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Air Sanitation by Ultraviolet Radiation

Radiation of short wave lengths are more powerful in controlling airborne microorganisms. Among these ultraviolet (UV) is the widely used one. Ultraviolet radiation has a wavelength range of 210-328 nm. The maximum microbicidal effect of UV light is considered to be around 260nm. This wavelength is also the peak absorption wavelength for DNA.

Modem low pressure mercury vapour lamps emit more than 95% of their radiation at 253.7nm and this is at the maximum microbicidal activity. Thus about 50% of the total energy input to the lamp is transmitted as effective UV radiation through the special glass in the lamp. About 2% is transmitted into visible light. The remaining 48% is transformed into heat.