The Leitz TruSens UV Bulb filter for Z-3000 is an indispensable part of the filter system. The growth of odour-causing microbes and floating organisms trapped in the air filters is reduced by UV light. The UV waves also ensure that bacteria, viruses and protozoa are killed in the germ, preventing them from reproducing and infecting. This lamp is replaced on average every 2 to 3 years.