What kind of Air Purifiers are there and how do they work?

What are Air Purifiers?

As the name suggests, they are machines that purify the air by removing airborne pollutants and particles or rendering them harmless. They’re especially helpful for people susceptible to allergy attacks or those who can’t stand the smell of smoke; almost a must-buy for people who live with smokers. They’re also good for removing foul odors and strong scents from vicinity.

How do Air Purifiers Work?

The important components of an air purifier consist of one or more types of air filter and a fan. The fan (or even a system of fans in some models) sucks in air that then passes through the filter. The filter traps airborne particles and pollutants before releasing the purified air back into the room. This process contributes to good air circulation indoors which is beneficial to one’s health. (As a side note, this is why even if opening a window offers the chance to introduce some airborne pollutants into the room, the benefits of fresh air outweigh those of keeping the window shut all the time.)

Air purifiers are categorized after the method or air filters they use to purify the air. Many use one type of filter but some advanced models use a combination of them. These filters include HEPA filters, activated carbon filters, electrostatic filters, and UV light filters. Let’s take a closer look at each of them.

Hepa Filters

There seem to be multiple meanings for HEPA: high-efficiency particulate absorbing air filter, high-efficiency particulate arresting air filter, and the shortest version, high-efficiency particulate air filter. Regardless of which meaning of the acronym you decide to use, the filter works the same.

HEPA filters contain pleated, multi-layered meshes made of fine fiberglass threads that are capable of trapping tiny pollutants in the air as small as 0.3 microns in size. For context, the smallest particles we can see with the naked eye are at least 50-60 microns in size. By drawing in contaminated air with their built-in fans, air purifiers that use HEPA filters can catch pollutants such as pet dander, pollen, dust, dust mites, and some viruses and bacteria. This is particularly useful in households that have children, the elderly, those prone to allergy attacks, and individuals with compromised immune systems.

Additionally, air purifiers that use HEPA filters are considered one of the safer options compared to other types of air purifiers because they don’t produce ozone, which is harmful to the lungs.

They are also one of the most effective choices for cleaning the air, as they have an 87-99% first-pass efficiency rate, which translates to capturing more particles quickly. To maintain their efficacy, it is recommended to replace the air filters after 6-8 months of regular use, or as indicated by your air purifier’s instructions. 

Activated Carbon Filters

If you’ve ever placed a box of baking soda or charcoal in a room to remove awful smells, then you’ve already gotten a taste of what an air purifier with an activated carbon filter can do.

Air purifiers that use this kind of filter are excellent at removing foul-smelling or harmful gasses from the air. They do this by filtering air through a layer of activated carbon (it can also be called activated charcoal). The long story short of how carbon filters work is that they trap pollutants through adsorption—which causes the pollutants to stick to the carbon—as opposed to absorption which traps pollutants within itself, like you’d expect from a sponge. Once a pollutant is trapped onto the surface, it becomes saturated and won’t be able to trap any more pollutants in that area. This is why carbon filters with a greater surface area can trap more pollutants and why carbon filters need to replaced regularly.

They’re normally used to get rid of volatile organic compounds (VOCs) that are released from common household products or home activities like cleaning or cooking. You may want to consider getting an air purifier with a carbon filter in situations such as:

1. Using household cleaners that contain chemicals like ammonia, chlorine, and phthalates
2. Living in an area with a lot of motor vehicle traffic, such as city building next to a frequently-traveled road
3. Using paint, aerosol sprays, or a strong-smelling air freshener
4. Cooking dishes that emit strong smells of cooking oil or spices

To keep your air smelling fresh and clean, and to ensure your carbon filter air purifier gives you the best results, replace your filters regularly as indicated by your air purifier’s instructions.

Electrostatic Filters

Electrostatic filter air purifiers use the power of static electricity to pull pollutants out of the air. By generating electric fields that give the particles a certain charge, the air purifiers can trap them in the filters that have the opposite charge. The effect is similar to that of magnets sticking to each other via attraction of opposite charges. Through this method, this kind of air purifier is good for clearing the air of dust, pet dander, and mold. 

There are some drawbacks though. Electrostatic filter air purifiers only have a 60-80% first-pass efficiency rate and take longer than HEPA filter air purifiers to improve indoor air quality, and even then, it still won’t always reach the levels HEPA filter air purifiers are capable of. They also can’t remove VOCs or gasses, so don’t expect an electrostatic filter air purifier to make your air smell better. Furthermore, because they generate an electric field, they can produce harmful ozone, which is possibly its biggest weakness.

Nevertheless, they offer a lower overall maintenance cost as the electrostatic filters need to be cleaned rather than replaced completely. If you’re fine with a little bit of extra upkeep and cleaning out the filter somewhere between every two weeks and one month to ensure its effectiveness, you could stand to make some savings.         

UV Light Filters

Ultraviolet (UV) filters harness short-wave ultraviolet light (UV-C light) to inactivate airborne pathogens and microorganisms such as mold, bacteria, and viruses, and in doing so, render them inert. The technology is also referred to as UV germicidal irradiation (UVGI). This kind of UV light is stronger than the kind of UV light from the sun that can cause sunburns. Indeed, it destroys DNA, which is why is it so effective in killing viruses and single-celled organisms like bacteria which rely on their DNA to replicate. This is the same reason UV light is good for disinfecting surfaces. 

In the case of UV filter air purifiers, they draw in contaminated air and expose it to UV lamps inside, which essentially disinfects the air via UVGI. While theoretically capable of rendering some microorganisms harmless to humans, many factors come into play that can affect it’s effectivity:

•  Whether the pollutants even come into contact with the light
•  How much of the light they’re exposed to
•  How long they’re expose to the light
•  The strength or level of ultraviolet light emitted

It is also important to note that UV filter air purifiers only disinfect the air and damage microorganisms. That doesn’t necessarily mean they trap those pollutants. This translates into being unable to fully remove all allergens, fumes, odors, dust, pet dander, smoke, and molds from the air. They can’t destroy volatile organic compounds (VOCs) either, so be aware of the limitations of this kind of air purifier if it doesn’t support additional filters.

Clean air is so vital that having any kind of air purifier can immediately provide noticeable health benefits. People with allergies or chronic respiratory problems can literally breathe easier with reduction of attack-causing triggers. Those with weakened immune systems can enjoy significantly safer air. Newborns that haven’t developed their immune systems yet and that are susceptible to contaminants in the air can be protected. The list of people whose lives could be improved by having an air purifier in the home is endless.

For an oversimplified way to help in your decision-making process, you could consider the different kinds of air purifiers this way:

• HEPA filter air purifiers are good all-around choices that excel at removing most particles from the air.
• Carbon filter air purifiers are especially good at removing bad odors and foul smells.
• Electrostatic filter air purifiers are reasonably effective and don’t require replacement of filters, which can save on costs.
• UV light air purifiers are great for disinfecting but may struggle to remove the pollutants from the air without additional kinds of air filters.

With all this information at your disposal, you’ll hopefully be able to choose the right air purifier for your needs and start enjoying the many health benefits of cleaner, safer air!