The sunlight that illuminates our world is necessary for the maintenance of life. It is known that natural sunlight improves the quality of life, has a positive effect on psychological state, and plays a role in vitamin D synthesis. The rays that make up the solar spectrum are gamma rays, A number of physiological and pathological consequences occur with the absorption of ultraviolet (UV) rays by the skin.
UVA: Its wavelength is in the range of 320-400 nm and constitutes 95% of ultraviolet energy. The most important effects are erythema (skin redness) and tanning. UVA reaches the lower layer of the skin, causing skin aging (photoaging) due to sunlight and triggering skin cancer. UVA is mostly responsible for drug reactions triggered by sunlight. UVA has less intensity variability during the day than UVB and is less affected by latitude and atmospheric conditions. It can pass through window glass.
UVB: Its wavelength is in the range of 290-320 nm. UV rays are primarily responsible for sunburns. It is carcinogenic and plays a major role in photoaging. UVB is retained by window glass but can pass through quartz glass and water. Approximately 72% of the UVB dose exposed throughout the year is received in the summer months.
UVC: Wavelength is in the range of 200-290 nm. It has a killing effect on bacteria. It is used in germicidal lamps.
As the sun's rays pass through the atmosphere, all of the UCV and approximately 90% of the UVB are captured by water vapor, ozone, oxygen and carbon dioxide. UVA is little affected by atmospheric conditions. In this case, the majority of the UV reaching the earth is UVA and a small portion is UVB.
As we mentioned at the beginning of our article, in addition to the vital beneficial effects of sun rays, their undesirable side effects are too numerous to be underestimated. The main ones are sunburn, hyperpigmentation (dark color change on the skin), photoaging, photocarcinogenesis, phototoxic and photoallergic skin diseases, suppression of the skin immune system and cataract formation.
Undesirable effects. To be most protected, we must consciously benefit from sunlight. In the summer months, when the sun reaches the earth at a right angle, 20 minutes of daily sun exposure of our arms and legs without sunscreen is sufficient for daily vitamin D synthesis. With the increase in various devices that emit artificial UV, people are exposed to UV intensively, and in parallel, the harmful effects of UV have increased in recent years. Skin cancers are a growing health problem. 80% of the total sunlight received throughout life is received in childhood. Therefore, it is very important to take the necessary precautions to protect children and young adults from the sun.
Our skin has a number of natural protective systems against the undesirable harmful effects of UV. These protection systems are hair on the scalp, lipids (oils) on the skin surface, urosanic acid secretion in sweat, the protective upper layer of the skin called stratum corneum, beta carotene (free radical scavenger), melanin, antioxidant enzymes, and DNA repair system. However, these protective systems are not sufficient and additional protective measures are needed. The main protective measures are the use of sunscreen creams, sun-protective clothing, hats and glasses.
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