What difference does UV light make in an air purifier?

We have heard of air purifiers using True HEPA filters and activated carbon filters to purify the air in our homes. But did you know that other technologies are also used in air purifiers? That’s right. One particular element is UV Light. Air purifiers using UV Light only are known to purify the air by targeting mold spores and mildew quickly. This has given rise to a few doubts regarding the safety of using UV Light.

Here, we will discuss the effect of UV Light in air purifiers, especially if you are living in an area that brings mold and mildew into your homes.  

How do UV air purifiers clean the air?

Air Purifier With UV

More often than not, when we think of air purification, we instantly think of True HEPA air filters. HEPA air filters are considered to be of the highest standard and deliver the results we are looking for every time.

However, other technologies have recently come into use that has proven useful, such as UV light. Air purifiers with UV Light are great as disinfection tools. When combined with a true HEPA filter, UV air purifiers deliver fantastic results.

To truly understand what UV light air purifiers are, it is best to start with the ABCs of UV light. UV light or ultraviolet light is a kind of electromagnetic radiation. It rests outside the spectrum for human beings. Its wavelength is shorter than the visible spectrum, although it is longer than that found in X-rays. UV light makes up around 10% of sunlight.

While it can cause you to develop sunburns, its cell-destroying properties make it useful to remove air impurities. Naturally occurring ultraviolet light occurs in three forms – UV-A, UV-B, and UV-C.


UV-A is the most common type of UV light that accounts for 95% of the sun’s radiation that reaches the earth’s surface. Tanning beds use UV-A light. Unfortunately, it also causes the skin to wrinkle and age prematurely.


UV-B causes the biggest concern to humans. Most sunburns are caused by UV-B light, which affects the top layer of your skin and damages DNA with prolonged exposure.


UV-C is considered the most harmful and most dangerous to living organisms and cells. Fortunately, the earth’s atmosphere can block 100% of UV-C radiation.

With the advancement in technology, we can make artificial UV-C. If used properly, the harmful effects of UV-C light can be used to purify the air. Therefore, what is harmful in UV-C light can help purify the air.

Air purifiers typically use UV-C light (or short-wave ultraviolet light) to inactivate airborne pathogens like bacteria, mold, and viruses. Their primary purpose is to reduce indoor air pollutants. UV germicidal irradiation or UVGI air purifiers is another term for this type of technology.

UV air purifiers use UV lamps that alter the DNA of microorganisms present in the air, thereby making them inactive and eventually destroying them. The air from the room is pulled into the unit and passes through the HEPA filter. Then, the air moves into a small internal chamber where it is exposed to UV light. The UV light is kept contained within the air purifier as it can be harmful to look at directly. The UV-C light does not get released into the room, preventing direct exposure.

The type of model determines whether or not the air will be passed through yet another filter before releasing fresh air back into the room.

When Should You Use UV Light on an Air Purifier?

If you have concerns about exposure to UV light and, as a result, are unsure when you need to activate the UV function on your air purifier – don’t be. You can control the use of UV light in your air purifier.

For ideal results, make sure you leave the air purifier with UV light on all the time. For thorough sterilization to take place, you will need to allow the air purifier to run most of the time, if not all the time. Here are your options on when it’s best to run the UV light:

  • Run it overnight
  • Run it when you are not at home
  • Run it 24/7, too – it’s perfectly safe!

Which is better HEPA or UV light?

Choosing which type of air purifier to pick is always hard, especially if you have too many choices. Therefore, we have listed all the pros and cons of both types of air purifiers to help you decide on the type that is most suitable for you and your household needs. 

Pros of HEPA filters:

  • HEPA filters can trap a large concentration of air pollutants in one cycle. 
  • HEPA filtration systems combine other air purification methods (including UV-C light) to provide a more thorough air filtration process.
  • They are highly affordable with quality technology.
  • HEPA filters don’t produce harmful byproducts
  • True HEPA filters are ideal for those who suffer from allergies and other respiratory problems.

Cons of HEPA filters:

  • HEPA filters do come with the disadvantage of reintroducing the trapped microorganism back into the air. You can prevent this by conducting regular maintenance checks and frequent filter changes, which could be expensive.
  • HEPA filters are not always as effective against smaller air pollutants

Pros of UV Light Air Purifiers

  • UV-C air purifiers are far more technologically advanced, offering a superior sanitization process. 
  • UV light eradicates viruses and bacteria as small as 0.1 microns, including the SARS-CoV-2 mutation capable of passing through the HEPA filter. 
  • They also use less energy than the HEPA air purifier, which requires a constant level of airflow to run. 
  • The UV light bulbs are long-lasting and do not need to be replaced frequently.

Cons of UV Light Air Purifiers

  • Most UV-C air purifiers come as standalone units or part of a bigger filtration system. 
  • Standalone UV-C air purifier costs a lot more than HEPA air purifiers. 
  • UV Light air purifiers are not effective against every type of air pollutants
  • If not appropriately coated with the correct material, the UV lamp built into the UV light air purifier could release ozone as a byproduct into the atmosphere. Ozone generation is known to be harmful to humans.

Now that you have all the pros and cons of HEPA air purifiers and UV light air purifiers, you can make the right choice for your home and family. But, be it for your home or for commercial use, a UV-C filter that’s part of a larger filtration system would be safest, i.e., combining both HEPA filter and UV-C light technology. Such systems make an overall impact on air contaminants. 

What is the healthiest air purifier?

The market offers many types of UV air purifiers targeting different audiences. While some models focus on the power of germicidal irradiation, others offer unbeatable prices that are hard to match. And because UV-light does not fall under AHAM testing, some manufacturers exaggerate the performance output of their models to boost sales. Fortunately, you can bypass all the ineffective and dubious UV air purifiers with uncoated UV lamps, with our recommendation on the healthiest air purifier. Air purifiers that use a combination of True HEPA filters and UV-C Light are considered safe and fit for homes. Some of our top picks include

  1. GermGuardian True HEPA Air Purifier With UV Sanitizer
  2. Pure Enrichment Pure Zone Air Purifier
  3. TruSens Air Purifier with UV-C Light + HEPA Filtration 

FAQ Section

1. What are the types of Ultraviolet Light?

There are three types of Ultraviolet Light:

UV-A light
  • UV-A light of 315-400 nanometers with photons that vibrate a little faster than visible light. UV-A light constitutes 95% of the sun’s radiation that reaches the earth. Tanning beds make use of this kind of Ultraviolet light.
UV-B light
  • UV-B light of 280-315 nanometers with photons that vibrate even faster than UV-A light. Most sunburns are caused by UV-B light, affecting the top layer of our skin. UV-B is also responsible for DNA damage.
UV-C light
  • UV-C light of 100 – 280 nanometers with photons that vibrate the fastest compared to UV-A and UV-B light. They carry the most energy. UV-C light is considered the most dangerous to living things. The earth’s atmosphere is responsible for blocking off 100% of UV-C radiation from the sun.

2. Do UV air purifiers work on viruses?

The primary use of UV light air purifiers is to remove harmful pathogens from the atmosphere. Not only does the UV light capture bacteria and viruses from the air, but they also destroy and kill them, making them an excellent disinfectant and germicide tool. Recent studies show that UV light can be used to disinfect and kill airborne COVID-19 particles. And, that SARS-CoV-2 is highly susceptible to irradiation with ultraviolet light. That said, UV rays alone cannot prevent the occurrence of COVID-19. 

3. Do you need UV light with a HEPA filter?

Many HEPA air purifiers combine other air purifying methods like UV light to provide a robust air filtration process. The HEPA filter is great for preventing allergies, odor issues, respiratory problems, and general air cleaning. At the same time, the inbuilt UV light function will target the removal of harmful pathogens like viruses and bacteria from the air, making the model an excellent disinfectant tool. A standalone UV light air purifier will turn out to be an expensive proposition, thanks to the relatively new technology it comes with. Therefore an ideal choice will be to choose an air purifier that comes with a HEPA filter and an inbuilt UV light function.

4. Do UV lights in air purifiers create ozone?

Most UV air purifiers are generally considered safe for indoor use. The UV-C light is well encapsulated inside the purifying unit, thereby preventing direct exposure to the UV lamp that could prove harmful to human health. That said, some UV light could produce ozone as a byproduct if it does not use a wavelength of 160-240 nanometers.

Ozone is an unstable form of the Oxygen molecule that reacts with other molecules when contact is made. Ozone production by a UV air purifier usually occurs only when the UV-C lamps are uncoated. As a result, some manufacturers use a special type of coating on the UV lamps to prevent a reaction with oxygen molecules that produce ozone as a harmful byproduct.

Wrapping Up

Hopefully, this article has armed you with enough information about UV light air purifiers and how they work. UV light air purifiers are great disinfectant tools that deliver an extremely holistic air purification process when used together with a HEPA filter. They work by drawing in air that will eventually pass through a chamber fitted with a UV lamp. The UV lamp is responsible for killing and destroying the DNA of harmful pathogens found in the atmosphere.

We have also highlighted the safest and most appropriate times at which you can choose to turn on the UV mode on your air purifier, should you be worried about Ozone emission. Overall, they are sound air purification systems useful for anyone who wants to reduce, if not get rid of, all the bacteria, viruses, and fungi floating around their homes. 


About The Author

Olivia — a self-confessed air quality addict — is a home climate enthusiast, fresh air advocate, and someone with deep personal experience and knowledge about mold extermination. Her work was mentioned in countless notable humidity publications. Previously she was an editor at Mold Remediation.