Air Purifier Terms – Stripped & Simplified For Understanding

When it comes to Air Purifiers, it’s not just acronyms that can stump you; it’s the terminology as well.

In the list below, are the terms I’ve come across while researching.

Some are scientific. I’m not a scientist, so the explanations are more from a layman’s perspective. I’ve made sure the wording is in line with the science. But more understandable to the non-scientifically inclined.

The aim is to allow you to cut through the jargon and understand enough to make a knowledgeable decision.

Activated Carbon

You’ll come across the term activated carbon because it is a key air filter material. Key to removing odors and chemicals in the air.

It is often charcoal based but also comes from coal or coke. Application of heat or another treatment spawns millions of small pores in the carbon. The result is a vast increase in porous surface area.

Particles creating odors, or containing chemicals and gasses are too small for HEPA filters. But treated carbon attracts the chemicals in the particles. These attach to the carbon as the air passes through the carbon. Known as the process of adsorption (see following). It means cleaner air blows back into the room.

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Absorption v Adsorption

I was stumped when I saw the term adsorption. Just as you might be.

Absorption is a more familiar term. It’s the process that occurs when something is taken in wholly by another. For instance, water absorbed by a sponge disappears. It’s sucked up by the sponge and is no longer a separate independent element but a part of the sponge.

Absorption can also occur in the context of a chemical reaction. For example, sodium hydroxide exposed to air. It reacts with the carbon dioxide by absorbing it to create sodium carbonate. So the sodium hydroxide takes in all the carbon dioxide affected by the reaction. And produces a different substance altogether. Of course, carbon dioxide remains in the air. But less the amount that reacts with the sodium hydroxide.

Absorption results in an even distribution of the absorbed substance in the absorbing material. Both in the physical and chemical instance.

Adsorption is different altogether.

A substance remains whole but adheres or sticks to the surface of another. It’s a surface process involving the accumulation of a gas or liquid on a liquid or solid. It doesn’t include the trapping of solid matter.

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Air Filter

Have you seen the term “air filter” when researching Air Purifiers?

Probably not all that often. But don’t be confused. In most cases, it’ll mean the same thing.

“Air Filter” is more likely to be used when talking about the whole of house heating or cooling systems. In this case, the air filter is the device that protects the system from dirt, dust, and debris. It’s not about cleaning the air to protect your health.

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Airborne Particles

Wikipedia describes a particle “as a minute fragment or quantity of matter”.

Airborne particles are particles suspended or floating in the air. They can be solid or liquid but are tiny and microscopic. They are the main constituent of polluting haze, smoke, and airborne dust. Also referred to as particulate matter, this pollution contains a broad range of elements. Including acids, allergens, soil, metals, organic chemicals, etc. None of which are good to breathe.

Particulate matter can cause serious health issues. Being so small it enters your lungs. And sometimes your bloodstream to aggravate any unhealthy condition. Long term exposure is of particular concern. As is the impact on people with heart or lung disease, older adults, and younger children.

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An atom is the smallest unit of matter that can exist. And matter is anything physical, i.e., anything that can be touched. Except for energy everything in the universe is made of matter.

Three particles make up an atom: protons, neutrons, and electrons.

The nucleus is the center of an atom. It contains the two heavier particles, protons, and neutrons. The electrons are much lighter and orbit in a cloud around the nucleus.

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Electrostatic Precipitator

An electronic precipitator is a device. It attacks suspended fine particles present in flowing gasses or exhaust. Particles like dust or smoke. The precipitator directs a high-voltage electrostatic charge.

But only at the particulate matter in the flowing gas. It traps and collects the positively charged particles on negatively charged plates. Such focused application of energy doesn’t impede the flow of gas. And is super-efficient in its use of electricity.

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Energy Efficiency

Energy efficiency as a phrase means what it says. It’s all about the efficient use of energy. In simple terms, it’s describes reducing the energy used to provide the same service.

With air purifiers, this term is used to highlight if one purifier is better at cleaning the air. And doing so by using less electricity.

But it’s not just about a product or service that uses less power. For example, it can refer to improving the insulation in a house to seal in the air. So warm air doesn’t escape in winter and hot air enter in summer. Requiring less heating in winter and air-conditioning in summer. In turn leading to lower energy usage and costs.

Note that energy efficiency is not the same as energy conservation.

With energy efficiency, you continue to use products and services. At the same time, you’re trying to reduce the amount of energy required. Energy conservation is about not using goods and services. Or at least reducing their usage. So that in the extreme you’re not using any energy at all.

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You can get the chemical explanation at Wikipedia.. Be warned though it’s complicated.

Explaining hydroxyls remind me of my science studies in school. Anything remotely technical and I struggled. So I’ll keep it simple, as much for you as for me.

In essence, hydroxyls produce oxidants that break down pollutants in the air.

Hydroxyls and hydroxyl radicals generate naturally in the atmosphere. It happens when the sun shines on water vapor in the air. The ultraviolet UV-C radiation strips hydrogen atoms from the water molecules. Negative hydroxyl ions form as a result. They act as an oxidant to break down organic material in the air and render them harmless. And it’s the organic material in the air that is polluting and injurious to health.

Some air purifiers replicate the process to remove organic pollutants.

What is important about the hydroxyl ions is they are remarkably short-lived. Within a second or so they start their air-cleansing chemical reaction. Unlike ozone, they don’t last long enough to accumulate in the home to create a health hazard.

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An ion is a charged atom (single atom) or a charged molecule (two or more atoms bonded together). They are in a charged state because the number of protons and electrons are unequal.

If the number of electrons is more than the number of protons, we have a negative ion known as an Anion. If it’s the reverse and there are more protons than electrons, then it’s a positive ion called a Cation.

The process of radiation absorption called ionization creates an ion or ions. The process can occur by either physical or chemical means. When radiation passes through a material, it creates ions. Some or all the radiation energy disappears during the process. The effect is to change the electrical balance within an atom or molecule. And leaves it in either a negative or a positively charged state.

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In short, an ionizer is an ion generator. It doesn’t collect the charged ions created. It discharges them into the air. These ions attach to airborne particles and in doing so give them a charge. Because of this, they attach to the nearest surface like a wall or furniture. Sometimes the charged particles combine with one another before adhering to a surface.

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The word micron (or micrometer) is often used when talking about airborne particles. One micron is one-millionth of a meter or one-millionth of 39.37 inches. Not visible to the human eye.

Dust particles can have a diameter of 1 micron. Particles contained in fumes can be smaller, even to a tenth of a micron. So this gives you an idea of the task air purifiers have in trapping particles in the air.

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Microorganisms also referred to as microbes. They are tiny single-cell organisms visible only under a microscope. They are the oldest form of life on the planet and exist everywhere. On the ground, in the air, on and inside our bodies, in the food we eat, all over. There are billions upon billions of them. On our hand alone there are more than the number of people on earth. Get the drift, a lot of them.

Microorganisms include all bacteria and archaea (bacteria like creatures). As well as fungi, and protists (algae, amoebas, slime molds, etc.). Also, viruses but there is some debate about whether they are living creatures.

We can’t survive without them because many are beneficial to our lives. But there is a small number that is pathogenic or able to cause disease. And some of those do become airborne. Like mold spores and dust mites that cause allergens. Others cause colds, flu, and other viruses.

They’re not so bad when they are outside the home in the open air. But when trapped inside our sealed homes, contamination levels increase. Higher levels raise the risk of illness. Not just for young children, but the elderly and those with impaired immune systems.

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Earlier I clarified what an atom is. Molecules are the next step up. As the lowest measure of a chemical compound able to take part in a chemical reaction. In other words, a molecule is a chemical.

A molecule forms when two or more atoms create chemical bonds with one another. They can be the same or different types.
A molecule can also be a particle.

I won’t confuse you with the chemical symbols, but molecules come in two sorts.

A simple molecule has one element with two atoms joined. They include chlorine, hydrogen, nitrogen, oxygen, oxide, calcium, and ozone.

Second, there are complex molecules comprised of two or more elements called compounds. Examples of these are water (a bonding of hydrogen and oxygen). And calcium oxide, known as quicklime of burnt lime (a combination of calcium and oxide).

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Odors and Gasses (and Vapors?)

You could question the need for an explanation of these words. Either separately or about them as a phrase. As they have common, well-understood meanings.

But it is important in the context of reviewing air purifiers. That’s because air purifiers vary in their ability to remove these pollutants. You need to know what they mean when marketing blurb refers to removing odors or gasses or both or vapors. Not knowing means you don’t have enough information to make a decision. You could finish up with a unit that is wrong for your circumstance. So here goes.

Gas is one of the four core states of matter. The other three are solids, liquids, and plasma just in case you wanted to know. It’s unique in that it has no fixed shape or volume. The particles in gas spread out to fill the available space. The particles move fast, collide and spread until their distribution is even. Because there is plenty of space between the particles, gas doesn’t have any color. It’s invisible to the eye. If the available space is not confined, gas escapes and disperses into the outside air.

Vapor is a gas. In physics, it’s a substance that’s in a gaseous phase. This gas phase occurs at a temperature that is lower than its critical temperature. Increasing the pressure on the vapor, without lowering the temperature, condenses the vapor to a liquid. It’s when a substance can exist in either a liquid or a solid state.

An odor is a smell. The smell comes from combinations of molecules (chemicals) that float in the air. In particular, these activate our sense of smell. There are other molecules in the air that we can’t smell.

We notice a smell when the “smelly molecules” reach our nostrils. Our olfactory receptors detect it. Olfactory is the word that is all about the sense of smell.

An odor can be either pleasant or unpleasant. At the same time, the molecules causing an odor may or may not be harmful.

What then is important about gasses, vapors, and odors from an air purifier perspective? It’s about what type of molecules or chemicals are present. Some air purifiers are better at removing chemicals or types of chemicals than others. Knowing what pollutant(s) you need to remove is critical.

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Another chemical term. Other words meaning the same thing are oxidizing agent and oxidizer.

It refers to a substance that that can cause another substance to lose electrons. In other words, an oxidizing agent oxidizes other materials and gains electrons. In the process, it’s oxidization state decreases.

Typical oxidizing agents are oxygen, ozone, fluorine, bromine, and hydrogen sulfuric acid.

What does this mean when we’re looking at air purifiers?

Polluted air contains oxidants, the most abundant of which is ozone. But no matter what they are. If the human body accumulates too many oxidants, it creates a disorder called oxidative stress. In short, oxidants are toxic and change or destroy healthy cells.

And this is a major factor in the development of degenerative and chronic illnesses. Illnesses like arthritis, autoimmune disorders, cancer, cardiovascular and neurodegenerative diseases.

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More chemistry. Ozone is a gas in the atmosphere with three oxygen atoms in a molecule. It has a strong odor and is blue in color.

Compare this to oxygen which only has two oxygen atoms, no odor, and no color. What a difference one atom can make.

Ground level ozone results from the chemical reaction between pollutants in the air that come from emissions created by human activity. Such as those from vehicles, power plants and factories.
Ozone is an oxidant and toxic. Like all oxidants, if concentrations reach a high enough level it is harmful to human health.

There was a period when ozone was not understood to be dangerous. And air purifiers were manufactured to produce ozone in excessive amounts for removing pollutants. That time has passed. But there are still products that generate ozone.

So it pays to check if the purifier you are looking at doesn’t produce dangerous levels of ozone. And just as important. Even if it’s at safe levels is it effective at removing contaminants.

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Ozone Generator (for Air)

As the term says. An ozone generator produces ozone to remove contaminants from the air. Ozone is not a by-product. It’s deliberately generated by using UV (Ultra Violet) light or an electrical discharge.

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Photocatalytic Oxidation (PCO)

Photocatalytic oxidation happens when UV (Ultra Violet) light combines with Titanium Oxide. Hydroxyl radicals and super-oxide ions result. These energetic electrons combine with other elements in the air like bacteria and VOC’s. The resulting chemical reaction oxidizes or burns the pollutant. What’s left is carbon dioxide and water molecules. In other words, cleaned air.

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There are often different types of filters installed in air purifiers. And each type aims to remove a particular group of pollutants.

But their effectiveness is impaired if they have to deal with larger particles like hair and dust. This is where the pre-filter comes in.

It’s placed at the start of the filtration process when air first enters the unit. It traps the larger particles. Those, the technology available to small home style air purifiers, cannot destroy. In most cases, either repeatable washing or vacuuming keeps them clean. So replacement costs are cheap.

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Have You Found Any Other Terms?

There may be some I’ve missed. If so, I’d love to hear of any that need adding.

Let me know by emailing [email protected]

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