UVC rays are produced technically using mercury vapour low pressure lamps, in some cases also high pressure lamps. However, till now low pressure lamps have not been beaten in their degree of effectiveness, as they emit more than 90% of their energy in the bactericide effective wavelength area. For this reason sterilAir uses low pressure tubes for germicidal fixtures exclusively.

The remaining rays in a low pressure tube are secondary emissions like light (above 400nm) and heat. The blue glow of a UV lamp therefore says nothing about the degree of emission from a ray source.