Long-term sun exposure needs to be judged based on the intensity of the sunlight, the length of exposure, etc. to determine whether it is harmful to the human body. Moderate exposure is beneficial to the human body, while over-exposure may affect multiple organs such as the skin and eyes. Although sun exposure can help the body to replenish vitamin D and prevent calcium deficiency, it is only based on proper sun exposure. If you regularly sunbathe without any sun protection, both UVA and UVB rays can penetrate the atmosphere and damage human skin, leading to cellular aging and skin pigmentation. Currently for how long the sun is considered excessive, there is no exact regulation, but generally believe that the length of daily direct sun exposure to half an hour is appropriate. Of course, due to skin color, physical and other reasons, the specific tolerance length is not uniform, but generally best not to exceed 2 1/2 hours. In addition, strong, long sun exposure may also increase the probability of skin cancer. Long-term sun exposure can also damage the eyes, increasing the risk of cataracts and other eye diseases. Intense ultraviolet radiation in the summer may also lead to heat stroke, sunburn and other conditions, and can also develop solar dermatitis, which is an allergy to light. Therefore, it is recommended that you should maintain moderate sun exposure in your daily life and not expose yourself to the sun for any length of time. When you are outdoors and the ultraviolet rays are strong, you should take sun protection measures, such as applying sunscreen, wearing sunglasses, playing umbrellas, wearing sun hats, wearing sun-protective clothing and so on.