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The ultraviolet index, or UV index, is an international standard measurement of the strength of the sunburn -producing ultraviolet (UV) radiation at a particular place and time. It is primarily used in daily and hourly forecasts aimed at the general public. The UV index is designed as an open-ended linear scale, directly proportional to the ...
Blood levels of folate, a nutrient vital for fetal development, can be degraded by UV radiation, [55] raising concerns about sun exposure for pregnant women. [56] Lifespan and fertility can be adversely affected for individuals born during peaks of the 11-year solar cycle, possibly because of UV-related folate deficiency during gestation. [57]
Vitamin D deficiency is typically diagnosed by measuring the concentration of the 25-hydroxyvitamin D in the blood, which is the most accurate measure of stores of vitamin D in the body. [ 1][ 7][ 2] One nanogram per millilitre ( 1 ng/mL) is equivalent to 2.5 nanomoles per litre ( 2.5 nmol/L ). Severe deficiency: < 12 ng/mL = < 30 nmol/L[ 2 ...
Sun damage can show up in different ways, and it can be acute — meaning, you see the damage right away — or chronic, meaning it develops after prolonged exposure to UV rays. An obvious acute ...
At ground level with the sun at zenith, sunlight is 44% visible light, 3% ultraviolet, and the remainder infrared. [ 22 ] [ 23 ] Of the ultraviolet radiation that reaches the Earth's surface, more than 95% is the longer wavelengths of UVA, with the small remainder UVB.
Myth 2: Your body needs vitamin D, and sunscreen will keep you from getting it. The reality: It only takes a small amount of sun exposure to produce all the vitamin D your body needs. One study of ...
Exposure to light through windows is insufficient because glass almost completely blocks UVB light. [178] Adequate amounts of vitamin D can be produced with moderate sun exposure to the face, arms and legs (for those with the least melanin), averaging 5–30 minutes twice per week, or approximately 25% of the time for minimal sunburn.
Ultraviolet light therapy or ultraviolet phototherapy is a treatment for psoriasis, atopic skin disorder, vitiligo and other skin diseases. There are two main treatments: UVB that is the most common, and PUVA. There are four UVB types of lamps: Fluorescnt Broad-Band UVB that emit 280-330 nanometer, Fluorescent Narrow-Band that emit 312 ...