Active VS Passive AIR PURIFYING

There are many different types of air purifiers on the market today. They range from small to large and cheap to very expensive. What most people don't really realize is that there is a wide difference in technology, which will have a major difference on performance. The intent of this paper is to explore these differences and explain why specifically designed bi-polar ionization technology should be considered as part of your overall solution. 

PASSIVE AIR PURIFYING

The most common type of air purification is through filtration. If you have a home furnace, the filter on your furnace is acting as a passive air purifying system. It is called passive because it can only purify air that it can pull through its filter and it is limited to how much it can do because of the filter and the fan in the unit that pulls the air through it. Many models will state how many square feet of air that a unit can filter on the specifications. Because of the limitations of what a filter can handle, it may take more than one unit to do an area or one unit per room in a home or office.

Examples of passive air purification include MERV 13 filters, HEPA filters, UV technology (installed near or around the filters near your air handling units for facilities or homes that have central HVAC systems) and standalone units used to filter the air in a room.

Standalone air filtration units need to be used in the correct application or they can present other unintended problems. For example, if a standalone unit is plugged into the back of a classroom, and a student sneezes or coughs or has a virus and exhales, the air filtration unit is naturally pulling air to the back of the classroom in order to get it filtered. The air that is carrying a virus that was exhaled by the student in the front of the classroom is now being pulled through the rest of the students on its journey to the standalone unit. This passive system has therefore created potential risk for the majority of the students in the classroom.  In general, standalone units are better suited for homes, patient rooms or apartments with low occupant density, but caution needs to be taken for the same reason. Also, trip hazards are a concern, along with ongoing maintenance of the filters. Consult your manufacture recommendations to ensure that maintenance considerations are well understood before investing in this technology. 

ACTIVE AIR PURIFYING

Active air purifiers are used on the supply side of a building. Because of the lack of awareness of active air purifying technologies, many facilities have opted to increase their ventilation in their buildings in an effort to “dilute” the density of the virus. During cold winter months, this can be a challenge, since the indoor temperature will drop and energy bills will rise with significant opening of windows. Though ventilation is very important, a more sustainable and energy-efficient solution is using an active air purifying technology that scrubs the air clean of harmful VOCs, bacteria and viruses. The main functional difference between active air purifying technologies and passive systems is that active systems do not rely on the air to make their way through a filter; rather, these technologies produce healthy ions that naturally seek and inactivate harmful contaminants. 

Before we get to a few popular technologies in this field, it’s important to understand the physics behind the technology. Ions are produced naturally in the bottom layer of the Earth’s atmosphere, the troposhere. When you are up on a mountain top or near waterfalls, nature produces very high ion concentration levels. After a heavy rain or thunder storm, there is a desirable “clean”  odor outdoors – those are ions you are breathing because rainstorms create them. These ions are actively and naturally scrubbing the air you breathe. The problem is when you get to more denser populated towns and cities, typical ion levels drop dramatically. In these same dense towns and cities – the indoor air has even fewer ions. Fewer ions in the air allow VOCs, bacteria and viruses to float freely, infecting and harming people.

So how does it exactly work? 

Brittanica’s definition of an Ion: Any atom or group of atoms that bears one or more positive or negative electrical charges. 

What we are interested in though, is not any ion. We are interested in the hydroxyl radical (OH), which is formed by an excited oxygen ion reacting with water vapor.

Why? Because the (OH) is missing a hydrogen atom, or (H), to make it (H2O).

Why is that important? Because the (OH), or hydroxyl radical, in physics will always seek to find another hydrogen atom – and VOCs, bacteria and viruses all have an (H) to give. When it finds its victim, it will inactivate it by pulling an (H) from it. It’s that simple and extremely exciting because physics does not know Sars-Cov-2 from any other virus and it will never know if the virus mutates or if another virus appears because it will always look for that hydrogen atom to complete itself and inactivate the harmful VOC, bacteria or virus, whether it is Sars-Cov-2 or Sars-Cov-22. 

Now that we have your attention, lets discuss how we can produce millions of ions indoors to inactivate and scrub the air as people are breathing.

One emerging technology is photocatalytic oxidation (PCO). There are companies that have equipment that produce these hydroxyl radicals (OH). The Earth’s atosphere actively produces billions of (OH) constantly. Why is this important to note? Because these (OH) last less than a second. That works in the Earth’s atmosphere but it is not so effective when manmade technology produces them. It tends to act more like a passive system in duct work much like UV sterilization, cleaning the air that is passing through the system.

The more advanced technology producing OH uses bi-polar ionization (BPI) producing technology that produces ions that last much longer.

The two most common forms of this kind of technology are both patented technologies. It is important to understand the difference between the two because, though they are both in the family of bi-polar ionization, there are very clear differences.

Dielectric Barrier Discharge Bi-Polar Ionization (DBD BPI) VS. NeedlePoint BPI (NBPI)

Dielectric Barrier Discharge Bi-Polar Ionization (DBD BPI)

DBD BPI is manufactured in the USA by Clean Air Group LLC based in Fairfield CT under the AtmosAir brand, and distributed by Pandemic Solutions Inc, headquartered out of New Rochelle NY, the site of the first USA epicenter.

DBD BPI uses a patented technology that replicates natural cleaning compounds created by nature, similar to the heavy rainfall we described earlier. The technology uses BPI or bi-polar ionization (negatively and positively charged ions) and active oxygen produced by units installed in the supply ductwork of an HVAC system. The healthy ions go out from the supply vent to clean the air (remember Passive Air Purifying systems use the “return ducts” to do their work pulling air in), thus allowing it to affect a larger area than a passive system. There are few if any limitations on how much square footage it can cover, but it is much higher than any passive system that has to filter the air.

BPI deals with a number of sources that cause odors such as bacteria, VOCs and mold. So, in addition to removing particles from the air, the active oxygen removes odors that will make the indoor space smell fresh and clean.

DBD Bi-Polar Ionization, relates to the physical construction of the ionizing tube (electrode). 

·       One model, for example, with an F sized tube uses a 21-inch tube (electrode) to treat approximately 2,500 square feet or 2,500 CFM. 

·       Further evidence of the large volume of space that DBD BPI technology can purify includes an example of one of its larger units. The 508FC model has (8) 21” tubes per system. Each tube can discharge 75,000 ions per second covering 15,000 square feet or 15,000 CFM.

·       A most critical difference with AtmosAir’s technology is that the electrode is inside of the ionizing tube. AtmosAir’s unexposed design prevents oxidation from occurring as quickly as an exposed design. 

·       This DBD BPI is designed to be UL2998 Compliant or Verified Zero Ozone Technology. 

·       This engineered ionizing tube meets the requirements for ASHREA’s 62.1 Indoor Air Quality Procedure, so it will allow a facility to decrease the amount of outdoor air brought into its building which will reduce energy consumption and expense.

·       The design of these ionizing tubes prevents the electrode/ cathode from acting as an electrostatic precipitator giving it a longer lifespan than a needlepoint design. 

·       The composite tube acts as a “barrier” between the inner core (electrode) where input voltage is applied. The voltage tries to “jump” to the outside of the tube but cannot because of the Dielectric Barrier. This process creates a rapidly alternating energy field that converts oxygen molecules into positively or negatively charged oxygen ions that last 300 seconds or more.

Needlepoint Ionization 

Needlepoint technology (NBPI) is patented and is produced by Needlepoint Global Plasma Solutions located in Charlotte, NC. The product is manufactured in China. It private labels its product to other companies (IE iWave). Needlepoint or brush ionization uses DC or AC voltage applied to a set of quarter-inch Needlepoints or brushes (electrodes). Here are some key facts with 

§  Most needlepoint designs use a quarter inch (0.25”) electrode (needlepoint). 

§  Needlepoint systems use exposed electrodes to generate air ionization. 

§  NP ionizers produce single polarity ions at separate needlepoints. Alternating current systems produce both polarities of air ions at each needlepoint. 

§  When a carbon brush is subjected to a ‘coldplasma discharge’ it eventually burns, as it is carbon after all. This turns to ash and ‘clogs’ the emitter reducing ion emission effectiveness severely. This is another reason why you may see products with ‘wiper arms’ which clean off the dead brush debris. The wiper arms rely on a stepper motor which will wear out over time. Any product that is not self-cleaning is sure to need to be replaced at some point. 

§  Most HVAC professionals has experienced seeing a dirty coil or dirty return filter. Most can envision the fact that a 0.25” needlepoint upstream of a coil stands little to no chance of not getting covered by particles just as a media filter would. They require constant cleaning for effectiveness. 

In conclusion, although passive air purifying technology is a great first step, very little compares to the AtmosAir bi-polar technology that exists today – by far the most advanced active air purifying system on the market that is proven to reduce the coronavirus by 99.92% in 30 minutes. Even more importantly, it is an investment in proactive technology that does not care which virus it is inactivating – it is a system that will work with any virus including the latest variants or any other harmful bacteria or viruses we encounter in the future. 

References: Special thank you to The Nature of Air 2019 by Terrapin Bright Green, AtmosAir Solutions, and our Advisory Board Member, Jeremy McDonald, a principle member of GuthDeConzo.

Author: Peter Cantone is CEO and Founder of Pandemic Solutions LLC. 

Date: April 10, 2021