Sun & skin

          Have you ever wondered why you have been sunburnt on a cloudy day? The total dose of UV radiation reaching the earth’s surface and hence, the potential damage to human skin and tissues, varies, depending on many factors. The sun’s elevation in the sky depends on the time of the day and year. The shorter the distance that photons (making up the total of UV radiation) need to travel though the earth's atmosphere, the greater the intensity of UV radiation. The altitude of a location also effects UV…

Sunburn is the physical response of the skin to damage by overexposure to UV radiation; the duration and intensity of UV radiation corresponds to the severity of the sunburn. UV radiation, specifically the UVB wavelengths, penetrates the skin and burns the tissue, often damaging skin cells beyond repair. For more details on this process, refer to the Sunburn article. Figure 1. Skin damaged by sunburn Sunburn is extremely common, with surveys showing that 42% of people get sunburnt at least once annually. Solar UV radiation is the most common cause of sunburn, yet…

Figure 1. A sunbed/solarium Tanning beds, tanning booths, sunbeds, sunlamps, solaria and solariums are names given to various artificial tanning devices which emit ultraviolet (UV) radiation. Solariums are designed for a person to stand or lie for a period of time in a chamber fitted the length with light tubes which emit UV radiation, this elicits a tanning response from the skin. The use of solariums is particularly prevalent in young people, with 50% of patrons under the age of 29, notably, 71% of users are women.  A common misconception…

Wavelengths of both ultraviolet A (UVA 320–400nm) and ultraviolet B (UVB 280-320nm) radiation have been implicated as carcinogens (cancer causing agents), though their methods of action are distinct. The two wavelengths of radiation are able to penetrate to different depths of the skin and hence affect different cells in the epidermis and dermis: UVB radiation is mainly absorbed by epidermal components such as proteins or deoxyribonucleic acid (DNA), whereas UVA radiation penetrates deeply into the skin and reaches the lower epidermis and dermal fibroblasts. The extent of their effect also…

Skin cancers are malignant growths (malignant tumours or malignant neoplasms), which usually present on the epidermis (the outer layer of skin), though can occur in other areas of the body such as inside the mouth, nose and on the nailbeds. The three most common forms of skin cancer are basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma. Basal cell carcinoma is the most common (accounting for approximately 75% of all skin cancers), though it tends to grow slowly over a number of years and is unlikely to metastasise…

Photoprotection – skin protection from light and UV – is particularly important for young skin for several reasons:  It has been found that the degree of sun exposure and sunburn in childhood is a central factor in the development of skin cancer, especially melanoma, later in life.  Thus, photoprotection of infants and children is crucial to prevent all types of skin cancer and delay photoaging in adulthood. Children spend a substantial amount of time outside compared to adults.  Infants, toddlers and young children are unable to decide on, and implement,…

General characteristics of sunburn A demonstration of sunburn on skin Sunburn is the result of overexposure of skin to ultraviolet (UV) radiation, particularly UVB of wavelengths 280-320nm, which penetrates the skin and causes the tissue to burn. When sunburnt, the epidermis (top layer of the skin) has an immediate (acute) and delayed reaction of redness (erythema), hardening of the skin and, in severe instances, blister formation. This is often accompanied by a general feeling of lethargy or fatigue, which may be attributed to dehydration. Burning of the skin is a…

Photoaging is the premature aging of the skin due to chronic exposure of skin to ultraviolet (UV) light, predominantly from the sun or sun beds. Photoaging ranges from wrinkled, discoloured skin through to precancerous lesions, actinic keratoses. While human skin will naturally age, photoaging, and thus UV, is considered an accelerant to the process. Symptoms Wrinkled, photoaged skin The symptoms of photoaging vary, but are generally recognised as premature degradation of skin on areas where the skin has been exposed long-term to UV light, predominantly on the face and hands,…

Light movement Figure 1. Electromagnetic radiation undergoing refraction, reflection, absorption, and scattering Light can be thought of as energy moving through a space. It is transmitted as particles, photons, from a radiating light source, such as the sun. Photons are packets of mass-less and charge-less energy, and cannot be detected by the human eye. These energy parcels move in a continuous wave-like motion, and are referred to as having wave-particle duality. The amount of energy contained in each photon is directly related to the frequency and subsequent wavelength at which…