Filtering out UV-B rays almost entirely will effectively eliminate sunburn. But the production of melanin would not be stimulated. This substance is converted into pigment in the cells at the surface of the skin; which darkens under the influence of UV-A light, causing the skin to tan.

The UV-A light of the sun is very slow in causing a tan. Only at intensities higher than those of natural sunlight is UV-A able to tan the skin more quickly. Nowhere on earth can the sun supply UV-A radiation at this level without an accordingly high share of UB-B. Only a high-performance unit with a costly filter and cooling system can generate this level of UV output: The High Pressure 420.