Ultraviolet (UV) radiation is a part of the electromagnetic spectrum with wavelengths ranging between 100 and 400 nanometers (nm). UV radiation is divided into three main categories, each with specific characteristics and distinct impacts on human health and the environment depending on the exposure dose [2]:

1. UV-A (315-400 nm): This is the longest wavelength ultraviolet radiation and accounts for the majority of UV radiation reaching the Earth's surface. UV-A penetrates deeply into the skin and is responsible for the skin aging process, wrinkles and can contribute to the risk of skin cancer. It is also the radiation used in tanning beds.

2. UV-B (280-315 nm): UV-B radiation has a shorter wavelength than UV-A and is more energetic. Some of this radiation is absorbed by ozone in the atmosphere, but a significant fraction still reaches the Earth's surface. UV-B is mainly responsible for sunburn and plays a crucial role in the synthesis of vitamin D in the skin. However, overexposure can cause damage to the DNA of skin cells, increasing the risk of melanoma and other types of skin cancer.

3. UV-C (100-280 nm): This radiation has the shortest wavelength and is the most energetic and potentially dangerous. Fortunately, they are completely absorbed by ozone and oxygen in the Earth's atmosphere, so they do not reach the Earth's surface. UV-C is used in industrial and medical applications to sterilize and disinfect, thanks to its ability to destroy microorganisms.

UV damage [3]

The OMS has identified nine diseases closely linked to exposure to ultraviolet radiation:

1. Cutaneous melanoma, malignant tumor of melanocytes, skin cells that produce skin pigment (melanin)

2. Squamous carcinoma of the skin, a malignant tumor which, compared to melanoma, has a slower evolution and is associated with lower morbidity and mortality

3. Basal cell carcinoma (basal cell carcinoma), a skin cancer that develops mainly at an advanced age and spreads slowly and locally

4. Squamous carcinoma of the cornea or conjunctiva, a rare ocular tumor

5. Keratosis, chronic skin diseases which on rare occasions can generate pre-cancerous lesions

6. Burns

7. Cortical cataract, degeneration of the crystalline lens, which becomes increasingly opaque to the point of compromising vision and which, in certain cases, can even lead to blindness

8. Pterygium, thickening of the conjunctiva leading to clouding of the cornea or limited eye movement

9. Reactivation of cold sores, due to immunosuppression induced by excess UV.

Prevention [3]

• Limit exposure to sunlight as much as possible during the hottest hours, between 10am and 2pm.

• Stay in the shade during the hottest hours, remembering that trees, umbrellas and canopies do not completely protect from sunlight.

• Wear protective clothing: a wide-brimmed hat adequately protects your eyes, ears, face and back of your neck; high protection sunglasses greatly reduce eye risks; tight-fitting, opaque clothing offers additional protection from sunlight.

• Use protective sunscreens (at least +15), reapplying them every two hours or after working, swimming or doing physical activity outdoors. Remember that sunscreens are not used to stay in the sun more, but to protect yourself when exposure is unavoidable.

• Avoid the use of tanning lamps or beds, especially before the age of 18.

• Take into account the UV index, an international scale that correlates the level of UV radiation with the degree of risk: when the index is higher than 3, preventive measures must be implemented.

• Protect children especially, they are more at risk than adults

Positive effects of UV

However, exposure to UV rays does not only have negative effects. This radiation in fact plays an important role in the organic synthesis of Vitamin D, a substance involved in the development of the skeleton and capable of protecting bones from diseases such as rickets, osteomalacia and osteoporosis. In general, minimal exposure to UV rays is enough to obtain these protective effects.

Bibliography

[1] Organizzazione Mondiale della Sanità - OMS (2007), ICF-CY. International classification of functioning, disability and health: Children and youth version, World Health Organization, Geneva (trad. it. ICF-CY. Classificazione Internazionale del Funzionamento, della Disabilità e della Salute – Versione per bambini e adolescenti, Erickson, Trento, 2007). https://cordis.europa.eu/article/id/26092-who-highlights-dangers-of-sunlight/it

[2] Agenzia Zadig, Fondazione AIRC per la Ricerca sul Cancro, pubblicato il 20 maggio 2021, https://www.certifico.com/sicurezza-lavoro/documenti-sicurezza/67-documenti-riservati-sicurezza/4668-classificazione-sostanze-cancerogene-e-mutagene - https://www.airc.it/cancro/prevenzione-tumore/il-sole/raggi-del-sole

[3] Dogliotti E, Achene L, Beccaloni E, Carere M, Comba P, Crebelli R, Lacchetti I, Pasetto R, Soggiu ME, Testai E. Linee guida per la valutazione di impatto sanitario (DL. vo 104/2017). Roma: Istituto Superiore di Sanità; 2019 https://www.epicentro.iss.it/uv/#:~:text=I%20danni%20da%20UV,producono%20il%20pigmento%20cutaneo%20(melanina)