Indoor tanning equipment, like outdoor sunlight, emits UVA (ultraviolet A) and UVB (ultraviolet B) light. Of the UV light emitted by the sun at noon in the summer in the United States: 95 percent is UVA and 5 percent is UVB.
More than 90 percent of professional indoor tanning units emit about 95 percent UVA and 5 percent UVB in regulated dosages similar to summer sun. Recommended exposure schedules developed by the U.S. FDA in cooperation with the tanning industry allow trained indoor tanning operators to set incremental exposure times, based on the “skin type” of a patron, that deliver consistent non-burning dosages of UV light to allow a tanner to gradually build a tan.
The statement that “indoor tanning units are more intense than sunlight” is misleading and inaccurate because the total output of a tanning unit is measured the following way:
Total UV Output = UV Intensity x Duration of Exposure
While tanning units may be 2-3 times as intense as summer sun, the duration of exposure is controlled, and thus the total UV output is controlled, to minimize the risk of sunburn. Exposure times in the more intense tanning units are calculated in similar fashion.
A typical indoor tanning exposure schedule (below) allows a professional indoor tanning operator to gradually increase the exposure times of a tanner over the course of the tanner’s regimen based on the individual’s skin type. – See more at: http://www.tanningtruth.com/#sthash.VCoUgUap.dpuf