Indoor tanning involves using a device that emits ultraviolet radiation to produce a cosmetic tan. Typically found in tanning salons, gyms, spas, hotels, and sporting facilities, and less often in private residences, the most common device is a horizontal tanning bed, also known as a sunbed or solarium. Vertical devices are known as tanning booths or stand-up sunbeds. Indoor tanning became widespread in the Western world in the late 1970s. The practice finds a cultural parallel in skin whitening in Asian countries, and both support multibillion-dollar industries. Most indoor tanners are women, 16–25 years old, who want to improve their appearance or mood, acquire a pre-holiday tan, or treat a skin condition. Indoor tanning increases the risk of developing skin cancer. As such, the number and usage of tanning facilities have declined, and many countries have either banned the practice outright or for people under 18 years of age.
Background
Ultraviolet radiation
Ultraviolet radiation (UVR) is part of the electromagnetic spectrum, just beyond visible light. Ultraviolet wavelengths are 100 to 400 nanometres (nm, billionths of a metre) and are divided into three bands: A, B, and C. UVA wavelengths are the longest, 315 to 400 nm; UVB are 280 to 315 nm, and UVC wavelengths are the shortest, 100 to 280 nm. About 95% of the UVR that reaches Earth from the sun is UVA and 5% UVB; no appreciable UVC reaches Earth. While tanning systems before the 1970s produced some UVC, modern tanning devices produce no UVC, a small amount of UVB and mostly UVA. Classified by the WHO as a group 1 carcinogen, UV radiation has "complex and mixed effects on human health". While it causes skin cancer and other damage, including skin aging or creases such as wrinkles, it also triggers the synthesis of vitamin D and endorphins in the skin.
History
In 1890, the Danish physician Niels Ryberg Finsen developed a carbon arc lamp ("Finsen's light" or a "Finsen lamp") that produced ultraviolet radiation for use in skin therapy, including to treat lupus vulgaris. He won the 1903 Nobel Prize in Physiology or Medicine for his work. Until the 20th century, pale skin was a symbol of high social class among white people in Europe and the United States. Victorian women would carry parasols and wear wide-brimmed hats and gloves; their homes featured heavy curtains that kept out the sun. But as the working classes moved from country work to city factories, and to crowded, dark, unsanitary homes, pale skin became increasingly associated with poverty and ill health. In 1923, Coco Chanel returned from a holiday in Cannes with a tan, later telling Vogue magazine: "A golden tan is the index of chic!" Tanned skin had become a fashion accessory. In parallel, physicians began advising their patients on the benefits of the "sun cure", citing its antiseptic properties. Sunshine was promoted as a treatment for depression, diabetes, constipation, pneumonia, high and low blood pressure, and many other ailments. Home-tanning equipment was introduced in the 1920s in the form of "sunlamps" or "health lamps", UV lamps that emitted a large percentage of UVB, leading to burns. Friedrich Wolff, a German scientist and hailed as the "father of indoor tanning", began using UV light on athletes, and developed beds that emitted 95% UVA and 5% UVB, which reduced the likelihood of burning. In 1975, Wolff invented the sunbed. A tanning salon was opened two years later in Berlin, followed by tanning salons in Europe and North America in the late 1970s. In 1978, Wolff's devices began selling in the United States, and the indoor tanning industry was born.
Devices
Lamps
Tanning lamps, also known as tanning bulbs or tanning tubes, produce the ultraviolet light in tanning devices. The performance (or output) varies widely between brands and styles. Most are low-pressure fluorescent tubes, but high-pressure bulbs also exist. The electronics systems and the number of lamps affect performance, but to a lesser degree than the lamp itself. Tanning lamps are regulated separately from tanning beds in most countries, as they are the consumable portion of the system.
Beds
Most tanning beds are horizontal enclosures with a bench and canopy (lid) that house long, low-pressure fluorescent bulbs (100–200 watts) under an acrylic surface. The tanner is surrounded by bulbs when the canopy is closed. Modern tanning beds emit mostly UVA (the sun emits around 95% UVA and 5% UVB). One review of studies found that the UVB irradiance of beds was on average lower than the summer sun at latitudes 37°S to 35°N, but that UVA irradiance was on average much higher. The user sets a timer (or it is set remotely by the salon operator), lies on the bed, and pulls down the canopy. The maximum exposure time for most low-pressure beds is 15–20 minutes. In the US, maximum times are set by the manufacturer according to how long it takes to produce four "minimal erythema doses" (MEDs), an upper limit laid down by the FDA. An MED is the amount of UV radiation that will produce erythema (redness of the skin) within a few hours of exposure. High-pressure beds use smaller, higher-wattage quartz bulbs and emit a higher percentage of UVA. They may emit 10–15 times more UVA than the midday sun, and have a shorter maximum exposure time (typically 10–12 minutes). UVA gives an immediate, short-term tan by bronzing melanin in the skin, but no new melanin is formed. UVB has no immediate bronzing effect. However, a 72-hour delay allows the skin to produce new melanin, leading to longer-lasting tans. UVA is less likely to cause burning or dry skin than UVB, but is associated with wrinkling and loss of elasticity because it penetrates deeper. Commercial tanning beds cost $6,000 to $30,000 as of 2006, with high-pressure beds at the high end.
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