demand pull for PPE.
www.nytimes.com/2025/08/17/u...