Described is a device (1) for reducing pollutants in a gaseous mixture comprising: •a containment body (2) having an inlet portion (3) for the gaseous mixture and an outlet portion (4) for the gaseous mixture, the containment body (2) imposing on the gaseous mixture a fixed direction of flow (D), •at least one filtering unit (10) comprising a photocatalytic filter (7) interposed, along the fixed direction of flow (D), between a first light source (6a) and a second light source (6b), both having a wavelength in the visible spectrum (400-700 nm), the photocatalytic filter (7) comprising a photocatalytic nanoparticle coating and the nanoparticle coating comprising titanium dioxide doped with a nitrogen doping agent. •a unit (5) for straightening the flow before the filtering unit (10).