HEPA Air Purifier Technology

Air Purifier technology breakdown and details

In the air filtration industry filters are technically divided into several categories:

  • mechanical (coarse filter) - to trap large particles;

  • absorption (coal) filter - for trapping odors and toxins;

  • electrostatic filter (they are air-ionizing and draw pollutants to trap it);

  • HEPA filter (to capture even the microscopic particles, including allergens);

  • photocatalytic filter (ultraviolet), designed to disinfect the air, as well as oxidize harmful compounds into carbon dioxide and water.

There are a large number of models of air purifiers on the market. Therefore, we decided to explain everything: starting with their device and ending with the types of filters with which they can be completed.

Air Purifier. A Basic Option

The easiest way to clean the air in your home is to run all of it through a coarse filter and a carbon filter. Thanks to this scheme, it is possible to get rid of unpleasant odors and to remove relatively large particles of contaminants from the air (like large dust particles or animal hair). These models are inexpensive, but they do not make any special effect on the air. After all, bacteria, allergens, and microscopic particles still remain unfiltered.

In some cases, an ultraviolet lamp is added to a purifier of this type. It works like a hospital quartz treatment, i.e. disinfects the air passing through it. But this solution is also a compromise since a large stream of air cannot be effectively "processed" by ultraviolet in the short time it passes through the chamber with the lamp in it.

Electrostatic Air Purifiers

In these devices, the principle of cleaning is slightly more complicated: the air is driven through the electrostatic chamber of the purifier, where contaminated particles are ionized and attracted to the plates with opposite charges. The technology is relatively inexpensive and does not require the use of any replaceable filters. Unfortunately, these cleaners can not boast of high performance. Besides, it is known for high ozone emissions, that are practically uncontrollable.

It would be strange to deal with one type of pollution that is actively saturating the air with another. Therefore, this option is suitable for cleaning a small room that is not subject to severe pollution.

HEPA: Filtering the Air Carefully and Thoroughly

HEPA is a technology that came from the nuclear industry. Contrary to popular belief, HEPA is not a trademark or a specific manufacturer, but an abbreviation of High-Efficiency Particulate Arrestance.

HEPA filters are made of fiberglass material with randomly. Pollution particulate is caught in three main ways:

  1. Inertia: particles with a diameter of more than one micron enter the filter along with the air flow and cannot go around an obstacle. As a result of inertial motion, they get stuck in the filter;

  2. Diffusion: light and small particles (with a diameter of fewer than 0.1 μm) due to their chaotic motion are deposited on the filter fibers, while the rest of the air flow flows around the obstacle and cannot pick them back up;

  3. Meshing: particles too large for diffusion and too small for inertia fly with the main air stream. However, some of them still cling to the fibers of the fiberglass net and remain there for good. New particles catch on it, and so the process goes on. By the way, due to the sticking of the particles the filter remains effective for long periods of time. The particles that already got "caught" help get new pollution particles to be captured.
HEPA air purifiers are highly efficient filters for indoor air. Their main purpose is to remove fine particles from the air, including PM 2.5 and PM 10 (with a diameter of less than 2.5 and 10 microns, respectively). HEPA is neither a brand or a trademark, but a grade of filters. The requirements for HEPA filter have been strictly outlined and are continuously maintained by international standards, namely by EN 1822-1: 2009 and EN 1822-1-2010.

HEPA purifiers are made to remove all types of dust particles, allergens of sorts (pollen, fuzz, fur, bacteria, mold spores, dander, smoke, perfume scents, kitchen odors, etc.) from the airflow.

The HEPA standard, in its broadest sense, has several filtering classes. The most common (and cheapest) of them is E10, and it implies the efficiency of trapping particles only 85% (in fact, only using inertia). The next one is E11 (95% efficiency) and E12 (99.5% efficiency). In fact, the filters ranging from E10 to E12 should be called not HEPA, but EPA. However, standards in various countries allow manufacturers juggle standards and names sometimes. With that being said, filters starting from E12 in efficiency can easily be recommended for purchase, as their efficiency is already at a sufficient level.

The next class is H13. This is a true HEPA that involves the collection of 99.95% of contamination particles from indoor air. That means - almost everything is "caught" from the air flow. Further increase in class does not make sense in everyday living conditions, because class H14 assumes an efficiency of 99.995%. The next group - ULPA, starting with class U15, means the efficiency of 99.9995%. So, as you may have already guessed, the difference is going to be very hard to perceive.

Air Purifiers Without Replaceable Filters

No matter how effectively the HEPA filter works, it must be replaced as often as the manufacturer indicates. As a rule - at least once a year. In addition, HEPA filters are mostly disposable and cannot be simply washed with water. Considering that they are expensive, you can try to save money and solve the problem of air humidification at the same time. There is a class of devices that allows air cleaning through "washing".

Cleaning occurs due to the passage of air flow through water-wetted discs or a cloud of small droplets in this case. The result is the air gets saturated with moisture and gives off large particles of pollution. Unfortunately, the level of purification by a water filter like that is not very high (at the level of HEPA E10, not more). However, if you need an air humidifier first and foremost a solution like that would be totally justified.

A Photocatalytic Air Filter

The air comes through a coarse filter enters the unit with a photocatalyst (titanium oxide). There - under the influence of ultraviolet light harmful particles are oxidized and decompose.

The scheme is as follows:
It is believed that a filter like this fights pollen, mold spores, gaseous pollution, bacteria, viruses, and the like very well. Moreover, the effectiveness of such a cleaner does not depend on the degree of contamination of the filter, since dirt does not accumulate there.

The effectiveness of this type of purification is also questionable at the moment. Since photocatalysis happens on the outer surface of the filter only. Significant air purification requires coverage of several square meters with an intensity (power) of ultraviolet light of at least 20 W / m2. These conditions are not met in any of the photocatalytic air purifiers manufactured to date.

Whether this technology is recognized as effective and whether it will be upgraded - time will tell.


One of the important indicators of the operation of any air cleaner is the speed of air purification in the room (CADR), which is determined by the product of the filtration coefficient and the volume of air passed through the filters. Usually, this indicator is set for several types of pollution and is accompanied by certificates from various research centers and associations.

Since we do not live in completely sealed, but in ventilated rooms, a good device must have time leeway to clean the air before we breathe it. Therefore, it is considered that an air purifier should take the entire volume of air in the room through its filters at least 2 or 3 times within an hour. Accordingly, the recommended rate of CADR for a room of 20 m2 and a ceiling of 2.7 m should not go below 100 m3 / h.

How is HEPA built and working?

HEPA filters are machines with a multi-layer air filtration system. Each unit has a pre-filter.

The prefilter is installed as a "topper" for the whole machine. All the dust and dirt is deposited on the prefilter. The bigger particles stop before they enter the machine, thus keeping the machine working longer.

It is basically an inexpensive item that will make your expensive item serve for much longer. The protective electrostatic filter and the device itself remain clean. Once a month, we throw out the old prefilter, change it to a new one. The device itself can no longer be cleaned. The procedure takes less than 2 minutes.
A pre-filter can be called different names, but in its nature, it is an add-on screen for an air filtering machine, that has a felt-like texture and feel. A pre-filter (also known as flair screen) can be framed in or built into the shell of the purifier and be the first stage among other purifying layers of the machine.

Normally a pre-filter will look something like this:

Does HEPA take care of unpleasant scents?

If our customer desires to get rid of any or every odor in the kitchen or bathroom. If the home has a pet and you prefer to not be aware of the pet's routines. If you have a smoker at home a number of people with a variety of habits, charcoal filters (also known as activated charcoal filters) may be your answer. Normally they look something like this:

Charcoal filters are the ones that are responsible for odor elimination. If you live in a farm and have livestock roaming around, you also may be bothered by the chemicals that are thrown over the fields or by the hay fever and pollen that comes with it.

People who've used the charcoal filters for a while witness up to 89% improvement in odors coming from the living room, kitchen, pet areas, painted walls, closets with sportswear or lavatory rooms. Charcoal filters work as powerful odor absorbers from anywhere in the house. These filters are absolutely non-toxic and hypoallergenic. The sole fact that they are replaceable makes it perfect for people who are conscious of "geriatric filters". The older filters that are replaceable, but have not been in a while tend to become harbors for bacteria, having accumulated a lot of gunk from the air. Stay wary and replace your charcoal filters on a regular basis. If you have doubts about the timing and the ways they can be replaced, call in Ecoquest maintenance technician and appoint the time for a visit.

Does HEPA air purifier help with wildfire smoke and pollen storms?

Customers whose home air deals with severe environmental issues, like massive pollen storms and wildfires asked Ecoquest for a solution. So we've come up with harsh environmental pads.

These extra thick pads take out the harshest of allergens and contaminants from the air in your home. They are replaceable and will prolong the efficiency of your air purifier if applied regularly.

What does HEPA clean out from the air I breathe? It does not feel too dirty to me

The annual Green Week Conference that takes place in Brussels is the actual gathering of European environmental policy enthusiasts. "Clean Air for All" was the theme of the conference in 2013. Amongst everything else, participants were invited to view an exhibition of an award-winning science photographer, Stefan Diller. He presented the public with Scanning Electron Microscope (SEM) images of microscopic pollutants and allergens shot in micrometer range. A variety of microscopic pollutants that surround us, such as diesel soot, pet dander, pollen spores, and dust were depicted on his photos. The idea behind the exhibit was to visualize the invisible world of air pollution. The pictures serve a great visual for those who have been suffering from the bad quality indoor air or have been considering getting an air purifier.

Take a look at mold spores for instance:
After having seen this and the other pictures during the exhibition, conference authorities have concluded that air pollution does not stop at borders and it is a globally important subject.

Indeed, Ecoquest knows that lives are being cut short due to air pollution. People with chronic respiratory conditions suffer annually, at least two times per year, due to "hay fever" or respiratory allergy, medically speaking.

Allergies, Bronchial Asthma and other Respiratory conditions that will benefit from Air Purification

According to AAFA, 1 out of 13 people in the USA suffers from a type of asthma. Bronchial asthma sufferers as well as people who are sensitive to ragweed (Ambrosia) pollen, poplar and dandelion fuzz, birch pollen, cedar, oak and pine pollen, walnut and elm. If you are a pollen allergy sufferer, your immune system sees pollen as a foreign invader and forms an antibody to fight it. Histamines, released by your blood in the process of your nasal tract interaction with pollen, cause the following symptoms: runny nose; sneezing, itchy eyes, ears, and mouth; red, swollen, watery eyes. Asthma and Allergy Foundation of America recommends air purifying units all over your home among other tips to survive the allergy season.

The following respiratory conditions can be caused by allergens, worsened by their impact or triggered by them:

  • Asthma

  • Chronic Obstructive Pulmonary Disease (COPD)

  • Chronic Bronchitis

  • Emphysema

  • Lung Cancer

  • Cystic Fibrosis/Bronchiectasis

  • Pneumonia

  • Pleural Effusion.

An Ecoquest air purifier is a way to get around mold spores in your indoor air. Besides mold, a HEPA air purifier is able to filter out a set of allergens from average home indoor air:

  • pet fuss, fur, danger, scent;

  • human hair, dandruff, shedding skin, scent;

  • pollen of all sorts from outside;

  • dust and dirt particles floating through the air;

  • kitchen, cupboard and toilet odors roaming around the house;

  • cigarette smoke or any other kind of smoke in your home.

Various Conclusions

Photocatalytic filters seem to be the most promising at the moment, as they pick up small contaminants and do not require the purchase of replaceable elements. However, the real effectiveness of this technology is still very questionable. So we have but trust HEPA most. Residents of megalopolises, where motor transport and industry define the "ecology", need to consider getting air purification units for every room in a home. There are a number of studies that talk about the role of fine particles in the development of degenerative brain disorders, including Alzheimer's and Parkinson's. According to MIT, about 200 thousand people die every year due to air pollution in the United States. The various diseases associated with seasonal allergies, allergies to dust (more precisely, to dust mites) and mold are aloof. It looks like air purifiers are a good enough solution as of today.
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