Initial Session Time ??

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OK, as promised I’ve got a little more information about tt (time to tan) and IST (initial session time) for your sunbeds. To recap take a look at previous posts (Amazing Lamps) and (MED and Te). I’ll be using data in this post that was taken from Bed 5 while developing those posts.


QUOTE borrowed from Don Smith: The tt (time to tan) measurement is the time it takes a sunbed to "deliver" the OTD (Optimal Tanning Dose) for the "most sensitive skin type 2" (which is our skin subtype 2A) as calculated by the TAS (Tanning Action Spectrum) we developed at the UVR Research Institute. The TAS "weights" most heavily the wavelengths responsible for the oxidation of melanin, i.e., from 340 nm to 440 nm (UVA).
The Te (time to 4.0 MED) measurement is the time it takes to "deliver" the MAD (Maximum Allowable Dose) of 4.0 MED for "the most sensitive skin type 2" (which is our skin subtype 2A) as calculated by the FDA EAS (Erythemal Action Spectrum). It is the measure of the "sunburning" power of our sunbeds and the wavelengths from 280 nm to 302 nm (the PWR-UVB range) are the most heavily "weighted" by the FDA/EAS.


The OTD for our Skin Type 2A is determined to be .75 MED for the 1st exposure. With that in mind perform the following steps to determine the IST (initial session time) for the sunbed timer.

Divide 0.75 MED by the MED/minute reading calculated for Bed 5, to get the IST (initial session time) for the sunbed.

Example: 0.75 / 0.203 MED/minute = 3.69 (rounded to 4 minutes) IST for "the most sensitive skin type 2, i.e., (our skin subtype 2A).

Divide 4.0 MED by the MED/minute reading calculated for Bed 5, to get the te (time to 4.0 MED) time.

Example: 4.0 MED / 0.203 MED/minute = 19.7 minutes te time.

Thus, the Model 7.0 MED/hour meter is perfectly satisfactory for determining the estimation of IST (time to ).75 MED) and te (time to 4.0 MED) time.

Note that the tt (time to tan) places emphasis on the UVA portion of the TAS (tanning action spectrum), while the Te (time to 4 MED) places emphasis on the UVB portion of the EAS (erythemal action spectrum) due to FDA rules.

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