UV light and disinfection

The basics of UV light

Often referred to as ultraviolet (UV) light, UV radiation is a type of electromagnetic radiation with wavelengths shorter than visible light and longer than X-rays.

UV radiation falls into three main categories depending on its wavelength: UVA, UVB, and UV (see the diagram below). The shorter the wavelength, the more energetic the radiation. UV, which has the shortest wavelength, can act as a disinfectant and has been used in healthcare, food, and biotech for over 30 years.

UV light works as a disinfectant because direct exposure to UV light ruptures the DNA or RNA of bacteria, viruses, and other germs, making them unable to multiply and cause an infection.

How UV disinfection works

UV light initiates a reaction between two molecules of thymine, one of the bases that make up DNA (in RNA, thymine is replaced with uracil). If the damage is extensive, the DNA/RNA sequence is altered, which prevents the pathogen from reproducing. Thymine and uracil are especially sensitive at wavelengths at or near 265 nm.

What is particularly interesting is that polychromatic light, which means light with a broader UV spectrum, is more effective at inactivating certain pathogens than light sources that emit monochromatic light at 265 nm. A broader spectrum means that the light damages other cellular and viral components than nucleic acids inducing even more significant damage to the pathogen and preventing regrowth.

Several studies have investigated this subject, and researchers have found that UV light at a broad range of wavelengths hinders subsequent photoreactivation (1).

(1) For example, Oguma K, Katayama H, Ohgaki S. Photoreactivation of Escherichia coli after low- or medium-pressure UV disinfection determined by an endonuclease-sensitive site assay. Appl Environ Microbiol. 2002;68(12):6029-6035.

Disinfection vs. sterilization

The PureFize^® technology is designed for disinfection. Understanding the difference between disinfection and sterilization is essential, as these terms are often misused.

Disinfection and sterilization are both decontamination processes. Sterilization is a process that destroys or eliminates all forms of microbial life and is carried out in medical and healthcare facilities. It is usually done through combinations of heat, irradiation, filtration, high pressure, etc. A product that has been sterilized is safe for use in an operating procedure or as an implant.

Disinfection describes a process that eliminates almost all harmful microorganisms. The level of disinfection is described using a standard called logarithmic (log) reduction. When evaluating products for high-level disinfection, their log reduction capability is paramount.

PureFize has been shown to provide extremely high germicidal reduction quickly. Up to log8 microbial inactivations have been proven, which puts the PureFize technology as close to sterilization as possible.

Ensuring proper disinfection

The effectiveness of UV disinfection depends on several factors, such as the power of the UV source, type of UV spectrum, exposure time, the distance of micro­organisms from the light source, type of microorganism, the presence of particulate, shadow zones, etc.