How Does an Air Purifier Work (Detailed Guide By Professionals)

With the rise in outdoor air pollution, there is also an increase in indoor air pollution. And, to your surprise, poor indoor air quality can be at least five times more harmful than the outdoor one, leading to various kinds of respiratory diseases like asthma, and in some cases, even cancer. This risk of developing severe lung diseases has significantly increased the demand for indoor air purifiers.

But, before you step on the bandwagon and purchase one for your house, do you know what an air purifier is? Does it really work? And, if it does, what is its working mechanism? Fret not, as we have answered all these questions and much more in our article below. So, without much ado, let’s get started.


What is an Air Purifier?

Air Purifier

An air purifier, also known as an air cleaner, is a device that is designed to improve indoor air quality by removing the pollutants from the air in your room. You can find these as small, portable units or as larger ones that can be attached to a

HVAC (Heating, Ventilation, and Air Conditioning) unit or to an AHU (Air Handler Unit), commonly found in industrial, medical, and commercial places.

These are especially beneficial for people suffering from allergies, asthma, or other respiratory issues. And, if you are exposed to secondhand tobacco smoke, these will help eliminate that as well. In short, an air purifier is a device that enables you to breathe cleaner air by limiting the spread of hazardous allergens. It also prevents any allergy or diseases like asthma.

Though air purifiers benefit people with underlying respiratory conditions, these can also be used as a preventive measure by those wishing to protect themselves and their families from indoor air pollutants.

How Do Air Purifiers Work?

The working mechanism of an air purifier is actually pretty straightforward. It uses a fan to pull in the air inside your room, which then passes through a filter or a series of filters. When the polluted air passes through these filters, the harmful airborne contaminants like dust particles, bacteria, pollen, etc., are trapped by the filters and removed from the air.

Once the air is purified, it gets circulated back in the room by the air purifier. This whole set up is repeated numerous times in an hour to provide clean, fresh air for a healthy indoor environment.  This is the most basic functioning of an air purifier. The process can vary depending on the different types of air cleaners, ranging from HEPA filters to ionizers.


Types of Air Purifiers

Types of Air Purifiers

As we have discussed above, there are several different types of air purifiers, having different working mechanisms. They also differ in how they treat pollutants in the air. Let’s discuss some of the most common types of air purifiers or air purification technologies.

High-Efficiency Particulate Air (HEPA) Filter

High-Efficiency Particulate Air (HEPA) Filter

A True HEPA filter is the most talked about and famous air purifier type throughout the world. The HEPA filter is nothing but a mechanical filter that is designed to get rid of the airborne pollutants from the air inside your room. They do so by allowing the air to pass through dense fibre arrangement, which then traps the contaminants like dust, pet dander, pollen, etc.

HEPA filters are highly efficient in removing pollutants from the air. They can filter around 99.97% of airborne particles up to 0.3 microns. The fibre used in them has to be of certain industrial specifications for optimum performance. Also, over time HEPA filters can become less efficient as the pollutants can choke the filter. Therefore, these must be replaced every twelve to eighteen months for proper functioning.


Activated Carbon Filter

Activated Carbon Filter

Many air purifiers also come with a carbon filter that uses charcoal or activated carbon to remove any foul odour, gases, or volatile compounds from the air. It does this by the process of adsorption in which a particle is trapped on the surface of another particle.

So, when the air passes through the carbon filter, the gas molecules or other chemicals are adsorbed into the carbon pores. Bigger-sized particles get stuck onto the pores. There is also an electrostatic attraction that sucks some molecules into them. While other particles react chemically and bond to the activated carbon. This is how odours are removed from the air, and fresh air is circulated back into the room.


Photo Electrochemical Oxidation (PECO)

Photo Electrochemical Oxidation (PECO)

One new technology that has made its way into the indoor air purification market is Photo Electrochemical Oxidation or PECO. It is designed to kill the contaminants at the molecular level itself. In this, a catalytic reaction is activated when the light shines on the surface of the filter.

Harmful organic contaminants like allergens, mold, volatile compounds, etc., are then converted into substances like carbon dioxide and water, which cause no harm. The highlight of this technology is that once the pollutants are broken down, they cannot be released into the air again. However, PECO filters still need to be changed frequently for proper catalytic reaction and optimum air purifier performance.


Ultraviolet Light

The Ultraviolet air purifiers are the ones that expose the air filled with bacteria and viruses to UV or ultraviolet light. The idea is to disinfect the air by deactivating or destroying the bacteria and viruses. It is pretty helpful in hospitals and other areas when one has to continuously disinfect the equipment.

However, in-home settings, its advantage is a bit exaggerated. It doesn’t work as efficiently for the very simple reason that bacteria and viruses have to be exposed to UV light for a considerable amount of time before they are destroyed. And, this doesn’t happen with UV light air purifiers.

Also, exposure to UV light can cause skin damage, which is why we don’t recommend using this technology for home purposes.



Ionizers or ionic air purifiers use electric charge, which releases negative anions to attract positive cations of the pollutants. This technology doesn’t precisely remove harmful contaminants from the air but only force them out of the air and allow them to settle on other surfaces like walls, ceiling, etc. This can be beneficial in hospitals but not in home settings, as the pollutant build-up inside the house raises tremendously with this technology.

Also, ionizers can produce ozone, which in enclosed settings is extremely harmful. It has the potential to irritate the respiratory tract, cause asthma, or even be fatal at large concentrations. Therefore, ionizers must be avoided for household purposes.


Ozone Generators

Ozone generators are not air purifiers in real terms. These are merely designed to modify the oxygen molecules in the air and turn them into ozone. There are claims that ozone generators can help neutralize some pollutants, but ozone itself is a toxic gas. Since it is not very stable, it can react with other substances and cause respiratory issues.

Therefore, experts are against the use of ozone generators for household purposes as indoor ozone build-up is even more harmful. It is only recommended that these are used for professional cleaning. Also, make sure that while using an ozone generator for professional cleaning, no person should be there, and space is well ventilated after usage.


Why Do You Need an Air Purifier?

Why Do You Need an Air Purifier

If you are still wondering whether you need an air purifier or not, we have made it easy for you by listing down a few reasons why air purifiers are the correct choice for your home. Let’s have a look at them.

Air Purifiers Ensure You Breathe Cleaner Air

As we know that indoor air can be up to five times worse than outdoor air in some instances, a good quality air purifier will ensure that the pollutants are removed, and you breathe clean air. It is especially beneficial for people with allergies, lung issues, or low immunity.


Air Purifiers Help Remove Up To 99% of Airborne Pollutants

There are minute airborne pollutants like pollen, bacteria, etc., that stay in the air and cause several diseases like cold, flu, allergies, etc. Air purifiers are designed to get rid of these airborne contaminants, thereby keeping you healthy.


Air Purifiers Eliminate Unpleasant Odours

Unpleasant odors are not only a big turn-off but also can make people feel nauseated. Imagine entering a house that has all sorts of odours filled in the air, disgusting, right? Air purifiers help you get rid of these odors and leave your indoor environment smelling fresh and clean.


Air Purifiers Trap Dust Particles

Indian houses cannot escape the dust. No matter how much you clean your home, you will always see the dust settling here or there. This is where an air purifier helps a lot as it traps dust particles in the air itself, even before it gets the chance to rest on your furniture. This reduces the dust build-up in your house, and if you are allergic to dust particles, it will be highly beneficial for you. We also recommend using a vacuum cleaner along with an air purifier for dust accumulation.


Air Purifiers Help Combat Airborne Pet Allergens

Though pets are adorable, they still have their own downsides. You might love them a lot, but your cute pet releases a whole lot of airborne allergens like pet dander, fur, and also odour. An air purifier takes care of all of these and allows you to love your pet without worrying about the allergens.


Air Purifiers Trap Smoke

Smoke while cooking food, burning wood, or even smoking cigarettes can be harmful to your health. A lot of carcinogenic pollutants are released in smoke which, when inhaled, can cause various health issues, ranging from asthma to cancer. Air purifiers help trap the smoke particles from the air and save you from its ill effects.


Air Purifiers Remove Seasonal Allergens

Seasonal allergies are a nuisance. They make breathing difficult and come with other issues like coughing, sneezing, etc. Air purifiers work extremely well in removing these allergens from the air inside your house and help you breathe better.


Air Purifiers Prevent Germs or Airborne Diseases From Spreading

Cold, flu, and even the novel coronavirus spread through the air. A good quality, True HEPA air purifier with a UV bulb will help in catching and neutralizing more than 99% of these airborne germs. This, in turn, will help in preventing or spreading airborne diseases in your family.


Air Purifiers are Good for Your Lungs

When you are exposed to dust, fur, pollen, or other allergens for a long time, there are high chances that you might develop breathing or other health-related issues in the future. However, a high-quality air purifier will help you prevent these problems and keep your lungs healthy for a long time.


Air Purifiers Fit Just About Everywhere

Air purifiers are available in a variety of sizes, ranging from small portable ones to larger units fitted in AHU or HVAC. These come with plenty of features as well that are designed according to your needs are requirements. You can place them in your room, lobby, office, etc., and enjoy clean air.


What to Look For in Your Air Purifier?

Before you purchase an air purifier for yourself and your family, you must have a clear understanding of what makes a quality air cleaner. We have listed a few pointers that you must keep in mind before investing in an air purifier. Let’s have a look at them.

Get an Air Purifier with a HEPA Filter or HyperHEPA Filter

You must always go for air purifiers with HEPA filters or HyperHEPA filters. Though the name sounds a little alien, its working is quite simple. High-Efficiency Particulate Air or HEPA filter are designed to trap airborne pollutants from moving air with the help of heavy, random positioning of fibres. This is one of the most effective methods in reducing indoor air pollution. The HEPA air purification technology can filter around 99.97% of airborne contaminants up to 0.3 microns.

Building upon the HEPA technology, the HyperHEPA filter provides even better filtration, removing around 99.5% airborne contaminants up to 0.003 microns. These are actually 10,000% smaller than the 0.3-micron particle size, which boasts of its efficiency. Therefore, always invest in a HEPA filter or HyperHEPA filter air purifier for the best indoor air quality.


There Must Be No System Leakage

Though HEPA filters are highly effective, the housing system of many air purifiers might not be airtight, leading to leakage of polluted, unfiltered air around the HEPA filter. This reduces the overall efficiency of the device significantly. Let’s say that the brand promises around 100% efficacy in removing airborne particles from the air in your room.

But, due to leakage, the overall efficiency of the purifier can come down to 80% or even less. Therefore, it’s the system leakage and not the claims by the brand that determine the effectiveness of your purifier. To counter this issue, many manufacturers have started building designs to reduce or eliminate the leakage altogether.

For example, IQAir’s 3D UltraSeal Knife-edge-in-groove sealing between the air purifier’s housing and the frame of the filter ensures maximum efficiency of the filtration system.


Look For Activated Carbon Filter in Your Air Purifier

HEPA or HyperHEPA filters work tremendously in getting rid of airborne particles from the air. But, these are not effective when it comes to removing gases or odors from the air. This is because the molecules comprising gas, odors, etc., are not solid and can easily pass through the densest of HEPA or HyperHEPA filters.

Therefore, you must always look for an activated carbon filter in your air purifier. Carbon filters are designed in such a way that when air filled with gases or odors passes through an activated carbon bed, the gas and odor molecules get adsorbed into the carbon or charcoal pores. This filters gases, odors, and other chemical pollutants, thereby circulating fresh air inside your room.


Look For a Clean Air Delivery Rate (CADR) Rating

CADR or Clean Air Delivery Rate rating calculates the speed at which the air purifier removes dust, smoke, pollen, and other pollutants from the air. You must look for a CADR rating of at least 300 in your air purifier. A rating above 350 is considered excellent.


Pay Attention to the Size Guidelines

A single air purifier can actually treat a surface area ranging from 25 m2 to 120 m2. Therefore, it becomes essential that you pay attention to the size guidelines and choose the purifier of the appropriate size, keeping the dimensions of the area to be treated in mind. If you are looking for optimal air purification. In that case, each room or an enclosed space must have its own purifier so that air circulation stays limited to that area alone. An undersized air purifier or the one that is used in many rooms at a time will be less efficient.


Look For an Association of Home Appliance Manufacturers (AHAM) Verified Mark

AHAM or Association of Home Appliance Manufacturers verified mark ensures the efficiency, safety, and performance of air purifiers. This makes the buying process pretty straightforward by providing a mutual understanding between the manufacturers and the consumers. Therefore, you must always look for an air purifier that is AHAM certified for better and reliable performance.

These are some of the features that you must always look for in your air purifier for the best indoor air purification.


What to Avoid in Your Air Purifier?

What to Avoid in Your Air Purifier

Now that we know what makes a good air purifier, it is equally important that we pay attention to the things that you must avoid in your air purifier. Knowing this will not only cut down the additional costs but will also save you from any health issues arising from such air cleaning technologies. Let’s have a look at them.

Air Ionizers

Ionization technology or Negative ionization is used in many air purifiers to purify the air by releasing anions, having a negative charge to attract positively charged cations found in pollution particles. This technology forces the cations to leave the air and settle on the surfaces like walls, furniture, etc. Though this method can prevent harmful bacteria or molds from spreading in hospitals or dental clinics, it comes with its own set of disadvantages when used in an indoor air purifier for your house.

Firstly, the ionizers do not eliminate pollutants from the air but allow them to settle on the surfaces nearby. This actually increases the pollutant build-up in your room, which can lead to various respiratory and heart conditions. Secondly, these air ionizers can produce ozone, which is extremely harmful in indoor conditions.

Even low levels of indoor ozone can precipitate asthma attacks, irritate your airways, or harm the olfactory bulb. When this indoor ozone builds up to high levels, it can even become fatal. Because of these reasons, we do not recommend opting for an air purifier with ionization technology.


Ozone Generators

It is safe to say that Ozone generators are NOT air purifiers. These are not only ineffective in cleaning the air but are also harmful for you, your children, and even pets. They release ozone molecules into the air through a process known as corona discharge.

The mixing of ozone molecule with that of gas or other particles leads to the process called oxidation. It is this oxidation process that gives the air a distinct smell after lightning or thunderstorm. This is the reason why ozone air purifiers are also marketed with appealing names that suggest thunder, rain, etc.

However, you must not fall for the trap. They don’t even purify the air and come with a whole lot of disadvantages. Firstly, ozone can take many years to clean even a tiny room of gases. Secondly, when ozone reacts with other substances, it can release Ultrafine particles (UFPs) into the air. These UFPs are extremely harmful for your lungs and heart.

Lastly, ozone generators can actually raise indoor ozone levels by up to five to ten times above the safe limits. The recommended range of indoor ozone is 0.05 to 0.1 ppm. But, for those who are easily affected by ozone, like asthma patients, children, pets, etc., even 0.01 ppm of ozone can have life-threatening effects. Therefore, even the safe limits of ozone generators are harmful and must be avoided entirely.


UV Light Purifiers

Though the Ultraviolet or UV purification method is quite helpful in disinfecting medical equipment and preventing the spread of harmful bacteria and viruses, it does not have much to offer when it comes to indoor air purification. In fact, indoor air purifiers are not even that effective in destroying infectious bacteria or viruses. The reason for this is that bacteria and viruses need to be exposed to UV light for a significant period, sometimes up to several hours, before they are seen as harmless.

And, home air purifiers do not expose them to UV light for such an extended period, therefore, becoming futile. Also, UV light is ineffective when it comes to treating harmful contaminants like particulate matter. These can even produce ozone, which is again detrimental for you. And, last but not the least, UV exposure can damage your skin, eyes and even cause cancer.

However, this point is taken care of by many UV air purifier manufacturers as they do not let the UV light shine out of the purifier. But, we still don’t recommend opting for UV light purifiers as these have very little to offer, if at all.


How to Know If Your Air Purifier is Working or Not?

How to Know If Your Air Purifier is Working or Not

Though air purifiers are designed to remove harmful pollutants from the air inside your house and help you breathe clean air, there is still a trust deficit among consumers. And that’s understandable as well. How can we trust an appliance when we can’t even see the pollutants from our naked eye?! How do we know that the air purifier is even working?

Well, you don’t need to worry, as we have discussed a few ways in which you can check if your air purifier is doing its job or not. Though there are other types of air purifiers as well, our primary focus in this section would be the one with HEPA technology. So, let’s get started.

Check Your Air Purifier’s Airflow

The simplest method to check whether your air purifier is working or not is to look at its airflow. As we know that air purifiers draw in air from the room with the help of a fan and blow out clean air after filtration. Now, if you find that the purifier is not blowing out any air even when it is switched on, it is most likely that the device is not working correctly.


Check Your Air Purifier’s Fan

Another way to tell if the air purifier is working correctly or not is by checking its fan. Though the fan pulls and blows out air, its working shouldn’t be very noisy. If the fan makes a lot of noise, there might be an issue with the purifier, or the filter simply needs a replacement. And, if the purifier makes no noise at all, there are chances that it is not pulling in enough air to show any improvement in the indoor air quality.


Check Your Air Purifier’s Filter

As we know, it’s the filter inside the air purifier that traps all sorts of pollutants like pollen, bacteria, mold, etc. Since they do the dirty work, these have to be replaced regularly for the proper functioning of the purifier. Though some air cleaners come with a filter service indicator, we recommend checking your filters manually as well.

This is because filters can be clogged with pollutants, and filter service indicator might not even show that the filter requires service. When this happens, your air purifier itself becomes the source of pollution instead of reducing it. Therefore, you must inspect the air filter regularly by yourself.

Upon inspection, if you find any discoloration or black spots, or the filter looks soiled and dirty, you will know that it needs replacement. The timely replacement of the filter will improve the working of your purifier tremendously.


Use Air Quality Monitor for Your Air Purifier

If you are looking for a universal test that would suit any air purifier type, it is the air quality monitor. This simple monitor provides you with the reading of air quality inside your room. It is a pretty straightforward method.

All you need to do is to test for an initial air quality reading of your room when the air purifier is turned off. Once you have the reading, you must now turn on your purifier. You must ensure that all the windows and doors are closed while the air purifier is on. Now again, take the reading on your air quality monitor. If there has been some improvement, you can rest assured that your air purifier is doing its job well.

It can take anywhere between thirty minutes to a few hours for the air purifier to improve the air quality to healthy levels. In case the purifier has been turned on for a significant amount of time, and there has been no change in the air quality levels, you will now know that your device isn’t working.

Also, if your air purifier is already equipped with an air quality monitor, we recommend not to trust it blindly but rather buy another one. This is because the built-in monitors might have low-quality sensors, resulting in faulty readings. Also, the air near your air purifier is the cleanest, which again leads to inaccurate reading as the actual value will not be reflected on the monitor. Therefore, a trusted air quality monitor is worth the investment.


Where do Air Purifiers Will Not work?

When it comes to improving the air quality inside your house, air purifiers are a worthy investment. But, for them to have a more significant impact, we recommend using them along with a filter. Also, the size of your purifier matters, i.e., if you are looking for cleaner air for your entire house, a larger air purifier will work better than the small portable ones.

Even though air purifiers come with huge potential, they still might be useless if you are not already practicing other methods to get cleaner air inside your home as well. The catch here is that these are pretty effective when it comes to removing the possible allergens or other particles suspended in the air. But, for indoor allergens that are no longer airborne and often rest on the surface of your furniture or carpet, air purifiers have minimal use.


Other Ways to Improve the Air Quality Inside Your House

Indoor air pollution can be a nuisance, not only for those suffering from respiratory issues but also for others. Therefore, the best way to reduce it is to keep your house well ventilated. Also, if you want to take full advantage of your air purifier, you must incorporate these steps as well.

Keep Your House Well Ventilated By Opening the Windows

One of the best ways to keep the irritants at bay is to keep your house well ventilated. When you do this, the allergens or other pollutants don’t get locked inside your room, as proper ventilation is maintained. One quick tip would be to diagonally open your windows as this enhances fresh air inside your room.


Do Not Forget to Vacuum Clean Regularly

As we have discussed above, air purifiers are not very effective when it comes to removing pollutants that settle on the surface. Therefore, it becomes necessary that you vacuum clean your house at least once a week to get rid of these irritants. We recommend going for a vacuum cleaner that is sealed, comes with a bag, and is HEPA-certified. Such a vacuum cleaner will actually help to trap dust particles instead of circulating them back into the air.


RoutinelyChange the Air Filters

We can’t stress enough this point. Routinely changing your air filters makes a whole lot of difference in the quality of air inside your house. The fact is that it is the filter that traps most of the irritants as air passes through it.

This leads to the accumulation of these pollutants inside the filter over time, which reduces its efficiency considerably. As a result, air can’t pass as effectively as before, and the indoor air quality suffers. Therefore, it becomes essential that you regularly change the filters for the air purifier to work optimally.

In case you do not know when to replace your air filter, you can also follow the general filter replacement schedule given below:

  • Carbon Filter: A carbon filter needs to be changed every three to six months for best functioning.
  • Permanent Filter: A permanent filter has to be cleaned every three months and changed when they are damaged.
  • HEPA Filter: HEPA filters usually last long. But, you must replace these every twelve to eighteen months.
  • Pre Filter: A pre-filter should be cleaned once every thirty days and replaced when it is visibly worn out.

However, you must keep in mind that these are general guidelines, which will be valid for most air purifiers, yet there can be some exceptions. In case there is any specific schedule, it will most likely be mentioned on the brand’s website or the user manual.


Use a Kitchen Chimney or an Exhaust Fan in Your Kitchen

When you cook, all kinds of smoke and odors are filled in your kitchen. These are some of the most significant contributors to indoor air pollutants. Therefore, we recommend using a kitchen chimney, if you have one, or an exhaust fan to expel these out to the outside environment. And, remember not to use them while cooking but after it. A ducted chimney would be a preferred choice.


Reduce the Usage of Candles

Though the burning of candles adds to the warmth inside your room, these can also be one of the most significant reasons for indoor air pollution. Candles on burning release particulate matter or candle soot into the air. Most paraffin-based candles emit carcinogenic pollutants like benzene, toluene, etc., that can not only cause cancer but are also linked with birth defects and asthma.

No, you don’t have to stop burning candles altogether. You can go for safer options instead. For example, you can go the traditional way by opting for beeswax or soy candle. Essential oils also work well in offering you that luxurious experience. Or, flameless candles can provide you with the same relaxing experience without the harmful pollutants of a petroleum candle. In case you can’t opt for these options, you can just reduce the time or frequency of burning candles at your place.


Do Not Smoke Inside the House

We know that smoking is injurious to health. But, how many of us know that smoking inside the house can make the indoor air far worse than outdoor pollution. Second-hand tobacco smoke is a significant contributor to indoor air pollution. It puts the person at risk of developing asthma or other respiratory illnesses. Therefore, it becomes necessary that smoking inside the house be banned. This small change can help reduce pollutant sources, which in turn results in improved indoor air quality.


The Bottom Line – Are Air Purifiers Really Effective?

Do air purifiers work? The short answer would be Yes. These are especially a good option for those suffering from respiratory issues, allergies, etc. But are they really effective? This is entirely subjective and depends on a number of factors like the level of indoor pollution, the quality of the air purifier, what else do you do to control indoor pollution, etc.

Also, air purifiers don’t work on all pollutants. These are pretty ineffective in treating surface contaminants. And, other types of air purifiers, like ionizers, ozone generators, etc., are even more harmful than certain pollutants themselves because of the ozone that they generate as the by-product. Still, an airtight air purifier with a True HEPA filter and a carbon filter is an efficient option for your house.

Which air purifier did you choose? Was it helpful for you? Please share your experience with us in the comments section below. If any doubt regarding air cleaners still prevails, you can reach out to us. We shall get back to you as soon as possible.

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