Sun protection refers to the measures taken to safeguard the skin from the harmful impact of ultraviolet (UV) radiation emitted by the sun. UV radiation consists of different wavelengths, including UVA and UVB rays, which can cause various detrimental effects on the skin.

While UV radiation poses a significant concern, visible light is generally not considered problematic unless in specific cases of photosensitivity disorders such as porphyrias.

Solar ultraviolet (UV) radiation is classified into UVA, UVB, and UVC based on their respective wavelength ranges. UVC, with a wavelength of 100-280 nm, is mostly absorbed by the atmosphere. UVB, ranging from 290-320 nm, reaches the Earth’s surface, and UVA, with a wavelength of 320-400 nm, also reaches the Earth’s surface. Exposure to UVA and UVB radiation is associated with skin aging and is the primary cause of skin cancer, including basal cell carcinoma, squamous cell carcinoma, and melanoma. UVB radiation specifically leads to skin reddening, sunburn, and damage to the upper layers of the skin.

Although visible light falls within a longer wavelength range of 400-750 nm, it can trigger or worsen certain photodermatoses, such as melasma, postinflammatory hyperpigmentation, lichen planus pigmentosus, solar urticaria, cutaneous porphyrias, and chronic actinic dermatitis.

To mitigate these damaging effects, sun protection methods, including the use of sunscreen and sun-protective clothing, are essential. Sunscreens are topical agents that protect against UV radiation, and their efficacy is measured by the sun protection factor (SPF), which reflects their ability to shield against UVB rays. Broad-spectrum sunscreens also provide protection against UVA wavelengths. It is recommended to use sunscreen daily when the ultraviolet index is 3 or higher and to reapply it at least every 2 hours. Sun-protective clothing, including garments made from UV-protective fabric, can provide additional protection. Seeking shade and minimizing sun exposure during peak sunshine hours, along with the use of eyewear, such as sunglasses or UV-filtering prescription glasses, further contribute to sun protection. Proper eyewear helps to safeguard the eyes and eyelids from solar UVR exposure, which is a risk factor for various eye diseases.

It is worth noting that the use of sun protection measures should be started early in life, as a significant portion of lifetime UV exposure occurs before the age of 10.

Certain agents have been found to possess photoprotective and anti-photocarcinogenic properties. These include niacinamide, afamelanotide, and Polypodium leucotomos extract. 

Nicotinamide, a derivative of Vitamin B3, has shown promising effects in protecting the skin against the harmful effects of UV radiation. It has been found to enhance DNA repair mechanisms, reduce UV-induced immunosuppression, and prevent the development of non-melanoma skin cancers.

Afamelanotide is an analogue of alpha-melanocyte-stimulating hormone (a-MSH), which is involved in regulating melanin production. It stimulates melanin synthesis in the skin, providing natural photoprotection against UV radiation. Afamelanotide has shown efficacy in preventing phototoxic reactions, such as polymorphic light eruption and reducing the risk of skin cancers in individuals with certain genetic disorders.

Polypodium leucotomos is a fern plant extract that has demonstrated photoprotective properties. It has antioxidant and anti-inflammatory effects, scavenging free radicals generated by UV radiation and reducing UV-induced skin damage. Polypodium leucotomos extract has been studied for its potential to prevent photodermatoses, minimise sunburn, and protect against skin cancer development.

Maintaining adequate levels of Vitamin D is crucial for bone health and calcium regulation. Some concerns have been raised regarding the potential impact of sunscreen use on Vitamin D production, as it blocks UVB radiation, which is involved in the synthesis of Vitamin D in the skin.

However, studies have shown that regular use of sunscreen in real-life scenarios does not lead to significant Vitamin D deficiency. If there are concerns about Vitamin D levels, oral Vitamin D supplements are available as a supplement.

The following recommendations are advised to protect against sunburn and maintain Vitamin D levels: 

Sunscreen with a high sun protection factor (SPF) and broad-spectrum coverage should be applied on a daily basis, especially when the ultraviolet index is 3 or higher.

Reapply sunscreen every two hours, and after swimming or heavy sweating.

Sun exposure during peak sunshine hours, typically between 10 am and 4 pm should be minimized in the summer. Whenever possible, individuals should seek shade and limit time spent in direct sunlight.

Deliberate sun tanning should be avoided, as it increases the risk of skin damage and skin cancer.

Clothing made from tightly woven fabrics in darker colors is recommended, as it provides better sun protection. Additionally, clothing that covers more skin and has a UPF (UV protection factor) of 30 or higher is recommended.

After swimming or getting wet, dry clothes should be put on, as wet material offers less protection from UV radiation.

Precautions to protect the skin and eyes at high altitudes, regardless of the season, should be taken. In snowy conditions, extra caution is needed as snow reflects UV radiation, increasing exposure.

By following these recommendations, individuals can strike a balance between protecting their skin from the harmful effects of UV radiation and maintaining adequate Vitamin D levels for overall health.