HEPA Air Purifiers 101



What are HEPA air purifiers ?

HEPA air purifiers are air purifiers which clean the air through the use of HEPA or High Efficiency Particulate Air filters. HEPA filters are high efficiency filters capable of filtering particles up to 0.3 micron in size at 99.97% efficiency. This includes large allergens (pollen and visible dust) as well as smaller allergen in the range of 0.3-5 micron, such as: pet danders, dustmite, mold spores, some bacterias, smaller dust, and fumes.

In addition, they also can filter particles smaller than 0.3 micron, such as some smokes, tiny germs, and so forth, but at reduced efficiency.


How Do HEPA Air Purifiers Work ?

Basically, HEPA air purifiers clean the air by passing the dirty air through the HEPA filter and exhalling the clean air out to the room. Some HEPA air purifiers are equipped with a prefilter so that the big particulates in the dirty air hit the cheaper filter first and leave the HEPA filter to deal with finer particulates. That way, the expensive HEPA filter does not have to be replaced so frequently.

Although HEPA filters already filter out particulates at 0.3 micron or bigger, the majority of particulates (90%) including gases are smaller than that. Sure the smaller particulates (smaller than 0.3 micron)are easier to exhale from the lung, but for people with health problems or with overwhelming number of such fine particulates in the surrounding (for instance: smoke, chemical outgas, pet odor), it helps to have a HEPA air purifier which is equipped with a gas absorbant, such as a chemical or carbon filter. Hence air purifier manufacturers often also include a carbon filter, consisting of activated carbon, to help trap such fine particles. Of course the ability of an air purifier to control odor and smoke also depends on the amount of activated carbon embedded in the unit. Some cheaper air purifiers usually have stripes of carbon, whereas premium air purifiers pride themselves for putting in 5 lb of carbon or more in the unit.

Finally, it is also known that HEPA air purifier's manufacturers sometimes include UV or other germicidal agent such as silver screen in their units to help kill germs. Actually, an UV or germicidal agent is not a priority if the other filters do the good job in filtering small particulates. In this kind of unit, germs will automatically be filtered. In fact, most premium air purifier lines do not have a UV light or other germicidal agent. And yet, they are very effective in curbing dead particulates and live germs alike. The concern of having a UV light is that it can make the unit to produce ozone, a potential lung irritant, as a by product.

In short, the stage of cleaning air using a HEPA air purifier is as follows:

  • Dirty air from surrounding is sucked up to the air purifier unit and is passed to a series of filter by the use of fan.
  • Stage I (optional): The dirty air is passed through a prefilter. Not all HEPA air purifier units has a prefilter, but most have it to reduce the frequency of HEPA filter replacement.
  • Stage II (optional): Some HEPA air purifiers use carbon filter to filter out gases. So once the air is passed from prefilter, it gets to the carbon filter.
  • Stage III: Air is then passed through the HEPA filter.
  • Stage IV (optional): Air is exposed to the UV light to help kill microorganism.


Are HEPA Air Purifiers Safe ?

In contrast to some electronic air purifiers such as ionic air purifier and ozone air purifier, HEPA filter air purifiers are the safest air purifiers you can get. Since it works by mechanical means, there is no ozone, a potential lung and respiratory pathway-irritant, emitted. If you choose the ones with metal casing and non-toxic paint, there will be no outgassing either.



Advantage of Choosing Air Purifier With HEPA filter

  • Safe.
  • It works and has a high efficiency in curbing out lung-penetrating air particles.
  • If you get a premium quality HEPA filter air purifier, there is a big chance that it will help your health problem.


Possible Drawbacks in Owning an Air Purifier with HEPA filter

  • Maintenance cost can be expensive because of the need to replace the HEPA filter periodically.
  • Possible hassle of installing the HEPA filter. You may need tool for changing the HEPA filter, but there are some air purifiers which are very easy to change. If you are DIY-challenged, make sure you get the one which has an easy-to-replace HEPA filter.
  • Noisy. A HEPA filter air purifier needs fan to draw air into the unit and to the filter. The higher the speed, the noisier it gets.


Is Air Purifier with HEPA filter worth it ?

So, is air purifier with HEPA filter worth it, considering the high cost of HEPA filter replacement, especially those that came from the top air purifiers ?

To answer that question, and whether you really need the high end HEPA air purifiers, you have to consider what your needs are. For instance, if you want to buy a HEPA air purifier for addressing a health problem, then you should know how severe the problem is, and what exactly the trigger for your health problem is. Only then you can get a HEPA air purifier which matches your needs.

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