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Lazarus Long Profile picture
@LazarusLong13
Jun 5, 2023 • 13 tweets • 6 min read • Read on X
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H/ T @healthyheating for a VERY cool study!

Robot babies, Covid, and resuspended aerosols!!

Hang onto your nappies, kiddos - it's a good old Tweetorial 🧵 with a pay to play study. So, free!

TLDR? Vacuum your carpets, and run the most air cleaning filtration you can afford Image
"We are perpetually surrounded by a cloud of self-induced resuspended particles, referred to as the".... Pigpen effect (my thread, my word, Pigpen).

It is on the order of smoking in terms of particulate rates emitted. twitter.com/i/web/status/1…
Infants can travel up to 20 football fields during a day, with a path as crazy as a cat zigzagging through a room full of Roombas.

If we can kick up our own dust, you would think infants could. And that's what they set out to measure. twitter.com/i/web/status/1…
That dust cloud is a mix of chemical and biological stuff. Like living and dead microorganisms such as bacteria. Biological excretions like animal and mite allergens.

And PFAs, phthalate plasticizers, and flame retardant.

And might include toxic metals like lead. twitter.com/i/web/status/1…
So, they put together a robot infant and ran her over 12 carpets methodically.

And when I say methodically, I mean it.

In the Methods section, there is a link

(I made the mistake of starting this thread last night. Chuckie, below, made his appearance in a nightmare.) ImageImage
that Adobe Acrobat is not letting me grab from the PDF. So, here is where you can find it.

Aerosol and airborne nerds will want to.....fascinating! Image
When the baby started crawling, there was a significant increase in airborne particle concentrations, right where it would breathe those particles.

1.5 and 4 μm size particles? Possibly bacteria and fungal spores.

>6 μm - thought to be biological in origin.
Now, a truly interesting nugget?

When we walk, our personal cloud gets mixed pretty quickly into the overall room air.

Nobody puts Baby in a corner - but they sure put her into her own little cloud.

Because her crawling is not enough to mix that little cloud of resuspended ImageImage
particles.

Another interesting nugget - older, cheaper carpets, counter-intuitively, might be better for Baby. Image
Finally, were the particles inhaled?

Absolutely - see below.

If SARS-COV-2 was brought in on your shoes? It could be kicked up by the baby. Of course.... Image
the most likely source for those Covid particles are from us breathing them out, and then settling on the floor.

So, how can we help our floors stay cleaner?

Vacuuming, of course, but also by cleaning the air with HEPAs and #CorsiRosenthalBoxes (👇).
I strongly encourage you to go read the study yourself as it is methodically well-done.

And just a darn good read!

Here it is, free. (Click the blue button, "Open", on the right.)

sci-hub.hkvisa.net/10.1021/acs.es…
Oops...forgot to H/T for the gif - thank you!

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More from @LazarusLong13

Lazarus Long Profile picture
Dec 23
Ozone. A pollutant no matter where it is - outdoors or indoors.

#DYK that indoor inhalation is 25% to 60% of total intake? Per Weschler?

iaqscience.lbl.gov/increases-ozone

#DYK that MOST indoor ozone comes from OUTDOORS? Per Weschler?

pmc.ncbi.nlm.nih.gov/articles/PMC16…

Truly worried?

🧵 Accounting for the differences between indoor and outdoor air ozone concentrations, Weschler [6] has estimated that indoor exposures to ozone are typically 45% to 75% of total exposures. Because breathing rates are lower when people are indoors, the indoor inhalation intake of ozone is typically 25% to 60% of total ozone intake. These estimates may be low for the population most affected by ozone—infants, the elderly, and those with respiratory and cardiovascular disease. Consequently, if there is no threshold concentration for the health effects of ozone, or if the threshold is low, roughl...
Although there are indoor sources of ozone, in most buildings indoor ozone has been transported from outdoors (Weschler 2000). Indoor ozone concentrations track outdoor concentrations with a slight time lag that depends on the air exchange rate. Ozone is removed by indoor surfaces as well as by gas-phase reactions, and hence, indoor concentrations tend to be smaller than co-occurring outdoor levels.
If you are TRULY worried, you should be focused on eliminating ozone, right?

You would be slipping into people's threads and sharing these cheap DIY activated carbon builds, right?

Because if you are TRULY concerned about ozone, you would not be slipping into threads of people showing pictures of their new FAR-UVC Torches - for any other reason, but to share the good word that the miniscule ozone generated could be eliminated.

VIRUS and OZONE free air.
Read 8 tweets
Lazarus Long Profile picture
Dec 21
ACH ACPH - Air Exchanges per Hour.

An important topic since way before 2020, but given fresh vigor with our collective interest in clean air. Not just disease free air, but VOC, PFA, microplastic, mold, UFP, PM 1, PM 2.5, etc.

The outside air will infiltrate inside.

🧵
That ☝️picture is not typical.

Typical ACH - there can be general estimates, but every house is different. You can determine your own, as shown by @jljcolorado with help 👇👇. Jump to the section shown 👇.

medium.com/@jjose_19945/h…

The estimator is here
docs.google.com/spreadsheets/u… How to estimate the ventilation rate in practice
I am grateful for input and suggestions on this topic from Andy Persily, Shelly Miller, Dustin Poppendiek, Ty Newell, Rich Corsi, Bill Bahnfleth, and Jeff Siegel.
The thread about that article is here. Some excellent discussion on it by some very good scientists, including those Dr. Jimenez acknowledges. Those folks are also on Xitter.

Read 15 tweets
Lazarus Long Profile picture
Dec 21
Ozone. FAR-UVC. GUV222.

New preprint.

Room with 1.3 ACH (1.3 h-1) (like your home).

1 lamp was good enough to disinfect room. Produced "negligible" ozone. -0.62 ±0.03 ppb

Even with 4x the needed strength? 6.98 ±0.24 ppb. -0.62 ±0.03
We refer to this room as “Room A.” Room A has no window, and is connected via a door to a large, open plan lounge area in the office suite. This Lounge space was used for baseline measurements. The door between Room A and the Lounge was closed during experiments. The air exchange rate in Room A was measured using the CO2 tracer method [33] with portable CO2 sensors (Aranet4) to be 1.3 h-1 (Supplementary Information). Room A and the lounge are carpeted. Room A is equipped with a conference table, a small wooden desk, and chairs. It also has room lighting and a wall-mounted computer monitor. ...
Tests with a single fixture used a Lumenlabs Lumenizer 300 (Lumenlabs, Shanghai, China) and tests with four fixtures used Lumenlabs Zone devices. Each of these fixtures contains three optically filtered KrCl bulbs with a peak emission wavelength of 222 nm. The optical output of a Lumenizer fixture is 55 mW and the optical output of a single Zone fixture is 190 mW. According to the manufacturer, each Lumenizer 300 fixture is capable of disinfecting a 4m x 4m room; therefore, a single Lumenizer 300 unit would be normally deployed for a room the size of Room A in this study. That is to say, th...
The conclusion? One lamp does not impact the air quality.

With 4 times OVERKILL.

Under 10 ppb. Secondary organic aerosols (SOA)? minor increases in particulate matter (16% increase particulate matter, 10 % increase in particle number count). We have observed the effects of far-UVC on indoor ozone and particulate matter under conditions of real-world application in a small conference room with low ventilation. We find that a single Lumenizer 300 far-UVC lamp, specified by the manufacturer to be sufficient for disinfection of the space, does not negatively impact indoor air quality through net generation of O3 or PM under the conditions of our experiment. Far-UVC may be a valuable component of a multilayer approach to reduce the risk of transmission of respiratory viruses, used in combination with ventilation and other interventi...
This was not Nukit's lamp.

But it was the same wavelength.



Context.... chemrxiv.org/engage/chemrxi…The far-UVC average fluence used for the lower-intensity (single lamp) experiments in this study was 0.2 μW cm-2. According to the manufacturer, one lamp is recommended for disinfection of a room the size of Room A. The modelled average fluence and irradiance values are consistent with conditions observed by Eadie et al. in a chamber study to reduce airborne pathogens (S. aureus) by 92% or more [16]. Under these conditions, we did not measure significant changes in ozone level or particulate matter in Room A, despite the relatively low ventilation conditions in the room
Read 5 tweets
Lazarus Long Profile picture
Dec 20
Not sure what is going on with @HealthcareGlob1 - they sure seem to have it out for @NukitToBeSure.

They blocked me after I pointed out that they were incorrect. I could care less about being blocked.

I do care they did not address the issues I raised. 🧵
They retweeted this tweet from DisabledDoctor, which has numerous issues.

1. FARUVC has been safely
& extensively tested on the eyes. There are a rather large number of studies on the topic.

2. FARUVC will not cause AQ issues, besides a Yup. Not even considering the fact that she recommends using her far-UV devices in ways that are possibly unsafe (pointed at face as they are untested on eyes and in poorly ventilated indoor spaces where it is likely it will cause air quality issues leading to or exacerbating respiratory problems). She's harming vulnerable people while profiting off of them and she seems to give no fucks while somehow managing to get people to aggressively support her when she is (fairly) criticized. She's a master manipulator 8:08 AM 11 Sep 29, 2024 7,975 Views
negligible amount of ozone.

But that's not me saying that, but the studies. Two studies in well sealed rooms - about 5 parts per billion, 5 ppb.

If you are in a well sealed room, you would want that window cracked, anyway, right?

If not, and you are In summary, the two published measurements of far-UVC associated ozone in real-world settings, both around 5 ppb, are likely to be upper limits in terms of real-life far-UVC usage; this is both because of the far-UVC doses used in the studies, but also because both rooms were comparatively well sealed (respectively 0.4 and 1.4 ACH, see Table 1), whereas far-UVC will predominantly be used in public indoor spaces, which typically feature higher air-exchange rates.18 Overall it is reasonable to assume that far-UVC-associated ozone levels in real-life settings are extremely unlikely to exceed 1...
Read 13 tweets
Lazarus Long Profile picture
Dec 15
Got HEPAs and or a #CorsiRosenthalBox and still have VOC's?

(New furniture, left over smoke damage, odor, etc)

Welcome to @TheFandelier Quick VOC BUILD!

Goal below.
Slap filter on counter.
Slap fan on filter.
Slap USB adapter on fan.
Go.

/1 TruSens DuPont Odor & VOC Filter with True HEPA for Z-3000 TruSens Air Purifier with SilverStone fan.
THE FILTER.

TruSens DuPont Odor & VOC Filter with True HEPA for Z-3000 TruSens Air Purifier

This filter has more carbon than the others from this brand.

"The filter comes w/foam surrounds that make a seal w table and fan."

UPC is 038576802810

a.co/d/gcKIL5KBrandTruSens MaterialCarbon Fiber MERV Rating16 Compatible DevicesAir Purifier Item Weight1050 Grams UPC038576802810 ODOR & VOC DEFENSE : Activated carbon filter helps combat cooking and cleaning odors, and reduces airborne VOCs such as ammonia, acetone and formaldehyde. True HEPA filter captures common pollutants.
the Odor & VOC carbon drum has 3 layers of carbon
The link above will go dead eventually - that's why I am listing the full name above, so you can search for it.

THE FAN.

Silveratone AP183 140cfm is the one you want. The Silverstone AP 180mm is a great choice for the Maxx Core. It comes in a few flavors with varying price and cfm. They are all very sturdy. AP181 100cfm AP182 167cfm AP183 140cfm AP184 143cfm The 181 is very much slower than the others/cheapest. Get 183 if poss best bang/$
Read 15 tweets
Lazarus Long Profile picture
Dec 14
The CDC decides if you, the other patients, and your HCWs wear surgical masks, N95s, or no masks in hospitals. Where you go to get better, not sicker.

They obey the HICPAC, who voted for NO MASKS - based primarily on one study to justify it.

A 🧵 of an inadvertent giant lie? N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel: A Randomized Clinical Trial
I suspect it's not actually a lie - except it kind of is. You read and decide.

The study is Radonovitch (2019). It was done from 2011-2015.

Back then, most everyone, including the authors 👇, thought respiratory viruses were primarily transmitted by actual large droplets. Respiratory viruses are primarily transmitted by large droplets. Because a fraction of respi- ratory viruses may be transmitted by aerosol, N95 respirators have been presumed to pro- vide better protection than medical masks against viral respiratory infections in health care settings.2 However, definitive evidence of
Design and Oversight This cluster randomized, multicenter, prag- matic effectiveness trial 16 conducted between September 2011 and May 2015, with final fol- low-up on June 28, 2016, compared the effect of N95 respirators, used as recommended dur- ing the 2009 H1N1 pandemic, 13 and medical masks, used as recommended to prevent sea- sonal influenza 17,18 and other viral respiratory infections and illnesses, among HCP.17 The in-
Would N95s really be worth the extra cost, if that was true? (No.)

The study was a massive undertaking. It was done at 137 sites, spread over 7 healthcare systems, 5 states and Washington DC.

The investigators were blinded to who had N95s and who had surgical masks. year of participation. Study intervention sites included outpatient settings at the Children's Hospital Colorado (Aurora), Denver Health Medical Center (Denver, Colorado), Johns Hopkins Health System (Baltimore, Maryland), Michael E. DeBakey Veterans Affairs (VA) Medical Center (Houston, Texas), VA Eastern Colorado Healthcare System (Denver), Washington DC VA Medical Center, and VA New York Harbor Healthcare System (New York). Sample storage and data analysis sites
Read 30 tweets

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