Don Smith

Another good e-mail question from a "lurker"
who was "afraid to ask a stupid question" on-line. My advice is to "ask away" because there is no such thing as a stupid question. There are a lot of stupid answers given out "on-line" but no stupid questions!

Back to the subject.

Technically, a "20-minute sunbed" is one that has a te (time to 4.0 MED) time of 20 minutes when measured with a spectroradiometer under standardized conditions. That means that it has an "irradiance" power of 0.2 MED/minute (obtained by dividing 4.0 MED by 20 minutes).

To calculate the IST (Initial Session Time) for this sunbed, divide 0.75 MED by 0.2 MED/minute and you get an IST of 3.75 minutes (rounded to 4 minutes) for a skin subtype 2A (the most sensitive skin type 2).

HOWEVER, many sunbeds are "marketed" as 20 minute sunbeds although they do not "test out" at delivering 4.0 MED in 20 minutes. Thus, if a manufacturer sold you a so-called "20-minute sunbed" that reached 4.0 MED in 25 minutes (0.16 MED/minute) it means that it only "performs" at 80% of it's stated capacity and they should tell you that important fact BEFORE YOU BUY IT. Does this happen? Sadly, no in most cases.

Therefore, in your "due diligence" before parting with your hard-earned money, ASK the manufacturer for a copy of the data they submitted to FDA stating the te (time to 4.0 MED) time. If they won't (or can't) give it to you, better buy from someone who can (and will!) give it to you!

The "bottom line" is that all 20-minute sunbeds DO NOT perform the same!

FYI, the "fastest" that a 20-minute sunbed can reach 4.0 MED and still be in compliance with current FDA regulations is 18 minutes (0.22 MED/minute).

Hope this helps and I hope you will feel free to ask questions "on-line" in the future.

Don

BooBop

Wow Don, very interesting. Thanks to whoever asked this question. I learned from it also.