Technology

The science. Explained.

What is UV-C? -How does it kill bacteria & viruses?

Ultraviolet (UV) light is produced naturally by the sun. Ultraviolet is a spectrum of light just below the visible range and it is split into four distinct spectral areas, of which UV-C is one.

The UV-C Spectrum

The entire UV spectrum can to some extent kill or inactivate microorganism species like bacteria, viruses, spores and protozoans. It does this by preventing them from replicating; unable to produce offspring the colony dies and the surface is disinfected, but the most effective, UV light – UV-C, does not naturally reach the Earth’s surface as it is filtered out by the Ozone layer, protecting the natural world from its powerful and dangerous radiation.
High-intensity UV-C light, generated by special fluorescent tubes at a wavelength of 253.7 (often abbreviated to 254) nanometres provides a germicidal effect many thousands of times greater than UV in nature; this is the technology used in Uvisan products. The application of UV-C energy to inactivate microorganisms is also known as Germicidal Irradiation or UVGI and it is one of the most effective and rapid antimicrobial methods available to science and has been used for many years in such applications as the disinfection of water.

How UV-C kills bacteria & viruses

UV-C exposure inactivates microbial organisms such as bacteria and viruses by destroying their DNA, the ‘blueprint’ these organisms use to develop, function and reproduce.
By removing the organism’s ability to reproduce, it is rendered harmless. After UV-C exposure, each individual organism is incapable of creating more organisms and itself dies off, and with no offspring the entire population of microorganisms dies too. So effective is UV-C in disabling microorganism that in University laboratory tests using live bacterial on Petri dishes and conducted using Uvisan cabinets, zero colony growth was recorded in the middle section of the cabinet shelves and at least 99.99% colony reduction was observed at the outer edges.

Uvisan UV-C Effectiveness

The effectiveness of germicidal UV depends on the duration, intensity, and wavelength of the UV-C the microorganism is exposed to, and to the organism’s size and opacity.

VirusesBacteriaYeasts
Typical size20-800nm1-10μm5-8μm
Dosage needed1-20mj/cm22-40mj/cm210-30mj/cm2
Avg dose per cm2 Uvisan cabinets (2 mins)68mj/cm268mj/cm268mj/cm2

The rule of thumb is: the larger the microorganism the higher is the UV-C dose required for deactivation (see table above). Uvisan cabinets have been calibrated to be effective using a pre-set 2-minute UV-C exposure time against a wide range of microorganisms, delivering on average many more mj/cm2 than required to deactivate the widest possible range of microorganisms. The cabinets can be programmed for longer cycles too. Uvisan Cleanroom solutions are designed before installation to provide the correct dose for the room to be disinfected.