How Do UVC Air Purifiers Work

UV light devices are becoming popular because of the current virus situation in the world, and this is reflected also in air purification technology development. So how do UVC air purifiers work really? Keep reading, the answer is given in the text below.

Explaining terminology

You have seen the letters UVC in the title, sometimes this is written as UV-C, both notations mean the same. This abbreviation is used to describe the C range in the ultra-violet part of the spectrum. You do not need to be a physicist by profession to understand this (by the way I am a theoretical physicist), but this is all about light wavelengths that are not visible by human eyes.

The light spectrum is continuous, but it seems that some find it convenient to divide it into UV-A, UV-B, and UV-C wavelength ranges. You can see them in the graph below. The UV-C range is important for this text about air purification.

This UVC radiation is normally absorbed by the atmosphere and we do not have much contact with it. Luckily, I would say because UV radiation is really dangerous for humans and it can damage your eyes and fry the skin within minutes.

UV light range and its UVC part that kills microbes.
UV light range and its UVC part that kills microbes.

Surprisingly, I have seen a statement in one site that this UVC range is “harmless for people”, nothing can be farther from the truth. Never expose any part of your body to this radiation.

But did you ever think about why we see what we describe as the ‘visible light‘? This is just a relatively narrow range in the electromagnetic waves spectrum, so what makes it special?

Well, the answer is more or less this – we are the children of our nearest star, the Sun, and this star radiates maximum of its energy in the wave-range which we describe as the ‘visible light’. So there is no visible light for itself, it is just about the evolution of humans. We have developed receptors for the Sun’s radiation corresponding to this wave range.

But why? Because this is the range where there is a maximum of energy emitted by the Sun, so this was the easiest way to evolve and develop receptors (our eyes). Isn’t this incredible?


Does UVC light kill germs?

The term germ is frequently used instead of the original word pathogen that comes from the Greek language, but the meaning is the same. It includes viruses, bacteria, protozoa, and a few more micro-organisms that generally cause diseases. I shall here focus mainly on viruses and bacteria.

So does ultraviolet light kill bacteria?

The short answer is yes, this has been known for longer than a century and used for the first time in 1910 to disinfect water in Marseille in France. More on this you will find in Wikipedia.

Does UV light kill viruses?

Again, the short answer is yes. There are scientific studies related to this. To be specific, UVC light affects their DNA, so it is not exactly that it kills microbes, but it prevents microbes from replicating and it makes them harmless. There is more on this topic in my separate text on how an air humidifier can protect you from viruses.

if you have time, I would warmly suggest you to see this video, this is a scientific lecture, it is a bit long but very instructive:


Back to the topic – what is a UV light air purifier?

So here you can have at least the following different types:

  • A UV light air purifier where the water is exposed to the UVC light and then such a clean water vapor is dispersed into the air.
  • A UV light air purifier where the air is exposed to the UVC light. This can be within an air purifier (some of them shown below), or this can be just a UVC lamp in the room. In view of what is mentioned above, such lamps must be used with great care and I would not recommend them for home use. This is why I shall not discuss them here.

In any case, the main purpose of the UVC light source is to sterilize eventual microbes present in the mater (vapor or air) that leaves the purifier, or to sterilize them directly in the room air.

Examples of UV light air purifiers

• One excellent example of an air purifier with water treated by the UVC light is this Honeywell HCM350B Germ-Free Cool Mist Humidifier. So water coming from its tank is exposed to the UVC light and this sterilizes it completely. After that, the clean vapor created from this water spreads through the room air.

Honeywell HCM350B Germ Free Cool Mist Humidifier
Honeywell HCM350B Germ Free Cool Mist Humidifier.

• This Germ Guardian Desk and Office Air Purifier is an example of an air purifier where the air is exposed to the UVC light and in passing through the device it becomes sterilized.

Germ Guardian Desk and Office Air Purifier.
Germ Guardian Desk and Office Air Purifier.

The picture below shows all the functions included in this excellent device:

• Yet another example of the technology where air is treated by the UVC light when it passes through an air purifier, is this Germ Guardian Air Purifier True HEPA Filter.

Germ Guardian Air Purifier True HEPA Filter.
Germ Guardian Air Purifier True HEPA Filter.

As you realize, this is the product from the same brand as the previous purifier, so all the functions presented in the previous picture apply here as well. So you have 4 levels of air purifications:

  1. Pre-filter that removes larger particles.
  2. Activated carbon filter that is included to remove odors and some chemicals in the air.
  3. True HEPA filter. If you are not familiar with this terminology, the meaning is high-efficiency particulate absorbing.
  4. UVC air purification.

It is important to stress here that in all these devices shown above the UVC light unit is stored inside of the device, so it is safe to use them. Under no circumstances, you should ever watch into these UVC units directly. Make sure also that kids have no access to it.


In summary, I hope this text has been helpful and you have some better idea of what a UV light air purifier is and how such devices work. Check our separate text with best air purifiers with UV light.

Please let me know if you have any question, there is a comment box below. Bookmark this site and stay informed, we add texts here regularly.

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