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Air purifiers from HEPA to Photocatalytic oxidation (PCO) have become essential in homes and for military

To stay healthy, we need to pay not only close attention to what is in the food we eat and the water we drink but also the quality of the air we breathe. The air we breathe both indoors and out can directly impact our health, quality of life, and state of mind. In today’s increasingly congested communities, the quality of our air is becoming a rising concern. What’s more, is that the quality of the air INSIDE your home or office is often worse than the air outside. Poor indoor air quality can lead to an increased occurrence of respiratory problems like allergies, asthma, or COPD.

 

Many triggers can be lurking in the home; the bathroom can harbor mold and mildew; the living room can have animal hair, dust, dander, or smoke; and your bedroom could be contaminated with VOCs (Volatile Organic Compounds) from furniture, household cleaners, paint, carpet, air fresheners, and perfumes.

 

The virus that causes Covid-19 is mainly spread through respiratory droplets that are expelled when an infected person talks, coughs, sneezes or breathes, and are inhaled by another person. But the virus can also be spread through smaller airborne particles that have been “aerosolized” and linger in the air for minutes or hours.

 

Using a portable air purifier can reduce the airborne viruses and germs in your home and other indoor spaces. While furnace filters and HVAC systems have built-in filters, these portable devices add a layer of air cleaning to individual rooms. Air purifiers filter out airborne contaminants and clean the air in an indoor space, These devices typically consist of a filter and a fan: The air purifier pulls air in, passes it through a filter that removes small airborne particles and then dumps clean air back in the room.

 

According to the Centers for Disease Control, poorly ventilated spaces increase the risk of Covid-19 transmission, because the virus can linger in the air and be inhaled by others. Air purifiers can be a helpful tool to use in homes and confined indoor spaces because they increase air circulation, which introduces fresh air into a space while removing potentially contaminated air.

 

But portable air purifiers alone can’t prevent Covid-19 transmission. Air purifiers with HEPA, or “high-efficiency particulate air” filters are the best option for consumers because they can capture at least 99.97% of airborne particles that are at least 0.3 microns in size, Shelly Miller, professor of mechanical engineering at the University of Colorado Boulder who studies urban air pollution,  says. However the Covid-19 virus is about 125 nanometers or 0.125 microns large, so it is technically smaller than what consumer purifiers would capture. But experts say that when the virus is encapsulated in a respiratory droplet, a HEPA filter may be able to trap and remove the particles. Air purifiers, however, do not replace the need to wear a face mask, maintain social distance and practice hand hygiene.

 

Military requirements

The Military also requires Air filtration to ensure the safety of their soldiers and their equipment. Whether it be in environments where items are being manufactured or within the barracks, you want to be sure that everything and everyone is functioning at 100 percent always.  Each specific military process needs its own air filtration system to ensure the safety of equipment and workers. Some of the typical air quality challenges the military faces are:

Dust Collection: One of the most dangerous chemicals that can be produced in military production is chromium dust and residue that can result from sanding jets or as a byproduct of the welding process. It is important to use bag or cartridge filters to collect this dust and dispose of it properly.

HEPA Filters: These high-efficiency filters can be placed directly within the air conditioning system and work passively to filter the air throughout the day. This can help keep a workroom clear of debris and dust that will harm equipment.

Aluminum Mesh: Like HEPA filters, these are efficient but with the bonus of being washable. Because they do not work as well as HEPA filters, they are best used in common areas such as hallways or barracks.

The best way to go about picking which filtration system should go where is by determining the applications involved in the space that needs to be filtered. For example, warehouses and storage areas that need to be clear of any dust or moisture should use a HEPA or aluminum mesh system. Meanwhile, production areas would benefit from dust collection units.

 

Photocatalytic oxidation (PCO)

Photocatalytic oxidation (PCO), as the name suggests, employs ultraviolet light photons and a catalyst: a proprietary mixture of various catalytic particles adhered to a target surface. As photons from the UV light shine on the catalyst, a reaction occurs creating ions that decontaminate air and surfaces. These ions are created when H20 vapor is rearranged by the catalytic reaction into other ions. PCO will take harmful contaminants, such as viruses, bacteria, VOC’s and of course, the SARS-CoV-2 virus and destroys the organic compounds by turning them into CO2 and water.

 

Simply speaking, a catalyst is a substance that makes a chemical reaction more likely to happen by reducing the energy needed to kick start it (“activation energy,” as it’s known). In photocatalytic air purifiers, the catalyst that cleans the air is typically titanium dioxide (sometimes called titania) and it’s energized by ultraviolet (UV) light. UV is the short-wavelength light just beyond the blue/violet part of the electromagnetic spectrum that our eyes can detect. When UV light ( shines on the titanium dioxide, electrons (the tiny, negatively charged particles inside atoms) are released at its surface. The electrons interact with water molecules (H2O) in the air, breaking them up into hydroxyl radicals (OH·), which are highly reactive, short-lived, uncharged forms of hydroxide ions (OH−). These small, agile hydroxyl radicals then attack bigger organic (carbon-based) pollutant molecules, breaking apart their chemical bonds and turning them into harmless substances such as carbon dioxide and water.

 

Here, then, is the big advantage that photocatalytic air purifiers have over other air-cleaning technologies, such as filters: instead of simply trapping pollutants (which still have to be disposed of somehow), they completely transform the harmful chemicals and effectively destroy them.

 

Drawbacks

The disadvantage of this process is that photocatalytic purifiers can also produce tiny amounts of ozone (O3), a chemical variant of the oxygen in the air that is, in itself, a toxic air pollutant.  Purifier makers claim the amounts of ozone produced are well within the guideline limit (0.05 parts per million) suggested by the US FDA but, even so, this is something to bear in mind.

 

Although hydroxyl radicals occur naturally in the atmosphere, they can themselves pose dangers. If your indoor air contains volatile organic compounds (VOCs—the easily evaporating chemicals used in things like paints and hairsprays), instead of removing them completely, a photocatalytic air purifier may chemically convert them into other unpleasant pollutants, including formaldehyde and acetaldehyde.  All told, there is some debate and uncertainty over whether the pollutants produced by photocatalytic air purifiers could pose a greater risk to human health than the ones they are designed to remove.

 

Basic PCO isn’t very effective; it only creates short-lived hydroxyl ions that don’t last long enough to decontaminate your living space.

 

Air-Clenz Systems Announces Technology Breakthrough That Captures, Isolates, and Cleans Exhaled Air in 10 Seconds and Within Two Feet of Individuals, reported in July 2021

Many viruses — including COVID-19 — are primarily spread in aerosol form through the air and are generally not captured quickly by current HVAC systems. These ventilation systems pull pathogens across a room — and past other individuals — to a distant air return point, which increases the risk of disease transmission even in systems with advanced filtration and other treatment methods.

 

Research reports published earlier this year in the British Medical Journal and Lancet state that COVID-19 and its variants are spread mainly through inhaling fine aerosol particles that stay in the air for hours. Earlier this year, the Centers for Disease Control, and the World Health Organization both acknowledged aerosols as the primary cause of the spread of COVID-19. Several studies show that contagious pathogens such as COVID-19, the influenza virus, and even the common cold can travel through the air in aerosol format for more than 15 minutes and over tens of feet before being captured by traditional HVAC air intakes.

 

The Air-Clenz technology works faster and more effectively than ventilation systems (such as HVAC systems and air purifiers) because Air-Clenz’ proprietary exhaled air collector is positioned in or on the back of a seat, typically within two feet of a seated individual’s face. HVAC systems are not designed to quickly capture exhaled air, and air purifiers are designed to generally clean air within a small or medium sized room. Thus, the concentration of captured room air is greater than that of any captured exhaled air. However, Air-Clenz was designed to capture, isolate, and clean a significant amount of each exhaled air breath before it has a chance to disperse throughout the venue.

 

Each Air-Clenz exhaled air collector captures and isolates most of a seated individual’s exhaled breath. The captured air is then cleaned within an air purification chamber and the cleansed air is either released back into the indoor venue or is moved into the venue’s HVAC system for return into the venue.

 

“The Air-Clenz technology is designed for airplanes, mass transit, vehicles, theaters and other multi-seat environments,” said Stuart Sheldon, CEO and President of Air-Clenz. “Our proprietary exhaled air purification technology captures, isolates, and removes pathogens quicker than ever before. The Air-Clenz technology is the result of a collaborative design effort that includes a scientific advisory board of seven distinguished scientists, healthcare professionals, and mechanical engineers.”

 

The need to improve indoor air quality has taken on new importance since the coronavirus pandemic. A distinguished group of 39 scientists led by Lidia Morawska, aerosol physicist at Queensland University of Technology in Australia, called for indoor air regulations in a paper published last month in the journal Science. A recent University of New Mexico study of air quality in airplane cabins, published in the journal Physics of Fluids, indicated that while aircraft companies promote the complete renewal of the air in the aircraft cabin every 2-3 minutes, sophisticated modeling shows that aircraft ventilation systems remove only approximately 25 percent of pathogens from the air in the cabin. Contaminants were found on passenger clothing, seats, and on the walls and floor of the cabin.

 

Initial research of Air-Clenz’ technology in seated, indoor environments indicates that its system typically captures an estimated 80-plus percent of a person’s exhaled breath within 10 seconds. “Removing viruses quickly and close to the mouths and noses of seated individuals in such environments will most definitely reduce the spread of current viruses such as the Delta variant, as well as future viruses, such as the common cold, influenza, and the next COVID-like virus,” explained Sheldon. “It makes economic sense, too. Numerous authorities estimate the global economic cost of COVID-19 at more than $20 trillion, and yearly losses from the flu and other respiratory viruses cost billions and billions of dollars. Air-Clenz’ technology is a cost-effective solution to this challenge.”

 

Research has shown that when air quality is improved, the overall quality of life increases through higher productivity, fewer sick days, and sharper focus. Protect the air we breathe inside our home, workspaces, and other, more public locations to minimize the risk of potential widespread illnesses.

 

References and Resources also include:

https://www.explainthatstuff.com/how-photocatalytic-air-purifiers-work.html

https://www.businesswire.com/news/home/20210719005108/en/Air-Clenz-Systems-Announces-Technology-Breakthrough-That-Captures-Isolates-and-Cleans-Exhaled-Air-in-10-Seconds-and-Within-Two-Feet-of-Individuals

 

About Rajesh Uppal

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