The vitamin D window opens in 4 hours!

From 11:56 AM until 12:12 PM today, the sun will be high enough in the sky that its powerful actinic rays will reach the earth with enough energy for exposed skin to produce vitamin D.

Of course, the temperature around noon will be about 12℉, so I’m not expecting to have much exposed skin, but it is still nice to know that vitamin D production will be possible.

There might be an unseasonably warm and sunny day at any time this month or next, giving me a chance to make some vitamin D. And soon enough spring will come.

(Ephemeris data valid for where I live. The opening of the vitamin D window will likely be different for you.)

Deadly actinic rays

I shared a link to this article by Rowan Jacobsen, with the comment “This article falls so squarely in the sweet spot of reinforcing my own preconceptions, I almost hesitate to tweet it.” But I did, with a few brief quotes.

Freed of the limitations of twitter, here’s a more extended excerpt:

Lindqvist tracked the sunbathing habits of nearly 30,000 women in Sweden over 20 years. Originally, he was studying blood clots, which he found occurred less frequently in women who spent more time in the sun—and less frequently during the summer. Lindqvist looked at diabetes next. Sure enough, the sun worshippers had much lower rates. Melanoma? True, the sun worshippers had a higher incidence of it—but they were eight times less likely to die from it.

So Lindqvist decided to look at overall mortality rates, and the results were shocking. Over the 20 years of the study, sun avoiders were twice as likely to die as sun worshippers.

There are not many daily lifestyle choices that double your risk of dying. In a 2016 study published in the Journal of Internal Medicine, Lindqvist’s team put it in perspective: “Avoidance of sun exposure is a risk factor of a similar magnitude as smoking, in terms of life expectancy.”

Source: Is Sunscreen the New Margarine? | Outside Online

Jacobsen later mentions the app dminder, which I’ve been using for several years now. It helps you optimize your sun exposure (getting maximum vitamin D production without getting sunburned, based on time of year, time of day, location, and skin pigmentation). I just checked the app, which tells me that it’s just 8 days until the vitamin D window reopens here in Savoy, Illinois!

I concluded my little tweet storm with this: Pretty much every nice day of the spring, summer, and fall, I announce to my wife around midday that “I’m going out to expose my integument to the deadly actinic rays of the sun.” And then I do. I feel so much better since I started doing this.