Lamp with UV for the photo catalysis on air purifier HENRY. The photo catalyses enable realizing chemical reactions in the presence of light. It is an electronic process which occurs on the surface of a catalyst (the dioxide of titanium - TiO2) by the intervention of an UV radiation. The polluting particles are absorbed on the surface of the catalyst to be oxidized. It is the photons which create sites of oxidation and reduction on the surface of the catalyst. Process provokes the break of the chemical connections of biological pollutants and COV, which then degrades in H2O and CO2. This treatment by photo catalysis is strengthened by the effect germicide appropriate for UV radiation. Any organic sort (micro-organism, contaminating chemical, and smell) is so destroyed independently of its molecular structure, what makes of the photo catalysis a method of very successful destruction. This oxidation photo catalytic is a process which knows an interest growing for some years, by implying at room temperature the generation of highly reagent oxidizing radicals, which react typically between a million and a billion times more quickly than most of the oxidizing classic agent as the ozone and the hydrogen peroxide. The photo catalysis open perspectives in treatment of pollutants in gaseous effluents, such as the air, or in the water. It is thus the process which we use in the quasi-totality of our products of purification of the air, and our dehumidifiers.