Ultraviolet Sterilization

Ultraviolet(UV) radiation, under certain conditions, serves as an excellent sterilant. Bacteria, yeasts, molds and viruses are readily
inactivated, provided the cells are accessible to a sufficient UV dose. The biocidal effectiveness of UV radiation emitted from three
different lamps was determined. A particular use of UV radiation for sterilization and the development of a validation system are
discussed in this paper. Also, data supporting the efficacy of UV sterilization are presented.

Ultraviolet (UV) light has proven effective at eliminating the threat from many well known viruses, dating as far back as 1877 when the
first scientific study was recorded concluding that Ultraviolet light provided powerful sterilization properties. Further studies in the
early 20th century confirmed that Ultraviolet light could prevent the spread of infections diseases, on surfaces and in the air, yet it
would take many more decades for science and medicine to harness the power of Ultraviolet radiation.

As sunlight passes through the atmosphere, all UVC and approximately 90% of UVB radiation is absorbed by ozone, water vapour, oxygen and
carbon dioxide. UVA radiation is less affected by the atmosphere. Therefore, the UV radiation reaching the Earth’s surface is largely
composed of UVA with a small UVB component.

The amount of UV radiation from the sun that hits the Earth’s surface depends on several factors, including the sun’s height in the sky,
latitude, cloud cover, altitude, the thickness of the ozone layer and ground reflection. Reductions in the ozone layer due to human-
created pollution increase the amount of UVA and UVB that reaches the surface. This can impact human health, animals, marine organisms and
plant life. In humans, increased UV exposure can cause skin cancers, cataracts and immune system damage.