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UV-C Production by Germicidal UV Lamps  
 
There are many types of lamps that artificially produce UV.  
 
There are UV lamps for tanning, for counterfeit money detection, black light stage lamps and lamps for mineral displays, lamps that produce Ozone and germicidal UV lamps  
 
UV-C Lamps History and Development  
 
UV-C is artificially produced by mercury vapour low and medium pressure lamps.  
 
The low pressure lamps are most effective, because they emit most of the radiant energy in the germicidal wavelength of 253.7nm also known as the UV-C part of the spectrum.  
 
This is the reason low pressure lamps are mostly used in germicidal UV applications.  
These lamps are sometimes called amalgam lamps because they contain solid amalgam spots (an amalgam is an alloy of mercury with another element, such as indium or gallium) that controls the mercury vapour pressure. 
 
All lamps have secondary emissions, including small amounts of UVA, UVB, visible light (above 400nm wavelength) and heat.  
 
The blue glow of the germicidal UV lamps is not indicative of the effective germicidal output they produce. 
 
As with all gas discharge lamps, the UV-C output of germicidal lamps reduces when the temperature of the lamp surface deviates from the optimum temperature.  
 
The performance data of the various lamp types and the influences of air or water cooling play an important part in an effective and reliable UV-C disinfection. 
 
For effective UV-C disinfection the temperature and the transparency of the lamp for UV-C (253.7nm wavelength) is of great importance. It is important to take the reducing factors under consideration when sizing the UV-C lamps for an effective UV-C disinfecting process.  
Niels Ryberg Finsen (1860-1904) was the first to employ UV rays in treating disease. He was awarded the Nobel Prize for Medicine in 1903. He invented the Finsen curative lamp, which was used successfully through the 1950s.  
 
UV-C was used to disinfect the municipal water supply of Marseille, France, in 1910.  
 
Westinghouse developed the first commercial UV-C germicidal lamps during the 1930s. They were used primarily in hospitals.  
 
After World War II, UV-C was used for sterilizing air in hospitals, kitchens, meat storage and processing plants, bakeries, breweries, dairies, beverage production, pharmaceutical plants and animal labs - anywhere microbiological contamination is a concern.  
 
During the 1950s UV-C was incorporated into air handling equipment. It became a major component in the control and eradication of tuberculosis (TB).  
 
During the 1960’s, concern about microbes lessens with the introduction and increasing availability of new drugs and sterilizing cleaners. As mechanical ventilation becomes more popular, UV-C performance suffers due to the lack of effective UVC performance in cold-air settings. 
 
Technological Improvements- In the 1970’s and 80’s, concerns over chemical use and improvements in UV-C lamp manufacturing caused more organizations and companies to revisit UVGI. In the early 1990’s, UVGI was pioneered into significant water treatment processing for municipal systems as well as for treatment of swimming pools.  
 
The introduction of UV-C into HVAC systems is pioneered in 1996. Recent technological advancements have made it possible for companies to produce high-output ultraviolet germicidal devices further improving efficiency and effectiveness.  
 
UV-C water treatment systems were applied in Austria and Switzerland; by 1985 about 1,500 plants were in use in Europe. In 1998 it was discovered that protozoa such as cryptosporidium and giardia were more vulnerable to UV light than previously thought; this opened the way to wide-scale use of UV water treatment in North America. By 2001, over 6,000 UV water treatment plants were operating in Europe 
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Over the years, UV costs have declined as researchers develop and use new UV methods to disinfect water and wastewater. Currently, several countries have developed regulations that allow systems to disinfect their drinking water supplies with UV light.  
 
ASHRAE covers UVGI and its applications in indoor air quality and building maintenance in "Ultraviolet Lamp Systems", Chapter 16 of its 2008 Handbook, HVAC Systems and Equipment. Its 2011 Handbook, HVAC Applications, covers "Ultraviolet air and surface treatment" in Chapter 60  
 
Recent technological advancements have made it possible for other companies to produce high-output ultraviolet germicidal devices. Through comprehensive testing and research IAQ – Hygienic Energy Solutions has identified a number of manufacturers of UVC lights that function optimally in conditions of cold, moving air to control microbial contamination and thus improve IAQ and HVAC system efficiency.