Air purifier glossary

1. What is HEPA?

HEPA air purifier is one of the most popular and effective technologies for cleaning air available today.

HEPA air purifiers are those that cause air to pass through a specially-designed filter called HEPA, which stands for High Efficiency Particulate Air.  These HEPA air purifiers are designed to remove 99.97% of all pollutants that are 0.3 microns or larger.  For reference, 1 micron is 1/100th the width of a human hair!

HEPA filtration technology was developed by the US Atomic Energy Commission to filter our radioactive "dust" and materials from the air.  They have been proven to be very effective at removing dust, pollen, mold, dust mites, bacteria, and other allergens.  Another benefit to HEPA air purifiers is that once the particles are "captured", they are not released again back into the air.

HEPA air filters look like most other air filters you've seen, many have a pleated media, separators, wet laid filter medium, edge seal, a sealant and are contained in a rigid frame. By their nature, HEPA air purifiers do not lose their efficiency over time although they do have the potential of becoming clogged and blocking airflow.

If you are considering purchasing an air purifier that uses HEPA technology, make sure the unit has a pre-filter. A pre-filter filters out larger particles (1 micron and larger) before they reach the HEPA filter. This extends the life of the HEPA air purifier, which can be expensive.  Most HEPA filters will last 2-5 years.

Overall, HEPA air purifiers are very effective at what they are designed to do; which is to clean your air. These types of purifiers have become very popular and are being used increasingly in hospitals and sensitive-equipment manufacturing plants. Many experts in the field of air purification prefer HEPA technology over all others.

2. HEPA air purifier drawbacks.

Like any air cleaner technology, HEPA air purifiers do have their drawbacks, although they are minor. First, HEPA filters cannot capture pollutants that are smaller than 0.3 microns. Things like viruses, odors, and gas molecules are not effectively treated.  Also, because air must pass through the filter, it can be difficult to clean a very large room with a HEPA filter.

3. What’s Negative Ionizer?

Concentration of Negative Ions in Different Environments


Concentration *


95,000 – 450,000

Mountains, seashores, breezy forest

50,000 – 100,000

Breezy country meadow

5,000 – 50,000


100 – 2000

Rooms and offices

40 – 100

Rooms with Air Conditioner

0 – 20

*Approximate Concentration of Negative Ions per cubic centimeter (cc3)

Ionic air purifiers that use this technology emit negative ions that seek out and "ground" positively charged particles such as dust, smoke, and fumes.  The particles, once charged, then stick to furniture and the floor. They must be removed by vacuuming or else they are re-introduced into the air through movement.

4. How do negative ions remove pollutants from the air?

Negative ions help freshen and purify the air by causing allergens such as pollen, mold spores, dust, and animal dander floating in the air (which have either a neutral or a positive charge) to be attracted to and stick to each other, forming 'clumps' (because opposite charges attract). These clumps of particles then become heavy enough so that gravity can pull them down to the floor, where they can be vacuumed up, rather than staying in suspension where they can be breathed in and cause allergic reactions.

As a result, they become too heavy to remain floating in the air, and fall harmlessly to the ground, where they cannot find their way into your respiratory tract.

At this point, even if they are inhaled before falling out of the air, these now larger particles are able to be intercepted by the "filters" of the upper respiratory tract, due to their increased size.

5. What is Electrostatic Precipitator(ESP) air cleaner?

Electrostatic Precipitator (ESP) air purifier works by charging particles with a negative charge as they come into the purifier. Positively charged metal plates are also present in the unit. The newly charged particles are then "attracted" to the oppositely charged plates where they are trapped. The metal plates must be cleaned often in order to remove the particles. What’s more, such Electrostatic Precipitator (ESP) Air Cleaner also kills bacteria, mold spores and viruses in the air it cleans with its powerful electric field.

6. What is the advantage of Electrostatic Precipitator Air Cleaner?
The most advantage for Electrostatic Precipitator Air Cleaner is its strong and entire purification efficiency to particulate, dust, bacteria, virus, smoke etc. without any replacement cost, its Electrostatic Precipitator only needs to be cleaned by running water.

7. What is Photocatalyst(PCO) technology?

UV air purifiers are very effective at neutralizing airborne pathogens that other air cleaners miss

It's no secret that UV light is one of the most effective ways to reduce, control, and sterilize airborne pathogens like germs, viruses, and bacteria.  UV air purifiers generally utilize a germicidal UV lamp in addition to other cleaning technologies, such as HEPA filters or ionic machines.  The UV light in UV air purifiers is the only way to destroy viruses and render them harmless.

UV air purifiers work by passing air through intense UV radiation.  This radiation damages the DNA of many microorganisms which leaves them unable to reproduce.  Any germ, virus, or bacteria that is unable to reproduce is then harmless to humans and pets.

The reason many air purifiers include a germicidal UV lamp is to destroy microorganisms like viruses that are too small to be captured by HEPA filters and other purification technologies.

The benefits of UV air purifiers are well documented and are commonly used in hospitals to prevent spread of infectious diseases.  In fact, the CDC (Centers for Disease Control) recommend UV light radiation as a method to prevent illness and disease-- not a bad endorsement!

When considering a UV air purifier, it is important to keep in mind that UV light has no affect on particulates such as dust, smoke, gases or chemical fumes.  As a stand-alone technology, UV sterilizers will also have no affect on odors.

So, if you do choose to purchase one of the many UV air purifiers on the market, make sure that the UV light is combined with other filtering methods to ensure that all pollutants are cleaned, not just those that are alive.

8. What’s PCO(Photocatalyst Oxidization)?

Photocatalyst (TiO2) is a semiconductor that has strong oxidation. Shining of light source can stir up oxidation-reduction reaction on its surface, and the surface will release free radicals (·OH) and (·O ), at the moment, chain degradation reaction occurs between the free radicals and kinds of contaminant and bacteria each other. And the reaction can realize the functions of air purification, anti-bacteria, anti-dirtiness and deodorization, hydrophilic nature, and so on.
Utilized in air purification, it can efficiently decompose and eliminate many kinds of organic and inorganic materials and gases in the air.
Coated on nickel foam filter, it is efficient for long consumed without declining with the time, and very convenient for maintenance--the TiO2 nickel foam filter can be washed without any destruction of its efficiency.

Purification technology
HEPA filter
1)   Traditional purification method, efficient to remove contamination down to 0.03um.
2)   Safe and no any by-product or electronic danger.
1)  No efficiency to contamination smaller than 0.03um, for example: voc etc.
2) High replacement cost.
3) Only purify air which put through machine.
Negative ion
1)  Negative ions disperse throughout the room and cause particles to drop down to ground.
2)  Fresh air and improve spiritual status.
Trap particles onto ground or tables, thus, ground or tables should be cleaned frequently.
PCO technology
Strong purification technology to virus, bacteria, germs etc. 
1) High replacement cost for UV lamp.
2) The Photocatalyst (TiO2) is easily coated by dust over some time and efficiency will decrease.
Most strongest and efficient purification to various contamination: particulates, dust, bacteria, virus, germs, VOC, smoke etc.
1) Complicated manufacturer technology.
2) Create ozone as by-product easily.

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