Prof. Dr. Katerina Damevska
Spec. in Dermatovenerology
PHI University Clinic for Dermatology, Cyril and Methodius University, Skopje
How to enjoy the sun while keeping your skin protected?
The sun is highly beneficial to our overall health. In small doses, it has positive effects, such as
synthesis of vitamin D and antidepressant effect. In some skin diseases, such as psoriasis, it is
used as therapy, but in controlled doses and with controlled duration.
To enjoy the sun, it is vital to understand and prevent its side effects such as premature aging and skin cancer.
Sunlight is an electromagnetic waves spectrum: ultraviolet (UV), visible light, and infrared waves. UV rays are divided into UVA (315 - 400 nm), UVB (280 - 315 nm) and UVC (100 - 280 nm) and affect the skin differently. UVC rays do not travel through the atmosphere’s ozone layer and do not significantly affect the skin.
Phototypes are defined according to natural characteristics (color of skin, eyes, and hair), as well
as how the sun affects the skin. People with a light phototype (I and II) are more sensitive to the
sun in general. People with dark phototypes (V and VI) have stronger sun resistance and a lower
incidence of skin cancer due to natural melanin protection.
Dark-skinned people's epidermal melanin filters twice as much UVB as in people with white skin. Thus, the epidermis of dark-skinned people lets through 7 to 17% of UVB rays, compared to the epidermis of white-skinned people, which lets through 25 to 55%. This is due to larger and more melanized melanosomes, which have the power to absorb a greater amount of sun rays. The amount of UV rays necessary to cause for the skin to burn is about 30 times higher in persons of dark phototypes.
Skin aging is the result of internal and external factors.
Intrinsic (internal) aging is a physiological process that results in thinner, dry skin with delicate wrinkles, as well as reduced elasticity. Intrinsic aging begins in the mid-twenties, but is not immediately noticeable. At first, collagen and elastin production decreases and the regenerative processes slow down. Such biological aging is gradual, slow, and inevitable.
Extrinsic (external) aging results from long-term skin exposure to harmful influences, such as smoking, poor nutrition, and air pollution. These factors accumulate and add up to intrinsic aging. However, the strongest factor is prolonged and intense exposure to UV rays, giving rise to the term photoaging. There is irrefutable scientific evidence that UV rays cause structural changes in collagen, elastin and proteoglycans, which are essential for the skin’s elasticity and hydration, giving it its youthful appearance.
The mechanism by which UV rays cause skin aging is known and is basically a low-intensity chronic inflammation, similar to other pathological processes of accelerated aging, such as osteoporosis, type 2 diabetes or Alzheimer's disease. In essence, UV rays cause oxidative stress and damage to cells in the epidermis and dermis, causing inflammation that further damages the cells.
Since we cannot significantly affect the skin’s intrinsic biological aging, the only option is to lessen the impact of external factors, the most significant of which is the impact of UVA and UVB rays.
Signs of photoaging
Young skin is evenly pigmented. Skin exposed to UV rays is unevenly pigmented, especially in the regions that are exposed the most (face, neck, lower arms, and lower legs), where areas of reduced pigmentation (white spots, hypopigmentation) and areas of increased pigmentation (sun spots, hyperpigmentation) are noticeable. Overall, the skin’s mottling adds to the impression of old/prematurely aged skin. It is possible to eliminate the melanin pigment using various cosmetic procedures when it is found in the epidermis’ surface layers. Deep-seated melanin, however, is permanent and difficult to remove.
Unlike biological wrinkles which often appear as soft folds, mainly around the eyes and lips, wrinkles from UV rays appear as harsh, deep furrows. They develop as a result of long-term damage to the elastic dermal fibers, primarily from UVA rays that deeply penetrate the dermis. Since deep wrinkles from photoaging develop in the deep parts of the dermis, they are difficult or impossible to treat cosmetically (by using creams).
Telangiectasias, which are dilated blood vessels, are brought on by skin (thinning) atrophy. As result of biological aging, they can be observed after the fifth decade. They manifest much earlier and with greater intensity when caused by UVA rays. They appear as red sports or tiny dilated capillaries adding to the skin’s colored appearance. When incipient and discrete, they may be reversible or may respond well to cosmetic procedures. However, persistent capillary dilation brought on by UV exposure makes cosmetic correction difficult or even impossible.
Risk of skin cancer
UV rays have been linked to skin cancers, such as malignant melanoma (MM), basal cell
carcinoma (BCC), and squamous cell carcinoma (SCC). There is strong scientific evidence that
these cancers are linked to sun exposure. It is estimated that about 65% of MM and over 90% of
BCC and SCC occur as a result of sun exposure. The primary mechanism of occurrence is UV-
induced DNA mutation.
Melanoma is the rarest (1%) of skin cancers, but also the deadliest, refractory to treatments and with remarkable capacity for early metastases. If detected early, it can be completely cured by surgical removal. The number of MM cases has been increasing in recent decades, especially among the white population living in sunny regions of the world. Most MMs develop from existing nevi (moles), although they can also appear as a new lesion. It is an undeniable fact that UV rays contribute significantly to the onset of MM.
BCC and SCC are cancers that originate from epidermal keratinocytes. They are very common, but have a better prognosis due to their poor tendency to metastasize. Both cancers occur in sun- exposed regions, which supports the role of UV rays in their development.
Prolonged and frequent exposure to UV rays damages the DNA of epidermal cells and creates
conditions for mutations. Namely, when DNA excessively absorbs photons from UVB rays,
structural changes occur in the nucleus. The organism has mechanisms to repair the damage, but
once they are exhausted, conditions develop for permanent DNA damage and cancer cells
Most studies show that the use of sun protection products prevents DNA damage and significantly reduces the risk of melanoma and squamous cell carcinoma.
How to protect yourself?
Minimize exposure to direct sunlight, especially between 10 a.m. and 4 p.m.
Wear protective clothing, hat, and sunglasses.
Use sun protection products. Choose a sunscreen that provides both UVB and UVA protection.
A number of studies show that regular use of skin protection products reduces the occurrence of photodamage and skin cancers.
The American Association of Dermatologists recommends using broad-spectrum products that protect against UVA and UVB rays, with sun protection factor (SPF) of at least 15, which should be applied every 2 hours if you stay outdoors. The recommendation also applies to cloudy days.
Use of sun protection products in children. The American and European Academy of Dermatology recommend using sun protection products in children over 6 months.
Use protection factor (SPF) suitable to your phototype.
Protect yourself even on cloudy days and when being in the mountains.
Protect yourself in winter, as well. UVA rays are present throughout the year and in all seasons. They have the power to reflect off bodies of water or snow.
Use products with SPF of at least 15