Peak ultraviolet response
bandwidth: 280-298 nm
Total UVR response: <280-400nm, Diffey EAS
Display: 3.5 digit LCD
Resolution: 1 IU/minute
Power Source: 9V DC battery
Accuracy: Eeff ± 10% ref NIST. Vit D3 approximate.
Proper usage of Solar meter Vitamin D3 IU per Minute International Units (IU) of natural vitamin D3 (converted from 7-DHC) per minute of ultraviolet B exposure instructions:
This instrument is designed for both outdoor solar measurement and indoor UVR appliance measurement. The sensor/detector response follows the Diffey Erythemal Action Spectrum (EAS) effective irradiance (Eeff), and thus remains accurate for various spectral power distributions. Eeff is used here as a proxy for Vitamin D action spectrum weighted irradiance (Deff), which is very similar but cuts off at 330 nm. Spectral radiometer tests have shown Eeff and Deff to be virtually linearly proportional outdoors ± ~4 hours from solar noon, and indoors for most commonly used UVR lamps.
The formula constants embedded in the UTILITY conversions of meter readings with IU and Eeff dose rates are:
> 1000 IU = 1 Med.
> 1 IU/min = 1/1000 Med/min (or .06 Med/hr, which = 1/16.666 Med/hr).
> 1 Med/hr = 2.333333 UVI and 1 Med/hr = 16.66666 IU/min.
Thus the conversion constant for IU/min to UVI is 16.66666666 / 2.3333333 = 7.14285714285.
Formulas for other parameters (skin type, tan level, age, etc are footnoted and available on request).
How to use the meter:
For the casual user seeking about 1000 IU from face/arms exposure, there is no need to use the spreadsheet parameters. Simply point the meter at UV source and divide the reading into 1000 for minutes of exposure. Done. Cautionary note: if you are white type 2 skin (usually burns, sometimes tans) start out at 50-75% of calculated minutes until your tolerance to UVR increases after about 4 exposures. If you are higher skin type and/or have a base tan, you will synthesize less than 1000 IU.
For the user seeking more accurate dose levels, please use the Utility and determine appropriate dose level for your particular metrics. Here is a "by the numbers" procedure:
1. Set meter reading in parameter 1.
2. Set hypothetical dose to same minutes as shown in parameter 1 sidebar.
3. Set parameter 2 skin type (note IU decrease as skin type increases)
4. Set % body (note IU increase as % body exposure increases above 10%)
5. Set SPF if any (note IU large decrease as SPF increases above 0)
6. Set % tan (note IU decrease as tan level increases)
7. Set age (note IU decrease above and below baseline 20yr old)