In this post, we’re going to explain everything you need to know about UV lights and air purifiers.

In particular, you’ll learn what does the UV light do on an air purifier, how does a UV air purifier work, when should you use a UV light on an air purifier, do UV lights improve air quality, and are UV light air purifiers safe to be around.

By the end, you’ll be as close to an expert as you can on the topic of ultraviolet light and air purification so you can decide if you want to use this technology in your home or not.

What Does the UV Light Do on an Air Purifier

What Does the UV Light Do on an Air Purifier?

The UV light on an air purifier uses the UV-C spectrum of ultraviolet light to inactivate airborne pathogens and microorganisms like mold, bacteria, and viruses. The purpose of the UV mode on an air purifier is to sterilize indoor air.

Air cleaners that use ultraviolet light to kill microorganisms are also known as “UVGI air purifiers” and “UV-C air purifiers”. UVGI stands for ultraviolet germicidal irradiation and UV-C is a spectrum of ultraviolet light, which we’ll explain next.

The reason why UV lights on air purifiers are so effective against microorganisms and pathogens is that ultraviolet light exposure damages their DNA and RNA structure so reproduction cannot occur. For example, bacteria have a single cell, and it relies on their DNA to survive. Therefore, when bacteria come into contact with a UV light on an air purifier, the bacterial cell’s DNA gets sufficiently damaged, and that triggers a self-destruct mechanism, which renders it harmless.

Viruses, on the other hand, are not made out of cells but rather a set of genes bundled within a protective protein shell called a “capsid”. And according to the U.S. Food and Drug Administration, “UVC radiation has been shown to destroy the outer protein coating of [viruses]” as a way to inactive them.

For that reason, we recommend air cleaners with UV lights on our best air purifier for viruses reviews because they’re the most effective technology for this purpose.

Types of Ultraviolet Light

When we’re explaining the concept behind what is UV mode on an air purifier, we’re talking about a spectrum of light called “UV-C light”.

Ultraviolet is split into three sections:

  • UV-A light: 315–400 nanometers with photons that vibrate just a little faster than visible light. UV-A light accounts for 95% of the sun’s radiation that reaches the earth. It is commonly used in tanning beds.
  • UV-B light: 280–315 nanometers with photons that vibrate even faster. UV-B light causes most sunburns. It affects the top layer of your skin and damages DNA.
  • UV-C light: 100–280 nanometers with photos that vibrate the fastest and carry the most energy. UV-C light is the most dangerous to living organisms and cells. The earth’s atmosphere blocks 100% of UV-C radiation from the sun.

What’s nice about UV-C light is that it can be artificially made and harnessed to improve air purifier effectiveness.

In fact, UV light is an established method of disinfecting scientific and medical equipment as well as entire rooms where sanitation is crucial. According to a study by Duke Health researchers “UV-C is helping hospitals cut transmission of superbugs like MRSA that linger in patient rooms and cause new infections. As a result, several UVC machines are now in use at Duke University Hospital, Duke Regional Hospital, and Duke Raleigh Hospital.”

How Does a UV Air Purifier Work?

How does a UV air purifier work

A UV air purifier works by pulling air into the unit and passing it through a filter, such as a HEPA filter. The air then passes through an internal chamber where it is exposed to UV-C light. The UV air purifier works here to inactivate microorganisms and pathogens.

UV-C lights are silent and invisible to the human eye. However, some air purifier manufacturers put a color filter over the lamp so that it produces a blue glow. This is more for aesthetics than any practical purpose.

UV light bulbs also must be replaced after a certain amount of time. Most UV lamps are rated at 10,000 hours, or slightly longer than one year when operated for 24 hours per day.

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When Should I Use UV Light on an Air Purifier?

You should use a UV light on an air purifier when you want to destroy airborne microorganisms and pathogens. By using the UV light on an air purifier, you can lower the number of bacteria, viruses, and mold spores inside a room.

Therefore, it’s best to use the UV mode on an air purifier as much as you can. As the air gets pulled into the system, more and more biological aerosols will get destroyed. Over time, you can effectively sterlize the entire air inside a room when using the UV light mode.

Do UV Lights Improve Air Quality?

UV lights do improve air quality because they are a sanitation device. A UV light can inactivate biological aerosols that affect indoor air quality, including mold, mildew, fungus, bacteria, and viruses. Therefore, having an ultraviolet light mode on an air purifier can improve the air purification quality of the unit.

The main purpose of a UV light on an air purifier is to reduce your exposure to harmful microorganisms and pathogens. So any improvement that can be made by removing those elements from indoor air will improve the overall quality of it.

Essentially, a UV light picks up where all other types of air purification technologies fail. The two most common types include HEPA filters and ionizers.

We have dedicated articles on the topics of what do HEPA filters do and how do ionizers work, but the basic idea is that both HEPA filters and ionizers are good for removing airborne particles like dust, allergens, smoke, and pet dander. However, neither of those things can destroy bacteria, viruses, mold, or fungi as we discuss in our air purifier vs ionizer guide.

Therefore, it’s best to buy an air purifier that includes a HEPA air filter or ionizer along with an ultraviolet light for maximum air quality protection.

Are UV Air Purifiers Safe?

UV air purifiers are generally safe for indoor environments. The UV-C light is enclosed inside the unit, so there is no direct exposure to the lamp to harm human health. However, some UV lights can produce ozone as a byproduct if it’s not using a wavelength of 160-240nm.

A potentially dangerous component of UV lights in air purifiers is the production of hazardous ozone. Ozone is an unstable oxygen molecule (O3) that reacts to other molecules it comes into contact with. While ozone is a good air sterilizer and odor neutralizer (we even have a page that offers the best ozone machine reviews), the effects on human health can be serious by impacting lung functions.

However, not all UV light air purifiers are dangerous. Ozone production often occurs when the UV-C lamps are uncoated. Because of this, some air purifier manufacturers use a special coating on the UV lamps so they don’t react with oxygen molecules to cause harmful ozone as a byproduct.

According to Energy Vanguard, “Not all UV lamps result in ozone generation, however. The key is the glass used in the lamp. Soft glass or regular quartz glass allow the 185 nm UV-C to pass through and generate ozone. But when quartz glass doped with titanium is used, all of the 185 nm UV-C is absorbed.”

Are UV Air Purifiers Worth it?

UV air purifiers are worth it. Research shows that UV lights inactivated 75% of fungal spores and 97% of bacteria cells captured in the air filter medium within 60 minutes. A UV air purifier can be effective against viruses, bacteria, mold, and fungi by breaking down their DNA or RNA.

Additionally, a study reported by Infection Control Today revealed, “After exposing eight common non-critical patient care items to two 30-second UV-C irradiation cycles, bacterial numbers on 40 of 51 target  sites were consistently reduced to below detectable levels.”

So if you were wondering, “do you need an air purifier?”, then the answer is yes if you want overall better air quality that has less harmful particles in it.

If you want to find a good air purifier for your needs, then take a look at our top 10 air purifiers guide. Some of these units include a high-quality UV light for sterilizing indoor air.

We also have a page on the best affordable air purifiers here if you’re looking for a low-cost option.

What Does the UV Light Do on an Air Purifier Summary

We hope you enjoyed this guide that answered the question, “What does the UV light do on an air purifier?”

As you discovered, UV lights are a powerful air purification technology that can sterilize indoor air. The basic idea behind how does a UV air purifier work is that it disrupts the DNA and RNA structure of microorganisms and pathogens in order to render them harmless.

Air purifiers with UV lights are a good way to improve air quality for anyone who wants fewer bacteria, viruses, and fungi floating around in their home.

Now you know what is UV mode on an air purifier and when to use it.

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About David Morrison

David is an Air Quality & Comfort Technician. He has expert knowledge on the technology and design of air purification, air conditioning, and heating systems. His main role is to write content that helps people get the most value out of their air purifiers, air conditioners, and heating units. (See Full Bio)