Sunlight stimulates the production of vitamin D, helps control some chronic skin conditions (such as psoriasis), and causes a sense of well-being. However, sunlight can damage the skin.

skin under uv light

The damage involves not only painful sunburns, but also wrinkles and other changes associated with skin ageing (photoaging) and (actinic keratoses), skin cancers, and even allergic reactions and exacerbation of certain skin diseases (see photosensitivity reactions).

UV

Although UV rays are invisible to the human eye, they are a component of sunlight that has the strongest effect on the skin. UV light is classified into three types, based on its wavelength:

Ultraviolet A (UVA)

Ultraviolet B (UVB)

Ultraviolet C (UVC)

UV rays (of all kinds) damage deoxyribonucleic acid (DNA - the genetic material in the body), which can eventually lead to cancer. UV rays also cause harmful effects such as premature aging of the skin and premature aging. Also, sunburn can be caused by UV rays, primarily UVB rays. There is no safe level of UV rays.

The amount of ultraviolet radiation reaching the Earth's surface increases, especially in northern latitudes, and this increase is caused by the depletion of the protective ozone layer high in the atmosphere. Ozone, a naturally occurring chemical, blocks much of the ultraviolet radiation from reaching the Earth's surface. To the Earth's surface. Chemical reactions between ozone and CFCs (the chemicals in refrigerants and pressurized aerosol cans) deplete the amount of ozone in the protective ozone layer.

The amount of UV radiation that reaches the Earth's surface also varies based on other factors. UV rays are strongest between 10 a.m. and 3 p.m., during summer and at high altitudes and low latitudes (such as at the equator). Glass, thick clouds, and smoke Smog filters out a lot of ultraviolet rays, but these rays can penetrate clouds and fog and about a foot of clear water, and may cause severe burns.

natural prevention

Certain changes occur in the skin when it is exposed to ultraviolet rays, in order to prevent damage from it, as the epidermis (the top layer of the skin) becomes thicker to prevent the effects of ultraviolet rays. It is a brown pigment that makes the skin darker and leads to its tanning. Tanning provides a natural protection against exposure to ultraviolet rays in the future, because melanin absorbs the energy of these rays and helps prevent the light from causing damage to skin cells and reaching deep into the tissues. Therefore, tanning does not have any health benefits. Tanning with the aim of tanning the skin is dangerous to human health (see Are methods of tanning healthy?).

Sensitivity to sunlight varies according to the amount of melanin in the skin. Dark-skinned people have more melanin, so they have great self-protection against the harmful effects of the sun. However, dark-skinned people are vulnerable to sun damage and the long-term effects of UV exposure. .

Photoaging

Exposure to sunlight causes premature aging of the skin. Damage to the skin caused by prolonged exposure to sunlight is known as photoaging. Exposure to ultraviolet rays leads to fine, rough wrinkles, irregular pigmentation, and large spots, blemishes, and blemishes. Yellow skin color and coarse skin texture.Although people with fair skin are more susceptible, the skin of a person will change with adequate exposure to the sun.

Photoaging

photoaging_high_en

actinic keratoses . actinic keratoses

Actinic keratoses (solar keratoses) are precancerous skin growths that result from prolonged exposure to the sun. These growths are usually pink or red in color, and appear as irregular scaly areas, and may be light gray or hard, brown, and rough and feel Or as if it were sandy.