UV is a form of radiation which is invisible to the human eye.
UV radiation is only one form of radiation and it is measured on a scale called the electromagnetic spectrum.
Radio waves, microwaves, visible light and X-rays are all forms of EM energy.
UV radiation is the portion of the EM spectrum between X-rays and visible light.

The most common form of UV radiation is sunlight, which produces three main types of UV rays:

UV-A, UV-B & UV-C
UV-A rays have the longest wavelengths, followed by UV-B, and UV-C rays which have the shortest wavelengths.
While UV-A and UV-B rays are transmitted through the atmosphere, all UV-C and some UV-B rays are absorbed by the Earth’s ozone layer.

So, most of the UV rays you come in contact with are UV-A with a small amount of UV-B. Like all forms of light on the EM spectrum.
UV radiation is classified by wavelength. Wavelength describes the distance between the peaks in a series of waves. UV-B rays have a short wavelength that reaches the outer layer of your skin (the epidermis) UV-A rays have a longer wavelength that can penetrate the middle layer of your skin (the dermis) UV-C radiation has the shortest of the three and is the highest energy portion of the UV radiation spectrum.
UV-C radiation from the sun does not reach the earth’s surface because it is blocked by the ozone layer in the atmosphere. Thus, the only way that humans can be exposed to UV-C radiation is from an artificial source like a germicidal lamp.

Over 100 years ago it was discovered that Ultraviolet light, when used properly, has germicidal properties and can destroy microorganisms.

Now ultraviolet (UV-C) light is commonly used for disinfection. It inactivates microorganisms (including viruses) by breaking down the genetic material and structural molecules so that they are no longer infectious. UV-C irradiation is commonly used to disinfect water, air, and surfaces.

While common in the medical and industrial community, because the wavelengths that are most effective at inactivating pathogens are also considered damaging to human skin and eyes, it has not taken the forefront as a disinfectant by the general public due to the concerns that it can cause harm if is not properly used. Rest assured we have taken every precaution to ensure that our unit is perfectly safe as detailed below.

An interesting article can be found here for a deeper dive into the evolution of UV in its various uses.

The Uvanna UV Air Sanitizer was designed with safety in mind

It is perfectly safe to operate in occupied spaces

The Air chamber protects from UV-C radiation harming
•Eyes & Skin
•Pets & Plants

No harmful ozone emission
•Special lamp glass filters out the 185 nm ozone-forming radiation

Automatic shutoff function turns off the indicator light and fan if the UV-C bulb is not functioning correctly

ETL Certified to UL 507 Standard