Ultraviolet rays have a strong ability to reach the dermis layer, tanning the skin, which is very harmful to the skin. Even in the non-summer period, although the intensity of ultraviolet rays is still weak, it still exists, but it can easily cause skin injury due to long-term accumulation Melanin deposits, skin aging and sagging, etc. So beautiful women must apply sunscreen every day. If the following are true, the above conclusions can be weakened most:. ['The amount of ultraviolet radiation in the room half a meter away from the window is about 40% outdoors, and it is attenuated to 15% outdoors at a distance of 1.5 meters from the window.', 'Sunscreen is generally required to be applied evenly and reapplied in time. If it is not used properly, even the products with a nominal high multiple of sun protection may not exert much protection.', 'Ultraviolet intensity is highest in April to September each year, and the weakest in winter.', 'Most parasols have a certain degree of sun protection. An ordinary parasol can block 77% of UV rays, while a black parasol can block 99% of UV rays.']