Air Purifier Filters – A Guide


You’ve decided you want to invest in an air purifier? Rad. But that’s only the first decision in a line of many you’ll need to make – because now it’s time to decide what kind of air purifier is right for you and your specific air issues.

Before you pull out your wallet you should understand your options, filter-wise. Different types of air purifiers have different strengths and weaknesses, and much of it comes down to filter type. In other words, the type of air filter in the air purifier you buy will determine how well it works for you needs.

Here’s a recap of the four main types of air purifier filters available, to help you make this decision.


HEPA Filters

HEPA filters are the gold standard for air cleaners today. HEPA stands for “High Energy Particulate Air”; in order to be classified as HEPA, the filter must meet a series of standards set by the United States Department of Energy. These filters capture a minimum of 99.97% of pollutants at 0.3 microns – in other words, they capture the smallest, most harmful particles.

That’s important, because when it comes to pollutants, the stuff we can’t see is the stuff that tends to hurt us the most. When a particle is 0.3 microns, it can sneak past the tiny hairs that line our throat – effectively dodging our throat’s best defense mechanism against invaders.


By LadyofHats [Public domain], via Wikimedia Commons

HEPA filters can capture particles that are 25-50 times smaller than what the human eye can see. You’ll often hear allergists and doctors recommend HEPA air purifiers above other types, because of reasons already discussed.

The drawback to HEPA filters is cost. They tend to cost more per year in replacement filters and electricity than some other options. It can add up over time.

HEPA filters also are not every effective, on their own, at removing chemical fumes, cigarette smoke or other odors in your home. Why, you ask? HEPA filters can be stitched so finely that they miss larger particles, like odors. That’s why most HEPA air purifiers also contain a carbon filter; think of it like a tag team – the HEPA tackles the small stuff, and the carbon filter tackles the odors.


Ionic Filters

Ionic filters are like something straight out of The Jetsons. The air purifiers emit electrically charged ions into the air that then attach themselves to dust, mold, pollen and pet dander particles (to name a few). Once the ions attach to the particles, it charges them, too, so that they will be attracted to and attach to one another. This will make the attached particles larger and heavier, which then makes them settle faster. It also makes them clingier to surfaces like walls, floors and furniture.

The ionization process by itself will not capture any particles or eliminate them from the room. Mold that it ionizes can still grow and spread and vacuuming/dusting can still stir up the particles that attach to walls and furniture. That’s why air purifiers that utilize an ionization process will also feature other filters to do the clean-up work.

The ionization process by itself will not capture any particles or eliminate them from the room. That’s why air purifiers that utilize an ionization process will also feature other filters to do the clean-up work.

Now, there are a few reasons why ionic air purifiers may not work best for some people. The ionization process produces ozone as a byproduct – albeit in very small amounts. But this is something you need to consider, particularly if you have an existing respiratory issue.


Ultraviolet (UV) Filters

These are a fairly new technology in the world air purification, and they work in a pretty neat way. These filters use UV light to destroy bacteria and other pathogens by breaking their bonds on a molecular level in their DNA. It achieves this by emitting electromagnetic radiation, and doesn’t actually filter the air to destroy the particles, just lays in wait until they pass by and then boom! Pathogen destroyed. It’s all very Stars Wars-like.

That is, if you buy into the hype. Many people don’t, and for good reason. There are a lot of questions about whether UV air purifiers circulate air in a way conducive to destroying pathogens and other invaders. Many experts believe UV filters are more bark than bite – in other words, the process sounds neat, but it may not be effective.


Carbon (Charcoal) Filters

If you’re looking to eliminate odors, this is your filter. Carbon filters are made of activated charcoal, which attracts pollutants and traps them in large pores on the surface of the charcoal. These types of filters remove gases, odors and chemical toxins from the air. These types of filters are often used in combination with others in order to decontaminate the air.

The down side to carbon filters is that they will not remove dust or other allergens from the air, nor will they remove micro-organisms like mold. They are, however, highly absorbent and capture a lot of the fumes and odors that other filters will not, such as cigarette smoke. They also won’t release the contaminants back into the air once they’ve been trapped by the charcoal.


Photo credit: sacks08 via Flickr CC License


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