About Ultraviolet Germicidal Irradiation (UVGI)
Ultraviolet (UV) light is one form of electromagnetic energy produced
naturally by the sun. UV is a spectrum of light just below the visible
light and it is split into four distinct spectral areas – Vacuum UV (100
to 200 nm), UVC (200 to 280 nm), UVB (280 to 315 nm) and UVA (315 to 400
nm).
The entire UV spectrum can kill or inactivate many microorganism species,
preventing them from replicating. UVC energy centred around 254 nanometres
provides the most germicidal effect. Hence UVC is also known as
Ultraviolet Germicidal Irradiation (UVGI).
UGVI exposure inactivates microbial organisms such as bacteria and
viruses by altering the structure and the molecular bonds of their DNA
(Deoxyribonucleic acid). DNA is a “blue print” these organisms use to
develop, function and reproduce. By destroying the organism’s ability to
reproduce, it becomes harmless since it cannot colonize. After UVGI
exposure, the organism dies off leaving no offspring, and the population
of the microorganism diminishes rapidly.
Ultraviolet germicidal lamps provide a much more powerful and concentrated
effect of ultraviolet energy than can be found naturally. Such lamps
sanitize air that is passed directly in their path to destroy pathogens
that come in contact with the UV rays. Musty, mouldy odours can be
eradicated, along with airborne disease threats, including emerging
diseases like SARS virus, species-jumping diseases like avian flu and
multi-drug resistant bacterial strains (e.g. MRSA) commonly found in
hospitals.
How UV Lamps Work
Today UVGI is artificially made using specialized lamps producing UVGI at
254 nm.
UVC tubes are filled with argon and mercury gas with electrodes on either
end. A high-voltage electric current runs through the gas between the
electrodes. When one of the electrons from that current strikes a mercury
molecule, part of its energy is absorbed, exciting the mercury. The
mercury then shoots out the energy as a photon of ultraviolet light.
Although UVGI is invisible to the human eye, small amounts of energy
released at visible wavelengths produce the blue glow commonly associated
with UVC lamps