I've seen that claim given as "15 minutes of full body exposure to noonday sun", which is obviously quite different from what most of us might get. Also I expec

I've seen that claim given as "15 minutes of full body exposure to noonday sun", which is obviously quite different from what most of us might get. Also I expect it depends on your skin tone. If anyone could dig up the original source for the 15 minutes claim I would be curious (tried a bit but have to get back to work).