How UV-C Works

Types of Ultraviolet Light

UV-A, UV-B, and UV-C are part of the ultraviolet spectrum and we are exposed to some of each type of UV light every day. UV-A is also known as "blacklight" and is generally harmless. It results in skin tanning and is used in medicine to treat certain skin disorders. UV-B has a very high penetrating ability and prolonged exposure is responsible for some types of skin cancer, skin aging, and cataracts (clouding of the lens of the eye).

UV-C, also known as ultraviolet germicidal irradiation (UVGI), has extremely low penetrating ability and is nearly completely absorbed by the outer, dead layer of skin where it does little harm. It does reach the most superficial layer of the eye where overexposure can cause redddening and painful but temporary irritation, but it cannot penetrate to the lens of the eye and cannot cause cataracts.

Why Germicidal UV Is Effective

Germicidal UV has a specific wavelength of 253.7 nanometers (billionths of a meter) and is known to deactivate (break the DNA of) microorganisms contained in tiny airborne droplets (droplet nuclei) that transmit diseases such as measles, tuberculosis, and influenza from person to person. Once the DNA of a microbe is broken it loses its ability to reproduce. Bacteria and viruses that can not reproduce are rendered harmless. Germicidal UV has been used safely and effectively in hospitals, clinics, laboratories, and industry for more than 50 years.