Whether ultraviolet rays are harmful to the human body depends on the dosage. Darker skin can help give a person added protection the next time they're out in the sun. Essentially, the skin produces its own natural sunscreen. Proper use of ultraviolet light or moderate exposure to ultraviolet light has the following benefits to the human body:

1. Sterilization

Ultraviolet rays may destroy the molecular structure of DNA and RNA in microbial cells, leading to the death of growing cells or the death of regenerative cells, thereby achieving the purpose of sterilization. Certain skin disorders can be treated with ultraviolet radiation. With modern phototherapy, eczema, dermatitis, jaundice, psoriasis and vitiligo can now be successfully treated. In daily life, sunbathing kills bacteria on the skin and prevents skin diseases such as boils and folliculitis. Expose the indoor space to sunlight and dry the bedding frequently, which can reduce the spread of diseases.

2. Boosts Vitamin D Synthesis

Human skin contains sterols, which can be converted into vitamin D by ultraviolet radiation in the sun. Proper exposure to the sun can promote the synthesis of vitamin D in human cells, which helps regulate calcium metabolism, insulin secretion, blood pressure, immunity and cell reproduction. Therefore, ultraviolet rays can prevent and treat high blood pressure, rickets, osteomalacia and osteoporosis, but excessive exposure to ultraviolet rays to the skin should be avoided, otherwise it may cause skin damage. Vitamin D also boosts the production of serotonin, which is directly proportional to the body's exposure to UV radiation. Changes in serotonin levels can affect mood and behavior.

3. Improve Skin Condition

A kind of basal cells are distributed in the epidermis of the human body, moderate ultraviolet radiation will increase the amount of melanin in these cells, and they are deposited on the surface of the skin, making the skin uniformly dark brown. This is the reason why sun tans your skin. Melanin can absorb more light energy, quickly convert it into heat energy, and stimulate sweat gland secretion to dissipate heat, which can protect the skin from direct and indirect DNA damage. Ultraviolet rays can also promote local blood circulation, and can also act on the epidermis to promote the regeneration of damaged epidermis, thereby acting as an analgesic. Generally, it has a better relief effect on inflammatory pain and non-inflammatory pain.

4. Enhance the Body's Immunity

Ultraviolet radiation in sunlight can stimulate the body's hematopoietic function, increase the number of red blood cells, increase hemoglobin, improve the quality of red blood cells, improve muscle activity, increase the body's immunity, promote the body's ability to absorb oxygen and metabolism, and relieve asthma and Joint pain,enhance physical fitness.

The harm of ultraviolet rays to the human body mainly includes the following situations:

1. Skin Cancer

Since photoaging of the skin is cumulative, it's never too late to start a sun protection regimen. Long-term high-dose ultraviolet radiation will accelerate the aging of the skin, causing symptoms such as redness, pain, itching, and desquamation of the local skin, resulting in the deposition of pigments, causing sunburn, freckles, etc., and may even induce skin cancer . Research shows that up to 90 percent of skin cancers are caused by UV radiation.

2. Solar Dermatitis

Excessive exposure of the skin to UV rays can cause an inflammatory response. UV rays burn the skin, and when skin cells are damaged, extra blood flows to the damaged skin to try to repair it, which is why when you get sunburned your skin appears red and feels hot and painful. In severe cases, symptoms such as blisters, and some patients may also experience symptoms such as nausea, vomiting, headache, and fever.

3. Damage to Eyes

Prolonged exposure to ultraviolet rays can damage eye tissue, causing symptoms such as stinging, redness, tearing, and even cataracts. Patients may present with decreased vision, decreased color sensitivity, and blurred vision. Even small amounts of sunlight can increase your risk of eye damage. The damage of ultraviolet rays to the eyes is cumulative, and it is never too late to start protecting the eyes.