About a year ago I posted results of VOC testing using the MoleKule and the Austin Air HP+ on HVAC-Talk.
Due to a server crash all posts were lost. At the same time I was working with MoleKule on a second round of testing.
I posted a primer on Reddit with a promise to post the latest results to follow. Apologizes for the delay in posting part 2. A number of folks have requested this update both privately and on Redit and HVAC-Talk over the last few months.

This post is intended to stand on its own but part 1 can be found at
https://www.reddit.com/r/molekule/co...ekule_testi_1/

I'm not an Indoor Air Quality (IAQ) professional but I do work in the basic science and engineering fields.
In 2015 I purchased a condo that had serious, elevated VOC issues. After months of floundering and
taking the advice of *professionals* and non-professionals that should have known better, I decided
to take matters in my own hands. I'm going to provide a brief summary of IAQ issues specifically
concerning VOCs to establish a basic understanding.
Hopefully folks that know more can correct, add to, or expand. I'm fond of academic references
and objective research so I'll provide links for folks a deeper look.

I hope folks take the time to read the overview. A lot of misunderstanding abounds and the more
we know the better we can challenge manufacturers and resellers.
I suspect that some of the folks selling these devices donít know near what they think they know.
A good story is easy to believe and retell. The same stories are repeated and myths are propagated.
Here are some resources that offer extended evidence based discussions on all things IAQ:

http://www.iaqa.org/ - Superb resource for everything IAQ including professional online courses
http://indoorairnerd.com/ -

Lawrence Berkeley National Laboratory probably has the largest collections of PHDs actively
involved in IAQ science and research. They provide a lot of information for the public on all things IAQ
https://iaqscience.lbl.gov/

The EPA has tons of useful information:
https://www.epa.gov/sites/production...ng_devices.pdf
https://www.epa.gov/indoor-air-quali...anic-compounds
https://www.epa.gov/indoor-air-quality-iaq

Components of IAQ:
Two major components of IAQ are (1) particulates and (2) VOCs. There are other components
(biologicals-a particulate, radon, CO2, CO, SVOCs, Ozone, Nitrogen and Sulfur compounds and other stuff)
but in my situation and I suspect many others (urban North American primarily)
particulates and VOCs are the major offenders.

Hereís a good overview of all the components of IAQ:
https://buildingscience.com/sites/de...ett_singer.pdf

Particulates
Particulates are objects as small as .001 microns (1micron = 1/millionth of a meter).
This can include both inert and biological (viruses, bacteria, tiny bugs, mold, ect, ) components.
Smaller objects are generally more troublesome for a number of reasons.
This pollution is often referred as PM 2.5 - meaning particles <= 2.5 microns.
Fortunately particulate matter can be easily handled (in indoor urban environments) with HEPA filtration.
For a good overview of residential HEPA devices and particulate issues see:

1. https://thewirecutter.com/reviews/best-air-purifier/

2. https://smartairfilters.com/cn/en/
Great site. Great work. Highly recommend for anything about particulates (not VOCs).
Itís worth taking the time exploring what these folks have done.
My hats off Thomas Talhelm and his associates in Asia. This is capitalism at its best.

3. https://www.engineeringtoolbox.com/p...zes-d_934.html
Great reference for the sizes of various particulates. Fascinating!

A true HEPA filter will trap particles down to .01micron. I use to think the .3microns was
the smallest particle that could be caught by HEPAs, not so.
A .3micron particle is the most difficult particle to trap, not the smallest.
Most folks, even ones that sell HEPA filters are not aware of this.
A good HEPA filter is an amazing device and eliminate of a lot of very small stuff floating in the air.
BUT Ė VOCs are not trapped by HEPA filters

To measure Particulate Levels I use the Dylos meter. Industrial particulate meters are also available,
but the Dylos, imo, provides a very good value. Some of the new batch of MOS semiconductor meters are
rumored to be useful for particulate measurements but I have no experience with these.

What are VOCs:
VOC are organic hydro-carbons in various configurations. Some are established carcinogens
(benzene /formaldehyde and others) and many have established negative biological effects

https://iaqscience.lbl.gov/voc-cancer

How are VOCs quantified:
VOCs can be specified in Parts per Billion (ppb/ppm). Basically take a billion particle sample and count
the VOCs. For instance, if you grab a billion particles from your living room air and determine that
100 of them are formaldehyde you have 100ppb of formaldehyde. .

Another commonly used method is to weight the VOCs in one liter of air. If the VOCs weigh over
400 ng/liter (billionths of a gram) concentrations are higher than recommended.
The higher the number the worse the issue. Iíve had readings over 2500ng/liter.
My impression is that many residences are much higher than suspected.

Note: Often time VOCs are denominated as ug/m^3. This is equivalent to ng/liter.

What instruments are used to measure VOCs?
1. PID (photoionization) meters. These devices can provide a rough estimate of Total VOC Levels (TVOC).
This can be very useful in taking relative readings. This is what I used when testing the
MoleKule. Take a measurement before and after turning on the MoleKule. The absolute readings are not
always accurate or that useful but the relative readings will indicate if a device is having an effect.
These devices will almost always underestimate the true TVOC level due to technical limitations.
Also note only TVOC (total) levels can be determined. PID meters cannot indicate what
the individual components of the VOCs are.
Still this device is invaluable in determining if VOCs are raised and how well remediation techniques are working. For more information see: https://en.wikipedia.org/wiki/Photoionization_detector

Please note that PID meters come in two flavors ppb and ppm. Only ppb devices should be used in residences.
PPM versions do not have the resolution to provide useful data.

I used the ppbRae3000 that I rented from Pine Environmental. Pine Environmental has about many rental outlets in the US.
http://www.pine-environmental.com/locations/

The folks at Pine aim to please and they have assisted in resolving a number of issues I encountered along the way.

If you do rent one of these devices you should verify proper calibration. Send me a PM for details

3. Gas Chromatography/ Mass Spectrometry. This is the gold standard for testing for VOCs. Not only
can accurate TVOC levels be measured but the individual VOC components can be determined.
This process is not difficult. The company providing the analysis sends a sample kit to the end user.
Simple instructions are provided and a sample is returned to the testing lab.
Results are available in about 1 week. Both TVOC levels and individual breakdown of VOCs are provided.
For folks that have a concern I highly recommend using this process at least twice.

Iíve used these two companies:
1. https://homeaircheck.com/products/ Least Expensive.
2.https://www.fikeanalytical.com/ High Quality, recommended

4. Passive technology. This may be the best method for measuring formaldehyde and some other VOCs.
The sample is collected on a passive badge and then analyzed by GC.
https://www.assaytech.com/

5. MOS technology. This semiconductor technology is being sold in a number of low cost units as
VOC detectors. From what Iíve seen, the first generation of these devices are not useful.
Some newer chips are available that show promise. If this approach can be verified
it will be a big boon to the home user. PID meters and Gas Chromatography can be expensive.
If home users have a inexpensive way to test their environments, manufactures will be forced to answer why their devices are ineffective.

An important underappreciated fact about VOCs.
VOCs boil from 120^F to 500^F. Just like taking a hot shower where water molecules *off gas*
when the water is nowhere is near 212^F, VOCs off gas from liquids/solids on the surfaces in your home
Ė that includes walls, floors, plates forks, spoons , ect. If youíve got a VOC problem
youíre not only inhaling them but rubbing them on your skin and swallowing them.
VOCs in the air indicate VOCs on your surfaces. Kind of scary.

Cooler temperatures might reduce odors, but that does not eliminate VOCs. They just condense on your surfaces. An 18^F increase in temperature will double off gassing. If want to shuffle VOC from you living space heat things up and ventilate. This is technique, called a *bake out*, has been studied and verified. See:
https://www.google.com/search?q=bake...hrome&ie=UTF-8

VOC abatement:
Remove the source(s)

Ventilate:

Iíve brought down excess readings on a PID meter to close to zero in minutes by
opening windows/doors and moving air with fans through my condo in a 10 minutes.
The power of ventilation is amazing. Of course they come up (slower) when everything is buttoned up again.

Depending on where you live and time of year this may not be practical due to humidity and temperature concerns

I suspect that installing a mechanical ventilation system like an Ultra-Aire or a ERV/HRV system
would have a huge effect. This is probably the fastest way to treat high VOC levels.
Not the cheapest way or the most efficient. Fresh air is probably the only cure for non-VOCs such as CO2

Adsorption:
These systems sequester the VOCs. Carbon is most commonly used but there are other materials.
These can be incredibly effective. The latest system I worked with is advertised for marijuana growers.
Iíve seen reductions of over 60% in minutes measured with the PID meter. Keep in mind Iím
feeding the PID meter directly out of the exhaust the fan on the carbon canister so it will take a bit longer to filter the air in the room. Hereís the setup I used:

Itís not pretty and itís loud but the results have been impressive
https://tinyurl.com/yalkdpek
https://tinyurl.com/ycfo3x23

The Austin Air device I used previously was impressive at a 25 -30% reduction
but the Terrabloom device was over 2x better at 1/3 the cost.
Keep in mind I donít know how long the Terrabloom device will take to saturate and only activated carbon is used.
Also some folks have noticed a slight odor.

The Austin device has a chemosorptive additive that can permanently trap/degrade some VOCs. There is no additive in the Terrabloom device.

Carbon devices have issues:
1. They will eventually saturate and then can release previously sequestered VOCs Ė not good
2. Carbon is picky Ė Some VOCs are preferred over others. Chemical additives are needed if you wish to trap a wider range of VOCs
3. When temperatures are just moderately increased carbon can desaturate and release previously trapped VOCs
4. Carbon doesnít work well at higher humidity levels.
5. Beware of any device that has less than 5lbs of carbon. Some manufactures add thin carbon filter
to their HEPA devices and claim odor reduction. Be skeptical.
`
Photo Catalytic Oxidation (PCO):
This is the technology that MoleKule and a number of other companies (RGF, AirOsais) use.
High energy photons irradiate a special catalyst material to produce *Oxidizing agents*.
These oxidizing agents (hydroxyls,and other stuff) break the hydrogen/carbons bonds of
VOCs leaving only water and CO2. Of course thatís a best case scenario.
Itís much messier in the real world with partial and incomplete break down products.
Sometimes these breakdown products are worse than the original VOCs.
Some studies have shown increases in formaldehyde, one of the nastier VOCs, as a byproduct of these machines.

Nevertheless, this technology does work and results have been published in hundreds if not thousands of
scientific papers since the 70s. NASA used PCO to deal with increased ethylene produced by the
vegetable gardens in the space shuttle.

Hereís a good, if simplified, discussion of this technology:
http://www.explainthatstuff.com/how-...iers-work.html

Itís interesting to note that the PCO technology discussed in the scientific literature often
differs from the devices sold in the residential markets. Many of these devices produce hydrogen peroxide
that is spewed into the living area. Advantages claimed are that this approach can treat surfaces.
Maybe but Iíve not seen much proof other than the claims of the manufacturers.

To theirr credit, the MoleKule stays true to the classic PCO where all the action happens at the catalyst.

Most of the literature shows PCO technology is effective at VERY high VOC concentrations at the ppm level.
This is much higher than what is typically found in a home. There is not much evidence that PCO is effective at the lower VOCs levels that we are likely to run into.

Hereís a very good recent overview of PCO technology Ė Highly recommended:
https://www.mdpi.com/1420-3049/21/1/56/htm

Non Thermal Plasma (NTP)
This approach uses strong electric fields to produce the same kind of oxidants as
PCO but without the UV light. There are hundreds of scientific papers showing this approach works.
I intend to do some testing with these devices. Most of the discussion in the literature refer to
Dielectric Barrier Discharge tubes to produce strong electrical fields.
At least two companies use this technology for residences

Plasma Air https://plasma-air.com/
AtMosAir http://atmosair.com/
Both these devices look promising and I hope to test soon.

Itís also claimed that this technology will cause smaller particles (VOC?) to attract and
clump together. These larger particles, itís claimed, are heavier and will fall to the floor
or be more likely to be collected in a HEPA filter. Even so you will need to vacuum
often and keep your HEPA running to trap these larger particles. And even if VOC can be
trapped in this manner they are not destroyed and can possibly vaporize again.
Still this is fascinating, but I havenít been able to find much confirming evidence.
If this is true then NTP devices might have a significant advantage. They can reduces VOCs
with oxidizing agents and additional by clumping them together with particulates via ion attraction.

Global Plasma Solutions manufactures a device that claims to produce NTP using needle point
technology. A lot of folks rave about these products but there is not much in the science literature
using this approach. The supporting data that GPS provides on their web site is not clear.
They have info on clearing smoke (particulates not VOCs) from a tiny containers or stopping bread from rotting.
Both impressive demos but these have nothing to do with VOCs.
I look forward to testing GPS products or at least reading about VOC testing using this device Ėeven if its GPS own testing.

Biologicals vs VOCs
Itís much easier to kill a biological than to degrade a VOC. Breaking a few carbon/hydrogen
bonds in a biological can be enough to kill it, but All carbon/hydrogen bonds in a VOC
must be broken to degrade it. Otherwise youíre just left with more VOCs than you started with.
Ergo Ė NTP and PCO devices *might* be very effective for killing biologicals but not so much for for degradingVOCs.

Some notes about the MoleKule device:
1.MoleKule is a variant of PCO called PECO. This is a valid, patented technology developed by real academic scientists.
Hereís a Wikipedia discussion:
https://en.wikipedia.org/wiki/Photoe...ical_oxidation

The claim is that PECO produces more oxidizing agents than standard PCO.

2.The device produces No ozone. Most PCO device produce ozone. Whatís wrong with ozone:
https://cfpub.epa.gov/airnow/index.c...oduphigh.index

3.The device uses UVA photons as opposed to UVC. UVA LEDs can be used instead of UVC bulbs.
This means a much longer life span. No need to replace bulbs every year or so.
Not to mention decreasing performance as the bulbs wear out.

4.MoleKule contracted a professional 3rd party testing and provided all the details.
Unfortunately their testing for VOCs does not relate to real world residences.
See this post on Reddit for details:
https://www.reddit.com/r/molekule/co...voc_reduction/
In short reducing an extremely high concentration of single VOC in a small container to much lower
but still elevated levels does not mimic the environment in our homes

5.My interactions with the folks at MoleKule have been stellar Ėway beyond the best that I
ever expected. I wonít go into details but the engineers and scientists at MoleKule have
devoted significant time and material in attempting to resolve my issues.
These guys are real scientiest that publish in scientific journals.

Testing
I tested 3 devices, two carbon units and the MoleKule using the ppbRAE3000 that I rented
from Pine Environmental. I was confident that the ppbRAE3000 was reliable for relative readings.
I positioned the ppbRAe directly in the exhaust of the carbon and MoleKule units. I tested both side by side
in a number of different locations. I let the MoleKule run for days in different rooms before testing. I also let the MoleKule run for up to 24 hours between test.

Results:
Austin Air HP+ - Measured a 20 Ė 30 percent decrease within minutes
TerraBloom Ė Measured a 60 Ė 70 percent decrease within minutes
MoleKule Ė Never measured any significant reduction under a host of testing conditions

Could I be doing something wrong? Absolutely but for the life of me I can figure out what.
Perhaps the MoleKule needs to run for days or weeks for significant reduction. If thatís true MoleKule should say so.

Recently MoleKule announced that they have new 3rd party VOC testing soon to be released. Maybe that will throw some light on the discrepancies.

Future Plans
Depending on feedback from MoleKule and the results of their forthcoming new data I will do more testing.

Test NTP plasma devices

There are a couple of manufactures that produce devices that look promising. Iíd like to investigate

Investigate the latest generation of MOS sensors. Renting PID meters and repeated GC/MS testing can get expensive. Low cost testing instruments would be a game changer.