What the Science Says: Molekule (PECO) vs Volatile Organic Compounds (VOCs)

A study in the journal Science brought media attention to an air pollutant that often flies under the radar: invisible chemicals in the air known as volatile organic compounds, abbreviated as VOCs. Researchers found that personal care products, like perfume used in the home, could emit as much outdoor air pollution as cars in the form of VOCs!

VOCs are commonly found in homes, contribute to indoor air pollution and may cause harmful health effects if you breathe them in. This is why it was important that the Molekule technology could effectively remove VOCs and that there was credible science to back it up.

In 2015, an independent lab at the University of Minnesota conducted an experiment of the Molekule technology and how well it dealt with VOCs. The results showed that the Molekule PECO technology significantly decreased the concentration of VOCs down to undetectable levels. This article will present what the third-party test results mean and how the Molekule air purifier can help with VOCs in your home. You will also find additional tips for reducing your exposure to these airborne chemicals.

What are volatile organic compounds (VOCs)

VOCs are chemical compounds that are truly “volatile”: they readily enter their gaseous form and escape into the air. They may come from products in your home such as building materials, coatings, cleaning agents and personal care products. One of the most notorious ones, formaldehyde, is a carcinogen and is often found in pressed-wood products, paint and new construction. You can read more about the basics of VOCs in this blog article.

Under the scope: Molekule and independent laboratory testing

For a company established in sound laboratory science, testing the Molekule PECO technology against “challenge” pollutants like VOCs was naturally expected and considered a crucial step before commercialization. However, what often lends scientific credibility to technology like PECO is third-party testing. Molekule asked a third-party laboratory to test the technology, as scientific accountability and credibility rests on whether other scientists, without any affiliation to Molekule, find similar results. Because the company strongly believes in scientific transparency, Molekule chose to publish these independent test results that determined if PECO could remove VOCs from the air.

Behind Molekule’s PECO technology

Research and development of the Molekule technology—Photo Electrochemical Oxidation (PECO)—took over 20 years to complete. Dr. Yogi Goswami originally developed the PECO air purification technology to help with asthma triggers in the air. Dr. Goswami has published articles about PECO in peer-reviewed journals, including an article published in the Journal of Solar Energy Engineering. An eminent solar energy scientist, Dr. Goswami brought his expertise to the world of air purification, which during the 1990s, had not seen much innovation since HEPA filters were developed in the 1940s.

This particular technology that he developed, PECO, was capable of destroying VOCs—something that no other technology could do so efficiently. A predecessor technology, called Photo Catalytic Oxidation (PCO), attempted to destroy VOCs; however, the process was not efficient and could produce ozone, a dangerous byproduct.

Third-party testing: PECO vs. VOCs

After two decades of research and development that began in the 1990s, it was time for a test at an independent laboratory. In 2015, Dr. Bernard Olson, the director of the Particle Calibration Laboratory at the University of Minnesota, conducted a test of the Molekule PECO technology: Could PECO pass the test and destroy VOCs in the air? If so, how well would it work?

Dr. Olson is an expert in aerosol science and often tests air purification technology. His expertise lent itself to designing and setting up the experiment.

Here is what you need to know about the test setup:

  • A closed steel chamber was used for the study, with a circulating fan attached inside.
  • A PECO air purification assembly was placed inside the closed chamber.
  • An empty chamber was used as a control.
  • A HEPA filter was also tested in a chamber under the same conditions.
  • The “challenge” VOC was toluene, which was injected inside each chamber setup.
  • Sensitive lab-grade equipment was used to see if VOCs concentrations went down over a 90-minute time period.

The VOC toluene was chosen because it is often used to make paints, dyes, lacquers and fingernail polish. It can quickly evaporate into the air from these products. A serious health concern is its potential effects on the nervous system. You can read more about it in a public health statement on toluene from the Agency for Toxic Substances and Disease Registry.

PECO air filtration assembly inside a lab test chamber

The PECO air purification assembly placed in a stainless steel test chamber.

Test results: Molekule vs. VOCs vs. HEPA & carbon filtration

Here is what happened during the test:

  • A concentration of 1000 parts per billion (ppb) of toluene was injected into the chamber containing the PECO air purification assembly.
  • Every 15 min, the concentration of toluene was measured over a 90-minute period.
  • The same concentration of toluene was injected into an empty test chamber (as a control), as well as a test chamber containing a HEPA filter.

Molekule & HEPA vs. volatile organic compounds (VOCs)

Here were the results (see Graph 1 below):

  • The PECO technology quickly lowered the concentration of toluene all the way down to undetectable levels over 90 minutes.
  • The HEPA filter did not remove the toluene at any significant level.
Graph showing PECO vs. VOCs as well as control and HEPA filter performance

Graph 1: The concentration of toluene measured over a 90-minute time period. The three lines represent one of the three scenarios in the test chamber: the Control test chamber, the HEPA filter and the PECO technology.

Carbon filtration vs. volatile organic compounds (VOCs)

A separate test of the Molekule technology was conducted by Dr. Olson to see how PECO compared to carbon filtration. In this case, the “challenge” VOC was acetone. Acetone is found in many consumer products like fingernail polish remover, certain detergents or cleansers, particle board and waxes. Because you may find these products in your home, the levels of acetone are usually higher indoors.

Here are the test results of carbon filtration of VOCs (see Graph 2 for reference):

  • Initially, the carbon filter began to reduce the concentration of the VOC, acetone.
  • Once the reduction slowed (meaning the gases had begun to saturate the filter), the test chamber was opened and remained open for 20 minutes. After this influx of fresh air, the concentration of acetone went down to 42 ppb.
  • The chamber door was then shut and sealed. After 30 minutes, the concentration jumped from 42 ppb to 130 ppb. Because the chamber was now sealed, and the concentration of acetone went up, this means that some of the gas escaped the carbon filter surface and went back into the air inside the chamber. This is called “off-gassing.”
  • The phenomenon of “off-gassing” does not occur with the Molekule PECO technology and is a drawback of carbon filters.

Off-gassing: A drawback of carbon filters that was observed during the lab test

The phenomenon of “off-gassing” happens because of the special way that gas molecules interact with carbon. First, you need to understand the process of adsorption, which is different from absorption. Instead of the gases being absorbed by the filter like water in a sponge, the VOCs will stick to, or attach to open sites on the carbon filter surface (without being absorbed inside it). They “adsorb” to the surface without becoming integrated within. The gas molecules actually go from the gas phase to the solid phase when they stick onto the filter.

However, if the environmental conditions change, (such as a change in the temperature or the flow of air around the filter), it is possible that the gas molecules can “unstick” and leave the filter surface (this is called “desorption” when they unstick from the filter). In essence, they are evaporating from the filter surface and going from a solid phase back into the gas phase. In this process, the VOC will go from a higher concentration on the filter, to a lower concentration in the surrounding air. This is because the gases will always want to move toward an equilibrium state, just as you may have learned in science class about the tendency for natural states to reach equilibrium. This is an important phenomenon to watch out for, because it means that it is possible for the gases to escape the filter and be released back into the air. This process can happen on any carbon filter because of how these gases behave.

Graph 2 below illustrates how the carbon filter used during the laboratory testing released the VOC acetone back into the air, which did not and cannot occur with the Molekule PECO technology.

Graph of carbon filtration of the VOC acetone with subsequent off-gassing of the chemical

Graph 2: The carbon filter initially reduced the concentration of the VOC acetone. However, after the chamber was opened for a period of 20 min and then sealed, the concentration went up. This shows “off-gassing”; please see paragraph above.

You can learn everything you need to know about activated carbon filters here. If you would like to understand the deep science behind it, take a look at an article about carbon filtration by Brown (1995), which states the following about the potential for VOCs to desorb from carbon filters or carbon “beds”: “When, however, a saturated [carbon] bed is subjected to a flow of clean air, or if indeed a partly loaded [carbon] bed is subjected to air containing the contaminant at a lower concentration than that with which it was loaded, desorption must be taken into account.” This phenomenon of gases “unsticking” from the filter surface because of a change in environmental conditions in a room can be observed regardless of the type of carbon filter.

What do the test results mean?

The test was performed for three air purification technologies in the test chamber: 1) the Molekule PECO technology, 2) a HEPA filter and 3) a carbon filter.

Here’s what the test results mean:

  • The Molekule PECO technology was the only one out of the three filtration systems to significantly reduce the level of a “challenge” VOC and keep it down to undetectable levels. PECO destroyed the VOC molecules as it was designed to do.
  • The HEPA filter is only designed to filter particles and could not remove VOCs.
  • Though the carbon filter initially reduced the concentration of the VOC acetone, it could not keep the levels down. The filter became saturated and began to “off-gas” or desorb after fresh air was introduced into the test chamber. This is a drawback to carbon filters because they are not designed to permanently remove VOCs like PECO technology.

What do the lab test results mean for real-world conditions?

The Molekule PECO technology destroyed VOCs down to undetectable levels—this shows the power of the technology. The results were conclusive in a lab setting.

So, what do the results mean for VOCs in your home?

It must be said that for any technology to hold scientific credibility, testing must be done in controlled conditions to show whether it works or not. The concentration of toluene or acetone used during the lab testing were much higher than what would be present in a typical home–this was done to see how PECO air purification technology could destroy VOCs in more severe environments than a home. Yet even at lower concentrations, the PECO technology was still able to destroy VOCs. This means the results are translatable to the levels of VOCs that might be in your home.

The conditions presented in the lab are also meant to simulate a real-life situation. When clean air was allowed to enter the chamber with the carbon filter, this simulates a real-world occurrence: Perhaps the heater is turned on and the temperature increases, or wind blows through the home because of an open door or window. The lab testing showed that a change like this could result in a carbon filter releasing VOCs back into the air. In contrast, there is no risk of re-emission of VOCs into the air with the PECO technology, as it permanently removes VOCs from the air by destroying them.

The scientific credibility that lab testing offers generally cannot be replicated in the home with the current consumer-grade VOC sensors on the market today. The lab equipment used in the test was highly sensitive (laboratory-grade) and provides results that are more accurate than consumer-grade, portable sensors. As soon as you enter the real world, conditions become highly variable across different home environments and each test may not translate well to every home. Testing in a home would require controlling the environment with regard to variables like occupancy, air flow, etc. It would also require multiple laboratory-grade sensors and instruments (with careful placement and calibration), as well as an effective control.

Additional, low-cost methods to deal with VOC levels in your home

There are additional ways to reduce the VOC levels that may be in your home. Perhaps the most important way is to make sure to ventilate your home well (such as opening a window) when you use products that could release VOCs, such as cleaning products or paints. You can also limit the use of these products or choose ones that contain lower levels of VOCs (for example, look into paints that are low-VOC or VOC-free).  For other household items like new carpet or furniture, you can try “airing them out” before placing in your home, to allow them to “off-gas” any VOCs.

You may need a more regular, powerful solution to reduce the levels of VOCs in your home. There are low levels of VOCs in every home and because they can be harmful to health and even carcinogenic, it is important to reduce your exposure. If you are considering the Molekule air purifier, you can be confident that the revolutionary PECO technology developed by Dr. Yogi Goswami has been scientifically proven to destroy volatile organic compounds (VOCs) in the air.

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