Molekule PECO Air Purification Technology: Tool to Help Address Indoor Viral Exposure Concerns.

Featured Article , AIR 2022 , Issue 1 , Article 3

Ishneet Kaur , Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University Chandigarh, 160014, India.

Perspective: Can chemistry save humankind?

Wouldn’t it be great if the air you inhale is free from all viruses, bacteria, and other pollutants?The answer is loud-YES! It would be the biggest asset in the current situation. Before getting into the project on air purification, I conducted a small survey in which I collected the data from my family, neighbors, and the people I was in contact with, so around 72 people were asked an appealing question, what do they want science to give them? And I was intrigued to know that about 89% of people wanted cleaner air to breathe in.

In the present climate, pollution is a sizable issue and a matter of distress among all and sundry. So, let’s dive into this article with full vigor and see what maneuvers have been taken and what can be further done to intercept the situation. Pollution is the introduction of noxious materials into the environment, and these materials are called pollutants. Air pollution is the cause of various diseases, including, Leukemia – a type of blood cancer usually associated with exposure to benzene vapors (through inhalation), Chronic Obstructive Pulmonary Disease, Neurobehavioral disorders – neurological problems, and developmental deficits due to air toxins such as mercury (which is the only volatile metal). Therefore, removing these pollutants is an instrumental task to be accomplished.

Sensing is one of the most cardinal parts from the environmental and toxicological viewpoint. Although different detection methods are being applied, including HPLC, GC, and MS, these aren’t suitable for in situ detection due to their cumbersome operation. Alternatively, sensors, due to their high sensitivity, easy operation, high selectivity, cost-effectiveness, and the most vital: portability, are best suited for in situ detections of air-borne pollutants. Additionally, the strengthening in automation, miniaturization, and the development in high throughput detection conform to the trend of future sensing [1]. Moreover, due to the complex structure and toxic functionalization of pollutants, it is pretty taxing to axe these contaminants via physical, chemical, and biological processes since they are limited to certain limits such as pH, solubility, and favorable conditions. Adding to it, high cost and high energy demands; pose a barrier for the usage of these processes. Hence, several methods such as biomass, biosorption, photocatalysis, and membrane filtration have been devised. Out of all these methods, photocatalysis is the loftier one. Photocatalysis is carried out under the influence of visible or UV light depending upon the bandgap of the used materials, including photocatalytic nanoparticles. Every research worker aims to carry out reactions in visible light since the sunlight spectrum constitutes around 40% of it [2]. To embark on, the first and foremost task is the detection of pollutants because until and unless sensing isn’t done, there is no gusto for degradation. A very conspicuous question might arise in your mind: which material will be best suited for photocatalysis?

So, it was in 1938 when Goodeve and Kitchener unearthed that TiO2, a highly stable as well as non-toxic oxide when exposed to oxygen, acted as a photosensitizer for bleaching dyes, as ultraviolet light absorbed by TiO2 led to the production of active oxygen species on its surface, resulting in the blotching of organic chemicals via photooxidation [3]. Since then, several advancements have been made, and many materials have been synthesized to serve our purpose. I’ll be citing some of the articles which have paved the way to creating some very superlative materials.

Firstly, three methods, namely: chemical precipitation, hydrothermal method, and microwave irradiation, were employed for obtaining different morphologies of CuO nanomaterials and were tested for antimicrobial activity by Chauhan et. They observed that CuO nanoparticles prepared by chemical precipitation were highly effective in antimicrobial activity and depicted excellent chemical stability [4]. A minor extension to it, wherein a nanocomposite while, a-Bi2O3– ZnO synthesis by facile, cost-effective, ultrasound aided precipitation followed by hydrothermal growth depicted 100% photocatalytic activity may be due to lower recombination rate of electrons and holes. Adding to it, the composite showed magnificent antimicrobial activity against human pathogenic bacteria (S. aureus) with a 1.5 cm zone of inhibition for 1 mg L-1 dose by employing a well diffusion method. The composite exhibited excellent stability with a meager loss in the degradation efficacy even at the end of the fourth cycle and thus showcasing recyclability. Therefore, this heterostructure nanocomposite appears to be a promising material for umpteen number of environmental remediation applications [5]. 

Wright et al. demonstrated antibacterial and antiviral activity by coating the surface of textiles with siloxane copolymer using room temperature procedure. Sacrificial porphyrin generates reactive oxygen species resulting in cross-linking of amine-containing polysiloxane. Antimicrobial activity was illustrated using green lights, and inactivation (>98%) was observed. Likewise, antiviral activity owing to SARS-CoV-2 resulted in a 90% decrease in virus concentration on fiber coated with photoactivated polymer. Thereby, the use of treated masks will further reduce the spread of the virus as it will be destroyed on the surface of the mask. This, moreover, is anticipated to show antiviral activity and various applications against influenza and other viruses [6].

Probing further, in a plug flow experimental setup, a coating containing C-TiO2 in powder form and a suspension form on acrylic top was explained by Lorencik et al. for evaluation of indoor air quality and purification. The latter showed better visual properties and excellent photocatalytic activity after pre-treatment. This study, however, reveals that a better coating should be employed, such as photocatalytic wallpaper coating for prediction of real performance and employing a lower flow rate (<1L/min), lower concentration of inorganic and organic pollutants (ppb), and lower visible light intensity as their samples manifested, 7% de-NOx efficiency after a 5 h UV pre-treatment and 18% after a 10 h UV pre-treatment for coatings containing 30% of C–TiO2 [7].

Seeing that a plethora of advances can be carried out, I chose to work on this very topic of air purification. During this work, an event was held on 3 October 2021; a webinar entitled “Molekule PECO air purification technology: Tool to Address Indoor Microbial Exposure Concern” was organized as a joint venture of SAIF, PUC (Sophisticated Analytical Instrumentation Faculty) Panjab University, ASIRE (Academy of Scientists for Industrial Research and Education), Molekule, USA and PGIMER (Postgraduate Institute of Medical Education and Research) Chandigarh. It was Chapter 2 of the indoor air webinar series ‘An initiative of ASIRE.’ The event’s primary purpose was to bring indoor microbial exposure and its impact on health and broach the benefits and applicability of MOLEKULE AIR PURIFIER that uses the PECO process. The event aimed at making the participants, especially doctors and medical practitioners, learn the byzantine chemistry behind the purifier in an explicit form and how its use could benefit hospitals, patients, doctors, and hospital staff.

The panel members were cognitive people who could delineate the components and statistics conducted of the air purification technologies. It was an honor to have Hon’ble Governor of Chhattisgarh, Sushri Anusuiya Uikey, Vice-chancellor of Panjab University, Prof. Raj Kumar, and President of Florida Polytechnic University, Dr. Randy Avent, among the panelists for this webinar.

The other panelists included:

  • Dr. Jaspreet Dhau, Senior Director & Head of R&D, Molekule Inc. USA
  • Dr. Rahul Mahaskar, Director, College of Medicine Office, USF, Tampa
  • Dr. Ajeet Kaushik, Secretary, Academy of Scientists for Industrial Research and Education
  • Prof. Hemant Batra, Director, Principal of Institute of Dental Sciences and Hospital
  • Dr. Varinder Garg, PGIMER, Chandigarh
  • Mr. Karan Khemka, Indian Manager, Molekule Inc. USA
  • Prof. Ganga Ram Chaudhary, Director, SAIF, Panjab University, Chandigarh
  • Dr. Rajeev Answal, Department of Physics, Panjab University, Chandigarh
  • Dr. Siddappa Byrareddy, Professor Department of Pharmacology & Experimental Neuroscience University of Nebraska Medical Centre

Prof. Raj Kumar (VC, PUC) welcomed the Hon’ble governor of Chhattisgarh, Sushri Anusiyyya Uikey, who congratulated the organizers and expressed profound gratitude for reaching tribal states and lauded the efforts of Dr. Jaspreet Dhau for ensuring reverse brain drain. Dr. Anthony S. Billups gave an overview of the perspectives and benefits of purifiers relating to commoners, doctors, and patients. While mentioning their prime mission, “Deliver clean air to everyone, everywhere,” Dr. Jaspreet Dhau sustained to the topic why do we need clean indoor air? Talking about the stats, he brought up an eye-opening fact that around 4.2 million premature deaths happen every year solely because of taint or befouling indoor air, which is more pronounced than outdoor air causing approximately 3.8 million deaths. These alarming numbers highlighted the need to ameliorate indoor air quality and alleviate the risk of airborne infections.

Dr. Dhau engaged the participants with his next question, i.e., what is in the indoor air? Broaching about different pollutants as particles (dust, dust mites, and black carbon), gases (organic and inorganic), and bioaerosol particles [allergens and PBAP (primary biological aerosol particles)], he emphasized that the microbes, when prevalent in the air can penetrate in our body moving to the lungs thereby causing severe lung infections. In addition, these microbes can release some harmful chemicals called volatoxins or biogenic toxins in the indoor environment that have detrimental health effects.

Further, he explained the indoor airborne microbial exposure, which was one of the most cardinal parts of the webinar that highlighted risk associated with ICU visits by patients’ friends and relatives ICUs. According to the data collected, there were a 2-6x increase in pathogenic microbes during the ICU visit, thereby augmenting the problem rather than assuaging it. It has been observed that not only the number of microbes, but the diversity of microbes also increases during visitations. All these visitations put patients, especially immune-compromised patients under tremendous risk. Thus, Dr. Dhau accentuated that hospital-acquired infection is such a big issue. To mollify this, he jumped on to the goal of this webinar, “what makes the contaminated indoor air cleaner?”

For answering this very question, he acknowledged two chief points:
  1. First, the usage of HVAC systems fitted with mechanical filtration assembly can only control particle pollution, not gaseous pollution and probably is inadequate in preventing hospital-acquired infection.
  2. Second, is the use of portable air purifiers, which will not only capture but also destroy the microbial load in the air, which adds an extra layer of protection by ensuring that what is trapped on the filter are destroyed.

Finally, while confabulating the technical aspects of the Molekule Air Purifier, Dr. Dhau divided Purifier into two parts:

  1. Device part
  2. Filter part

He emphasized that Molekule air purification system is based on four pillars of quality to ensure clean air to everyone everywhere:

  1. 360˚ air intake
  2. 360˚ clean air outlet
  3. Particle capture
  4. PECO process.

While the first two are related to device the other two concerns filtration system. The unique Molekule filtration system has a filter loaded with catalyst particles that interact with UV-A light to degrade pollutants. The phenomenon is called Photoelectrochemical Oxidation (PECO) that is different from Photochemical oxidation (PCO) process.

Then in an expounding manner with the pictorial representation, Dr. Dhau explained the meaning of the destruction of the mold spores. Compared with the conventional filters, he talked about the superiority of PECO technology. Under a conducive environment, the trapped microbes on conventional mechanical filters may flourish and release harmful chemicals called endotoxin. On the other hand, the PECO filtration system ensures that the trapped microbes are destroyed completely, leaving no chance of their release back or their metabolic products to be introduced into the environment.

Unremittingly, Dr. Dhau talked about the third-party testing in which the chamber mimicked the real-world scenario. The testing evaluation of Molekule Air Pro purifier against mold spores and MS2 bacteriophages was presented. It was reported that 99.9999% (a six-log reduction) of mold spores and 99.999% (a five-log reduction) of viruses were removed in one hour and two hours, respectively. Surgical room infections are a big concern in the health sector. Molekule have launched another product, Rx Pro that has been specially designed for hospital applications and other large space applications such as kitchen, restaurants, and cannabis processing facility. A challenging study was undertaken to determine presence of infectious particles and evaluate the efficacy of Rx Pro in reducing the concentration in these particles in a real-world hospital environment. The study demonstrated that the use of HVAC system is not fully adequate in addressing airborne microbial exposure. On the other hand, the use of Rx Pro in a surgical room reduces the residence time of infectious particles in the air which in turn may reduce the extent of microbial exposure. 

Then, Dr. Jaspreet Dhau relinquished the next portion to Dr. Siddappa Byrareddy, who had researched SARS-CoV-2 in air, comparing aerosol risk indoors and outdoors. He then shared the experimental design in which the destruction of SARS-CoV-2 on PECO media was determined. He evoked that a filter swatch coated with PECO material abated the virus to a colossal extent. In a test involving the use of a multi-pass chamber, it was demonstrated that the airborne SARS-CoV-2 virus particles were removed with an efficiency of 99.98%. 

After the conclusion of the lecture, there was an interactive session between Dr. Jaspreet Dhau and the panelists, which included intellectuals, doctors, and professors.

Questions asked by various doctors, professors, and delegates.

Q. Is the air purifier available for domestic purposes? If yes, what is the cost and area covered by the purifier? (by Dr. Rajeev Kumar)

A. Yes, it is available for domestic purposes; one is Air Mini, and the other is Air Mini+ both cater to an area of about 250 sq. ft. Both the devices have a highest speed of 90 CFM. The difference between the two devices is that air mini plus comes with a particle sensor that provides information on the particulate matter concentration in air. The unit can be run on an Auto-protect mode that controls the functioning of the unit depending upon the indoor air quality. If the device senses that the air quality is not good, it augments the speed of the device and removes pollutants quickly from the air, and when air quality improves, it reverts to the normal speed.
COST= Rs. 37999 (AIR MINI), 
COST= Rs. 46999 (AIR MINI PLUS) 
Note: Molekule has reduced the prices on these units. They are being sold at under Rs. 30,000

Q. Which air purifier has air sensors in it? (by Dr. Sanjeev Gautam)

A. Air mini plus.

Q. Which is the best place to keep this purifier in the room? (by Mr. Abhinav Kapur)

A. They can be placed anywhere in a room, however for obtaining optimum benefits, it should be placed near the source of pollutants, or the breathing zone of a person. For example, near the bed of a sleeping person, on a Table while working at home or in office, near a patient’s bed in hospitals. Contaminated aerosols are continuously being generated while we speak, breathe, sneeze or cough. In hospitals and dental clinics, there are many aerosol generating procedures that may put contaminated particles in the air. Thus, keeping an air purifier near you sucks all airborne particles and purifies the air for healthy breathing. Keeping it very close to the door in the operation room helps the most as it decreases the particle residence time in the air and negates the impact of staff/nurses/doctors walking in and out of the operating room. While sleeping, keeping it at 3 to 4 feet away from your head will be the best place to get optimum benefit of clean air.

Q. What is the lifetime of the filter, and whether they are replaceable? (by Dr. Aman Bhalla)

A. The filter’s life is six months, and yes, they can be replaced.

Q. What are the specific recommendations regarding the capacity or number of air purifiers, and what volume can be purified with the time factor involved? (by Miss Ishanpreet Kaur)

A. Air mini serves around 250 sq. ft. of an area and circulates 90 cubic feet of air per minute. For example, if your room is 900 sq. ft. in area, it will take 10 minutes to pass all the air through it or in other words you will have six air changes per hour.

Q. Since air purifiers use free radicals to kill pollutants, have you measured the amount of ozone produced by the purifier? (by Mr. Vishal Verma)

A. The light used in Molekule air purifiers is UV-A and not UV-C having wavelength quite close to the visible region. This is low energy radiation, and therefore, ozone is not generated at all. Testing was done not only internally but also at third-party labs, including testing at Lawrence Berkeley National Lab, where we have demonstrated that Molekule air purifier doesn’t produce ozone. In fact, it has been demonstrated that these devices help in reducing the ozone level in the air.

Q. Have you conducted a study to compare the efficacy of your purifier with the traditional purifier without PECO technology to reduce transmission of virus indoors? (by Mr. Vishal Verma)

A. We reduce the viral load and diminish the exposure of pathogens, but transmission is something on the health side. We are doing clinical trials, but we aren’t saying anything about the transmission. And yes, we have compared our filter with the traditional filter; traditional filters just capture microbes, and the microbes live on these filters either in a dormant state or could live under conducive environment, but PECO filters wrecked all those microbes (converting organic molecules into carbon dioxide and water), so therefore, no chance of survival and release of their metabolic products.

Q. Does the efficiency of the filter depend upon the humidity level in the air? (by Aman Chauhan)

A. It does; almost all types of air filtration systems are affected by environmental factors.Mechanical filtration efficiency with electrostatic media changes with the level of moisture in the air. Carbon filter absorption capacity and efficiency change with a change in RH. Photochemical and photoelectrochemical oxidation efficiency changes with the change in RH. We have observed that an optimum level of VOC degradation efficiency is achieved when and there are instances if the humidity level is between 40-60%. 

Q. How are you ensuring adequate mass transfer of the pollutants on the catalyst as there are other competing entities? (by Aman Chauhan)

A. The amount of catalyst we put on the filtration media ensures that an optimum number of pollutant-catalyst collisions does happen. There’s a role of humidity since now water can also compete, but overall, the design of our filter is such that the impact is minimal. 

Q. How are trapped organisms treated? (by Dr. Jyoti Sharma)

A. Everything is happening simultaneously; first, the particles, including viable and non-viable microbes, are captured on the filtration media, and as the light is continuously shining on the filter, the catalyst gets activated and generates holes and electrons, which interacts with water molecules generating hydroxyl radicals which then reacts with any complex molecules or VOCs and break carbon-carbon or carbon-nitrogen bonds into carbon dioxide and water. Under no circumstances these hydroxyl radicals are released into the air; they remain attached to the catalyst’s surface (in short, it is a heterogeneous catalytic reaction aided by the light that degrades organisms). 

Q. For how long do we need to keep our purifier switched on, and how we’ll know that room air is purified? (by Dr. Varinder Garg)

A. Pollutants are released in the indoor environment when we run any electronic devices in our homes, cook food in the kitchen, or install new furniture. In India, where houses are not closed, we keep our windows open with screen doors; the outside air quality also impacts indoor air quality. So, indoor air quality changes every moment and needs to be monitored. The sensor inside the Air Mini+ device monitors air quality, and if the unit is running at Auto-protect mode, it will run at different speeds to address changes in air quality. 

Q. Does the speed of the blower affect the efficacy of the purifier? (by Dr. Ramesh Sharma)

A. CADR (clean air delivery rate) combines airflow and filtration efficiency; the higher the flow, the higher the volume of air passing through it, cleaning happens at a quicker rate. The mechanical filtration efficiency doesn’t change majorly with speed.

Q. When we move outdoors from a room with an air purifier, do we face any issues like acclimatization? (by Miss Anjali Hunger)

A. No, the air quality indoors is bad compared to outside, so having a good quality of air inside where we spend 80% of the time helps us cope with the pollution outside.

Q. Have you carried out any studies or data comparing HEPA filters and PECO technology? (by Dr. B S Sooch)

A. Yes, HEPA filters trap particles only, but PECO filters capture and kills/destroy organic pollutants including microbes and allergens. In addition, PECO filtration system degrades VOCs, whereas HEPA filters are not meant to capture or destroy VOCs.

Q. Can I open my windows where an air purifier is running? (by Miss Ishneet Kaur)

A. When the quality outside is bad (some forest fires, smog, etc.), it is recommended to close the windows, but you can open the window if the air quality outside is good.

Q. How is this air purifier different from laminar airflow technology used in modular operation theatres and neutropenia wards, and whether you have done cost-effectiveness studies? (by Dr. Manjeet)

A. Laminar airflow comes from HVAC systems fitted with an array of filters (prefilter and final filter). Prefilter is of lower efficiency and captures big particles, and final filters have higher efficiency between MERV 13 to MERV 17, which loosely are called HEPA filters, which captures tiny particles. Remember, filters with a MERV rating of 17 and above are true HEPA; all others are not. According to US-EPA, HEPA air filter can theoretically remove at least 99.97% of any airborne particles with a size of 0.3 microns (µm) and above. Treated air from the HVAC system is a mixture of filtered air and outside air. Thus, the HVAC system dilutes the indoor air and help in the reducing the microbial load in the air in general. On the other hand, a portable air purifier is a targeted intervention that enhances air quality by removing/eliminating airborne microbes from the vicinity of a patient, doctors, and staff. HVAC is quite costly and require regular maintenance, but on the other side, portable air purifiers are cheaper and easy to maintain and replace. 

This was all for one of the most captivating webinars that I have attended as of now, and I must mention that Dr. Jaspreet Dhau was so eloquent and self-assertive that he kept me curious during the whole of the lecture.


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Jaspreet Dhau

Great article, Ishneet! You have put your perspective beautifully by highlighting concerns about indoor air quality and the potential impacts and remediation of airborne viral exposure. I couldn’t have done better, Congratulations!

Ishneet kaur

Thank you so much, sir.