Although HEPA filters are the primary filtration method for portable air purifiers, other technologies can be used to clean the air, too. One of these is based on ultraviolet light, or UV light for short. More specifically, some modern air purification systems use UV-C (ultraviolet-C) light as part of their clean air tech.

But how does a UVC light air purifier work, and more importantly, is it safe? In this guide, we look at the UV air purifying method and whether you should consider adding this technology to your home or office.

What is UV Light?

First, we need to explain what ultraviolet light is. In short, it’s a form of electromagnetic radiation that exists just outside the visible light spectrum, meaning it is not visible to the naked eye. It makes up roughly 10 percent of the sun’s output, and the wavelengths are shorter than visible light but longer than X-rays. Although you can’t see UV light, you can certainly feel its effects in the forms like a sunburn after a day on the beach.

As opposed to sunburned skin, there are benefits when we harness the power of UV light. Both natural and artificial UV light waves are used in different products such as black lights, plant grow lights, tanning beds and arc welders. UV light has been used for many years to disinfect wastewater, equipment and even foods and beverages. In air purification, UV light can reduce bacteria, viruses, mold and other airborne contaminants. 

Types of UV Light

There are three subtypes of ultraviolet light that work in different ways. Let’s take a quick look at each of them.

1. 1. UV-A Light: Light with 315-400 nanometer (nm) wavelengths and photons that vibrate slightly faster than visible light. This “black light” makes up of the sun’s radiation on earth and is primarily used in tanning beds. Although it has the least energy among UV rays, excessive exposure can cause skin wrinkles and cause you to age prematurely.
   2. UV-B Light: This light has wavelengths of 280-315nm and even faster photon vibrations. UVB has slightly more energy than UVA rays and It’s what causes most sunburns of any UV light, and it has been linked to skin cancer and even DNA damage.
   3. UV-C Light: These 100-280nm light wavelengths vibrate the fastest and carry the most energy. It is the most harmful UV light; however, the earth’s atmosphere blocks 100 percent of the sun’s UV-C radiation.

How does UV light reduce bacteria?

A UV air purifier utilizes UVC light to destroy the DNA in bacteria, viruses, fungi, and other microorganisms. The same properties that make it potentially harmful also make it great for air purification. A UVC air purifier damages the DNA in microorganisms surrounding the UV lamp inside the purifier. Since microorganisms typically only consist of one or a few cells, sufficiently damaging the DNA is enough to sterilize them. This prevents new spores from multiplying, therefore rendering them harmless. Furthermore, the UV-C light is contained within the air purifier, so humans aren’t exposed to it.

How long does it take for UVC to destroy the bacteria cells?

The best UVC air purifier system can remove contaminants in seconds. Many variables go into this, including how intense the light is, how long microorganisms are exposed, and how far they are from the lamp. A 30-watt lamp will cover about 200 square feet when used over a long period of time, and the closer bacterium get, the faster the UVC light destroys the cells.

Different Types of UV Germicidal Lamps

There are four germicidal lamp designs for various situations:

1. 1. Low-pressure mercury-vapor lamps are similar to fluorescent lamps with a fused quartz tube and no phosphor, which allows UV-C light to leave it unaltered. This is a more common type.
   2. High-pressure mercury lamps are closer to HID lamps with intense broadband UVC radiation, which is effective for industrial water treatment.
   3. Excimer lamps emit narrow-band UVC and vacuum-UV radiation at varying wavelengths, reaching full output quicker and with less heat than a mercury lamp.
   4. Light-emitting diodes, or LEDs, use semiconductor materials to emit tune-able wavelengths in a smaller size.

Low-pressure mercury and LED are the most common UV germicidal lamp types used for air purifiers. While LEDs can emit UVC, they are very inefficient, and are typically much less powerful compared to other lamps. Disinfection requires high energy and time, so for LEDs to work, the bacteria would have to be exposed to the LED for a lengthy amount of time (much longer than it would take to flow in and out of an air purifier) and be very close to the LED. The SKYE air purifier uses Low-pressure mercury lamps to ensure a high level of effectiveness.

Benefits of UV Portable Air Purifiers

A UV portable air purifier has many advantages for home air purification. These purifiers are excellent at quietly reducing bacteria, viruses and germs from the air. This makes them a great choice for people with weakened immune systems, along with protecting us all from invisible germs floating through the air. A HEPA filter will, at best, contain these micro-organisms — and many are too small for HEPA filters to even do that. UVC air purifiers also are effective on mold spores, fungi and odors, and they’re easy to maintain. All you need to do is change the UV bulb once a year for maximum effectiveness.

Potential Drawbacks of an Air Purifier with UVC Light

Despite the many pros of germicidal UV air purifiers, it’s important to remember there are a few cons. The technology won’t remove the solid airborne particles like those a HEPA filter targets, such as dust, pollen, and pet dander. UVC light also isn’t effective against VOCs, gases or chemical fumes. In older or cheaper purifiers, there is also a risk that small amounts of ozone will leak into the surrounding air, which is harmful to humans. Be sure to look for California Air Resource Board CARB certification, which certifies the units to be ozone free.

Why UVC Air Disinfection Technology is Worth the Investment

When used as instructed and with proper exposure, ultraviolet-C light is an effective and safe way to filter the air in your home. A portable air purifier equipped with UVC light is most effective in tandem with a HEPA filter, carbon filter, and PCO technology for a full spectrum of protection for the freshest and safest air possible. The SKYE Portable Air Purifier utilizes all of these cutting-edge technologies to help clean your home’s air for the cleanest and freshest air.