Air Purifiers explained

Ionizers, PCO's, UV and Just Plain Ol' Regular Filters

I am a proponent of sticking with standard mechanical particulate filtration, for example, the common 1-, 2- or 4-inch thick pleated “paper” inserts; and in the case of special applications, the commonly called “HEPA” filter.

This is standard recommendation because it works and is affordably maintained.

I.          Mechanical Filtration

The simple description of a mechanical particulate filter is a non-reactive inert material that captures airborne solid particulates and keeps them from becoming re-aerosolized.

The efficiency of this type of filter is measured both by the size of particulates captured and capture efficiency (the percentage of total particles captured). For commercial and residential applications, these filters are rated using a system and label called MERV.

A.    MERV Rating

The higher the rating number, the better the filter. With each increase in rating, smaller particulates are captured and more of each size category is captured.  MERV 8 - 11 is typical for commercial systems.

MERV 8 is 90% efficient at 3 microns (which is “huge” - it is 10x larger than the tiny particles that HEPA collects!). This means it does not capture the fine particles known as PM2.5.

MERV 11 is 95% 1 to 3 microns; which means it does a good job capturing the PM2.5 particulates.

B.     HEPA

HEPA is the highest grade of mechanical particulate filter. HEPA is generally used for high-risk applications like hospital surgeries or pharmaceutical manufacturing clean rooms. HEPA collects particles of 0.3 micron at 99.97% efficiency. This means only 3 of 1000 particles 0.3 microns in size can get past the filter. The HEPA is rated at MERV 17.

Importantly - The diameter specification of 0.3 microns responds to the worst case; it is called the “most penetrating particle size” (MPPS). Particles that are larger (e.g., 1 micron) or smaller (e.g., 1/10 of a micron, aka Ultra-Fine particles) are actually trapped with higher than 99.97% efficiency. This is a good thing!

To Learn MORE ABOUT HEPA filters, please see this short blog I prepared to answer some of confusion out there when marketing gets in the way of the science and facts!

PM 2.5

Especially important consideration for indoor air quality is the fine particulate fraction called PM2.5. These are particles 2.5 microns in diameter. Reducing the concentration is important for health. For decades it has been widely accepted that high concentrations of PM2.5 air pollution are correlated to health problems, both indoors and out.

From the facility indoor air quality point of view, any filter or purifier that can reduce PM2.5 is going to provide some advantage and benefit.

Mycotoxins and HEPA Filters

To Learn MORE ABOUT MYCOTOXINS and why HEPA filters WILL remove them from the air and cleaning WILL remove them from the surfaces in your home, please see this short blog I prepared to answer some of confusion out there when marketing gets in the way of the facts and science …

II.        Purifiers

There are also non-mechanical air cleaning devices, usually labelled “purifiers” instead of “filters”.

In California, which regulates output of air cleaning devices for such contaminants as Ozone, these are call “electronic air cleaners”. The “electronic air cleaner" category includes ionizers, electrostatic precipitators, PCOs, hydroxyl generators, devices with UV light components, and other electronic air cleaning technologies.

The electronic air cleaners intentionally produce and emit chemical compounds or molecules claimed to remove other compounds (i.e., via chemical reaction). Purifiers produce chemicals such as hydroxyls, UltraViolet light, Ozone, molecular peroxides, and Ions. The Pinpoint Bipolar Ionizer (PPBI or BPI) is one of these.

These purifiers are best left to special high risk situations, situations where the results are measurable (or predictable based on prior relevant studies or demonstrations), or where the Precautionary Principle is warranted (“just in case” and probably not provable). Germicidal Ultraviolet might have one design that is useful in a few special commercial applications.

A.    Bipolar Ionizers

With regard to how Bipolar Ionizers work: the science is actually simple and straightforward. The machine creates ions, which create charged particles, which then are attracted to each others. The small particles agglomerate (stick) with other small ones and then either get heavy and fall out of the air (making surfaces more dusty than previous) or they remain airborne but are large enough to get captured by a low MERV filter that they otherwise were too small to get captured before ionization - for example, a MERV 8 usually captures 3 micron, and the ionizer is claimed to combine multiple 1 micron particles to create larger size particles.

One claim (unproven, no papers or studies available) about ionizer effectiveness is that using an ionizer is the equivalent of moving up 3 MERV ratings. So if you currently have MERV 8 filters, and you add an Ionizer, the end result is supposed to be like having MERV 11 in your air handler system. A cost-benefit can be easily calculated using this “rule of thumb”. (I have not seen the reference for this, but it’s simple and I I like using it for planning and decision-making discussions.)

However, these claims become suspect in the applied situation, like in a large or complex commercial building, or in buildings with no heavy particulate pollution load to begin with.

The more complex and the larger the space, the more inputs (exit doors, occupants, pollution sources) the less likely you will see a difference from an ionizer located in the air handler.

The claims are also suspect with regard to actual disinfection of microbial pathogens such as bacteria, mold spores, or virus.

Many bipolar ionizers are made by GPS (Global Plasma Solutions).

The other large manufacturer is RGF, who makes the Reme Halo.

Other BPI brands include Nu-Calgon i-Wave (by GPS). Air Knight IPG. Air Oasis Bi-Polar. and APCO Air Scrubber.

B.     Bipolar Risk

The most important thing everyone should know when considering any “air purifier” purchase these days is this:

Several months ago, May 2021, a Personal Injury Product Liability lawsuit against GPS was filed for false and misleading advertising of the Bipolar Ionizers (aka BPI).

III.      Supporting Sources and References

Here are quotes from some highly respected sources provide similar comment and critique on the bipolar ionization purification technology:

From Bill Bahnfleth, PhD, a Penn State researcher, (from personal conversation)

“The problem with most of the testing these manufacturers point to is that it does not reflect application conditions. Ionizers in tiny chambers positioned directly over a surface sample. There is a lot of interesting information in the Trane report (see pdf). They used MS2 phage; 1000 ft^3 chamber. Results: had No effect on surface contamination; had little or no effect on chemicals; and very mixed results for air disinfection. “

From Scott Armour regarding the Trane research:

"Some of the larger particles increased in concentration after ionization! some of the smaller particles decreased in concentration. There is no further explanation or research to understand this phenomenon. The valid conclusion is that there is no definitive way to predict improvement in the occupied space.).

pdf is online,"

https://www.jp.

trane.com/content/dam/Trane/Commercial/global/about-us/wellsphere/Technology%20Whitepaper%20-%20Bipolar%20Ionization.pdf

From an EPA webpage on Indoor Air Quality,

“Ion generators act by charging the particles in a room so that they are attracted to walls, floors, tabletops, draperies, occupants, etc. Abrasion can result in these particles being resuspended into the air. In some cases these devices contain a collector to attract the charged particles back to the unit. While ion generators may remove small particles (e.g., those in tobacco smoke) from the indoor air, they do not remove gases or odors, and may be relatively ineffective in removing large particles such as pollen and house dust allergens. Although some have suggested that these devices provide a benefit by rectifying a hypothesized ion imbalance, no controlled studies have confirmed this effect.”

https://www.epa.gov/indoor-air-quality-iaq/what-are-ionizers-and-other-ozone-generating-air-cleaners

Bud Offerman, CIH, PE, a highly respected colleague, industry expert, Stanford trained IAQ Expert

"Nor should we expect these ionization devices to have a significant effect on airborne concentrations. While ionization of air can increase the deposition rates of particulates onto indoor surfaces, this effect is small compared to the overall removal by ventilation and filtration, and hence ionization does not significantly reduce indoor concentrations."

Link to his Nov 2020 article;

http://www.iee-sf.com/TheCOVID19SnakeOilSalesmenAreHere.pdf.pdf

Recent Bi-Polar Ionizer ENEWvents

May 7, 2021:  Garner v Global Plasma Solutions, USD Delaware, 2021

https://dockets.justia.com/docket/delaware/dedce/1:2021cv00665/75416

California Air Resources Board,

How to Select a Safe and Effective Air Cleaner, 2021 update

https://ww2.arb.ca.gov/list-carb-certified-air-cleaning-devices

First-Steps Toward Achieving Healthful Indoor Air Quality,  Nov 2020 update

https://ww2.arb.ca.gov/resources/fact-sheets/air-cleaning-devices-home

Most of this discussion will apply to the standard forced air commercial and small residential HVAC and air handler systems.

Your HVAC contractor can provide additional technical details of your existing system if required.

I will be happy to review and approve those as necessary!