. At that time in the West, the upper social class used parasols, long sleeves and hats to avoid sunlight's tanning effects. In the United States and Western Europe before the 1920s, tanned skin was associated with the lower classes because they worked outdoors and were exposed to the sunlight. Parasols and long sleeves were typically worn, even at beaches. In 1903,
Niels Finsen was awarded the Nobel Prize in Medicine for his "Finsen Light Therapy". The therapy was a cure for diseases such as
lupus vulgaris and
rickets.
Vitamin D deficiency was found to be a cause of rickets, and exposure to sunlight would allow vitamin D to be produced in a person. Therefore, sunlight exposure was a remedy for curing several diseases, especially rickets. In 1910 a scientific expedition went to the island of
Tenerife to test the wider health benefits of "heliotherapy", and by 1913 "sunbathing" was referred to as a desirable activity for the leisured class. Shortly thereafter, in the 1920s, fashion designer
Coco Chanel accidentally got sunburnt while visiting the
French Riviera. When she arrived home, she arrived with a sun tan, and her fans apparently liked the look and started to adopt darker skin tones themselves. Tanned skin became a trend partly because of Coco's status and the longing for her lifestyle by other members of society. In addition, Parisians fell in love with
Josephine Baker, a "caramel-skinned" singer in
Paris, and idolized her darker skin. These two women were leading figures of the transformation that tan skin underwent, in which it became perceived as fashionable, healthy, and luxurious.
Jean Patou capitalized on the new tanning fad, launching the first sun tan oil "Huile de Chaldee" in 1927. Just before the 1930s, sunlight therapy became a popularly subscribed cure for almost every ailment from simple fatigue to tuberculosis. In the 1940s, advertisements encouraging sunbathing began to appear in women's magazines. At the same time,
swimsuits' skin coverage began decreasing, with the
bikini radically changing swimsuit style after it made its appearance in 1946. In the 1950s,
baby oil was commonly used to increase tanning.
Coppertone, in 1953, marketed its sunscreen with a drawing of a young girl and her cocker spaniel tugging on her bathing suit bottom, revealing her bare bottom and tan line; this advertisement was modified around the turn of the 21st century and now shows a little girl wearing a one-piece bathing suit or shorts. In the latter part of the 1950s, silver metallic reflectors were common to enhance one's tan. In 1962, sunscreen commenced to be
SPF rated, although SPF labeling in the US was not standardized by the FDA until 1978. In the 1970s,
Mattel introduced Malibu
Barbie, which had tanned skin and further popularized sun tanning among women. In 1978, both sunscreens with an SPF 15 rating as well as
tanning beds first appeared. In 2007, there were an estimated 50,000 outlets for indoor tanning; it was a five-billion-dollar industry in the United States, and had spawned an auxiliary industry for
indoor tanning lotions including bronzers, intensifiers, and accelerators. Since then, the indoor tanning industry has become more constrained by health regulations. In China, darker skin is still considered by many to be the mark of the lower classes. As recently as 2012, in some parts of China,
ski masks were becoming popular items to wear at the beach in order to protect the wearer's face from the effects of sunlight. A 1969 innovation is
tan-through swimwear, which uses fabric perforated with thousands of micro holes that are nearly invisible to the naked eye, but which transmit enough sunlight to approach an all-over tan, especially if the fabric is stretched taut. Tan-through swimwear typically allows more than one-third of UV rays to pass through (equivalent to SPF 3 or less), and an application of sunscreen even to the covered area is recommended. ==Sunless tanning==