What is the difference between 10-minute, 20-minute and 30-minute lamps? What would happen if you install a 10-minute lamp in a 20-minute bed?
Perhaps a better question is “What’s the difference between a 10-minute, 20-minute and 30-minute bed?”
An indoor tanning lamp’s performance is directly related to the equipment in which it is installed. In various tanning system models, the same lamp may result in different exposure schedules. Factors such as the transmissive quality of the acrylic shield, the distance of the lamps from the tanner, the ballasts used, bed geometry, electrical current/ voltage, the number and distance between the lamps, and the effectiveness of the unit’s reflector system all influence what the exposure schedule and maximum timer interval will be.
By using a “standard” or “typical” sunbed for evaluation, a lamp manufacturer can estimate a lamp’s TE (exposure time). When consistently applied, this method can provide a pretty good idea of what to expect in your particular application. Given the same sunbed, a “10-minute” lamp will deliver twice the erythemal effectiveness as a “20-minute” lamp. This is usually accomplished by increasing the output of UVB (280-320nm) and UVA2 (320-340 nm) at the expense of UVA1 (340-400nm). Higher wavelength UVB and UVA2 are most closely associated with photoaging (wrinkles), vitamin D synthesis, melanin formation and some pigment darkening. UVA1 penetrates skin more deeply and contributes to robust pigment darkening and longer-lasting tanning results.
To answer the second part of the question, any tanning system, regardless of its timer interval or the lamp type installed may produce a maximum of four MED (minimal erythemal dose). An MED refers to the least amount of UV radiation a person can be exposed to before a distinct erythema or “pinkening” of the skin is induced within 7-24 hours following exposure. Always replace sunlamps with the product listed on the tanning unit label or an FDA compatible alternative. A compatible replacement lamp should not change the exposure schedule by more than +/- 10 percent. Therefore, a compatible replacement lamp for a 20-minute bed should have a TE in the 18-22 minute range (10 percent of 20 minutes is +/-2 minutes). Therefore, a “10-minute” lamp in a 20-minute bed would change the exposure schedule by more than +/-2 minutes and would end up overexposing tanners using that bed unless their session times were reduced. We recommend against replacing a sunbed’s lamps with a non-compatible product.
Remember to use a hand-held UV meter to monitor the depreciation of your sunlamps and replace them when the output drops 30 percent from initial readings.
