Different types of germs require different doses for inactivation. Due to the complexity of biological systems and the influence of many factors, different research groups measure different D90 doses for the same germ. A good example of this is the Corona virus, which shows large differences between different research groups. The dose needed to achieve 90% disinfection with LEDs of 275nm is comparable to that needed for Mercury low pressure lamps, for which most studies have been conducted. According to German water sanitation norms, drinking water should be disinfected by 400J/m2.