The invention relates to an arrangement for optimally adjusting the UVB to UVA ratio of artificial UV light, particularly for solar cosmetic purposes, comprising at least one light source emitting in both the UVB and UVA wavelength ranges, where the major part of spectral power of the light source falls in the range between 321-400 nm, preferably between 321-365 nm, and where at least one single-layer UV filter is arranged between the light source and the irradiated surface, The invention is essentially characterised by that the transmittance of the at least one UV filter at the wavelength of 305 nm or below is lower than 5% and at the wavelength of 320 nm or above is greater than or equal to 59%, with the transmission of the filter at the wavelength of 313 nm being in the range of 12-59%. The UV filter according to the invention comes near the UVB to UVA ratio that is optimal from the aspect of tanning efficiency by providing that the transmittance curve (3) has a steeper upward slope than the transmittance curves of known filters.
