iiinova — where your digital self keeps evolving

The issue is that there is no industry standard to define "real HEPA". That is the crux of the problem, and it's compounded by the fact that if you you did use "real HEPA" the reported CADR would be lower. It has incentivized manufacturers to claim "HEPA" in some fashion but not actually use it.

040

[2/2] The mechanisms for particles are different and so you can have low PM2.5 and high UFP(roadways), but also high PM2.5 and low UFP(smoke). Things like transport duration, as well as that UFP can agglomerate on to the larger particles all create unique dynamics and why we need to measure both!

0100

[1/2]Nearly 200 ug/m^3 of PM2.5, can anyone guess what the ultrafine particle count(UFP) looks like? About 11,000 p/cm^3 which is normal for this area. WHO suggested guidelines are less than 10,000 so it's not bad. Why might you ask?

3110

I am not defending them, but the definition of HEPA depends where you are. It also depends at what face velocity(flow). Many filters can be "HEPA" at low speeds but at higher fan speeds there is more leakage and it's not "HEPA". Thats why all that matters is CADR, how much clean air.

1111

Ironically commercial air cleaners don't need to use HEPA at all, and shouldn't. All that matters is CADR, which represents the amount of clean air it generates. It's slightly counterintuitive, but a lower filtration filter (95%) in a system actually delivers more clean air.

1131

Optimizing the Design of Room Air Filters for the Removal of Submicrometer Particles

One area we need to see more progress is that the filter doesn't need to be (and shouldn't be) HEPA. All that matters is CADR, and optimal filtration rate is likely ~95%. Stephen Rudnick's paper in AS&T I think makes the best scientific argument. www.tandfonline.com/doi/abs/10.1...

tandfonline.com

Room air filters, which usually closely resemble high-efficiency particulate air (HEPA) filters, should be designed to maximize the clean air delivery rate (CADR) rather than operate at the very hi...

083

Aaron Collins @masknerd.bsky.social · 25/06/2026

This is awesome and stoked that they some serious powerhouses behind the advisory committee (like yourself 😁). Will they have open RFP's or what is the future of the funding methods?

1150

Likely cooking aerosols rapidly discharged the filter. Classic HEPA filters get high filtration from using lots of tiny microfibers, which has the trade off of resistance to airflow. Electrostatic use much lower fiber density, and enhance using static charge for eqv filtration but better airflow

160

[3/3] So this is the challenge with using these filter styles for long duration, you just don't know if they are still working.

2200

[2/3]The issue with electrostatic media, is they can lose their filter performance but still move a ton of air through them. This is contrast to the stock HEPA, in which the unit in the kitchen has noticeably reduced it's flow in about 6 months(which is when I change them).

1190

[1/3] As promised, the results from the long-duration testing of a MPR 2800 filter taped to a Taotronics AP-003. 1.5 years later and we see drop of *~70%* in performance in the 0.3-0.5 um size range from the test when new!!! (Same testing setup but at different times so apx ±10% error)

1265

It's NaCl (8% solution in a TSI 8026, 70-80nm CMD) with an SPS30 using the 0.3-0.5um channel. It's the same sensor used to in the 1st measurement, and also have a control AP003 for this test so can roughly compare apples to apples. One hint is that it's next to my kitchen...

130

Probably the Winix brand, but it includes a "plasma" system which you have to know to not turn on. For sure the AP-003/Lorell were the best value out there.

010

Yes stock filter removed, so all the filtering is by the 3M filter taped to the front

010

This replaced the internal filter, which was removed and the 3M filter taped on the outside. Its getting harder to find the replacement filters for these units so wanted to test it out before I ran out of filters.

250

Aaron Collins @masknerd.bsky.social · 15/05/2026

About 1.5 years ago I taped on a 16x20 3M MPR2800 filter to a Taotronics AP-003. It boosted the CADR by about 20-30%. Let's take some guesses as to what it is a 1.5 years later? You think it's still performing at 90% of where it was, 50%, or 30%? Let's see your guesses! Will post the CADR tomorrow

A white air cleaner with a now darkened air furnace filter taped to the front. It fit closely to the size of the air cleaner. Gray tape is visible. It's placed in a dining room with wood floors, and a carpet visible in the edge of frame.

A close up of very dirty filter, with dust bunnies visible between the tight pleats of the filter. It's dark grey with contrast to the white frame of the filter.

8444

Thank you for the tireless work in this space. When I saw the BMJ article it felt like 2020 all over again. I wish the ship would turn direction a little faster 🤷.

050

Aaron Collins @masknerd.bsky.social · 13/05/2026

What I have found is the issues around long term drift and "auto-calibration". The Senseaire Sunrise in the Aranet is still the best NDIR IMO. Airspot uses the Senserion SCD43 which seems to drift more over time. However I prefer it the most just due to the size and convenience.

0162

Aaron Collins @masknerd.bsky.social · 08/05/2026

Thanks for bringing attention to the issues around UFP's. The crew at @openaeros.bsky.social has launched a much lower cost UFP monitor (called a Condensation Particle Counter) which while not cheap at $4950, is much more accessible than the past.

030

Aaron Collins @masknerd.bsky.social · 05/05/2026

@openaeros.bsky.social trade show booth and bonus poster. It's a great poster, as it highlights that air cleaners are very effective against ultrafine particles (which are tiny) and PM2.5. We don't need anything fancy to start bringing clean air to all. All we need are fan+filter.

Picture of Aaron in a selfie showing the OpenAeros booth with a table. On top of it are two OpenCPC's along with various schwag and demo.

Aaron with an uncomfortably large smile in front of a poster that shows graphs but it's too dark and too small to see

0212

Aaron Collins @masknerd.bsky.social · 04/05/2026

I think those numbers are significantly over estimated. <10um particle deposition to your eyeballs is pretty much nothing, and when compared to lung deposition is trivial. One viable pathway is having someone basically spit in your eye, which can happen but requires some very specific risk scenarios

241

Aaron Collins @masknerd.bsky.social · 04/05/2026

Another flight another...wait no V-flex? I always like the easy wins in terms of reducing risk, but the thermal comfort of this mask has been my go to lately. I haven't posted a lot, but I have rocked this combo for an entire year and my no-COVID streak continues. Off to talk clean air at ASIC LA!

1631822

Aaron Collins @masknerd.bsky.social · 25/04/2026

A simple and well written piece. Perfect is the enemy of good. We have the tools today to clean the air and we should use them. We have PAC's, HVAC, IAQ sensors and even masks. If and when we start running into issues that the air is too clean indoors, well that is a good problem in my book.😁

05514

Aaron Collins @masknerd.bsky.social · 24/01/2026

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.

120

Aaron Collins @masknerd.bsky.social · 24/01/2026

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.

120

Aaron Collins @masknerd.bsky.social · 23/01/2026

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

040

Aaron Collins @masknerd.bsky.social · 21/01/2026

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.

13911

Aaron Collins @masknerd.bsky.social · 05/12/2025

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 😄)

010

Aaron Collins @masknerd.bsky.social · 04/12/2025

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. 😄

1140

Aaron Collins @masknerd.bsky.social · 11/11/2025

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.

0150

Reposted by Aaron Collins

OpenAeros @openaeros.bsky.social · 03/11/2025

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

041

Aaron Collins @masknerd.bsky.social · 02/11/2025

@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.

070

Aaron Collins @masknerd.bsky.social · 01/11/2025

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

110

Reposted by Aaron Collins

The Safer Air Project @saferairproject.bsky.social · 29/10/2025

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.

021

Aaron Collins @masknerd.bsky.social · 29/10/2025

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

4132

Reposted by Aaron Collins

OpenAeros @openaeros.bsky.social · 20/10/2025

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

youtu.be

OpenRespirator Creative Cohort: Live Meeting 1

YouTube video by OpenAeros

031

Reposted by Aaron Collins

OpenAeros @openaeros.bsky.social · 06/10/2025

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)

1134

Reposted by Aaron Collins

Linsey Marr @linseymarr.bsky.social · 24/09/2025

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.

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

39722

Reposted by Aaron Collins

OpenAeros @openaeros.bsky.social · 23/09/2025

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

OpenAeros founder Aaron Collins poses for a selfie from the floor on the UNGA High Level Side Event On Indoor Air Quality with the OpenCPC. The CPC is on, Collins is wearing a mask and suit, and the meeting room behind him is filling with people from across the globe who are convening to discuss IAQ policy.

the OpenCPC sits facing a filling room at the UN General Assembly Side Event on Indoor Air Quality. Its screen displays a live particulate count and the screens labelling participant and audience seats face back, reading #IndoorAir

25413

Aaron Collins @masknerd.bsky.social · 23/09/2025

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.

1728

Doh...forgot to attach my picture!

0300

Healthy Indoor Air: A Global Call to Action

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...

webtv.un.org

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...

1502

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.

0110