Standard shirts block virtually all ultraviolet radiation from the sun.
Tan-through shirts permit some UVA (tan) and UVB (vitamin D) radiation to get to the skin
Tan-through shirt appears to have an equivalent SPF = 2 in UVB spectra
Thus, the skin covered by a tan-thru shirt generates about 1/2 of the vitamin D than that of skin directly exposed to the sun
If you want to generate the same amount of vitamin D and have less UVB on each square inch on skin you can expose more skin to the UVB.
Maximizing the UVB/UVA ratio appears to
Reduce the damage to the skin
Increase the amount of vitamin D generated
UVB/UVA is maximized at solar noon +- 2 hours.
I (Henry Lahore, admin of VitaminDWiki) purchased a tan-through T shirt July 2013
Update March 2015 - own several "vitamin D" shirts
There are several companies making that type of shirt
I happened to buy mine from: http://www.tanthrough.com/index.htm
Relative number of minutes in sun
- 45 minutes long sleeved shirt +pants (11% skin)
- 20 minutes T shirt + pants (25% skin)
- 14 minutes T shirt + shorts (35% skin)
- 13 minutes Tan-through T shirt + pants (38% skin) = 25% + (26% trunk X 50% shirt)
tan-through T shirt provides about as much vitamin D as wearing shorts
- 10 minutes no shirt + pants (50% skin)
- 7 minutes no shirt,+ shorts (88% skin)
What I normally wear in the summer when mowing the lawn, shopping: Tan-thru T shirt + shorts = 75% skin
Note: The above does not indicate IU of vitamin D as the amount of time also varies with:
- standing up/lying down
- skin color
Of course, not wearing a shirt is often socially unacceptable for
- seniors, and many adults
- Golfing, playing baseball, gardening, walking in a park, bicycling, hiking, jogging, picnicking, etc.
Also, a tan-through shirt should keep you somewhat warmer in cooler temperatures.
Note: A standard T shirt has about 1/100 UVB vs tan-through has 1/2 UVB
Update June 2014 - bought a poloshirt which is tan thru
From their literature.
Microsol fabric is a gas infused polymer with 2X the surface area of standard fabric - allowing more wicking moisture
lets more of the tanning rays and less of the burning rays to pass thru
Found a 2008 patent application http://www.google.com/patents/WO2008129278A2?cl=en which specifically mentions use for burka. Apparently a patent was not awarded.
Many companies have tan-thru fabric on Alibaba
Perhaps I will get around to making a superman logo which I can occasionally attach to the shirt
See also VitaminDWiki
- Minutes in the Sun for 1000 IU default 30 degrees North
- Face 3.5%, neck 2%, trunk 26%, hands 6%, arms 14%, legs 14%, thighs 18%
- No – 10 minutes per day of sun-UVB is NOT enough
- Survey finds that Non-Caucasians do not feel that people need sun exposure – July 2012
- Hypothesis: Sun provides more than vitamin D – June 2012
- Whites were 2X more likely to be vitamin D deficient if wear long sleeves – Jan 2012
- Sunlight and Your Health: An EnLIGHTening Perspective - Holick Video Dec 2014
- UV decreases Multiple Sclerosis via cis-urocanic acid (and via vitamin D) – June 2013
- Business opportunity: you can now make stuff which only passes vitamin D wavelength - not Cooltan
- Overview Middle East and vitamin D
Cooltan type cloth would be great in Islamic areas which use concealing clothing
Short url = is.gd/cooltanD