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Isn't that for adults though? My understanding is that kids tend to need much more vitamin d than adults (for growing bones).

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It's not really how much you need in terms of a volume, but just how long it takes to get to maximum blood concentrations. In direct sunlight in the summer you get to maximum concentrations very quickly, like <15 minutes timescale. And staying out in the sun longer doesn't raise levels further. So if you just semi-regularly get 30 minutes of sun (possibly less), the blood concentration will stay maxed out. (In other words, some sun every day or two might help, but 8 hours of exposure on one day does no more good than much less exposure would.)

You said exactly what I was trying to point out. I wouldn't put sunblock on my daughter or myself for <20min exposure. That just seems extreme. When I apply it, we're heading out for hours, or all day.

This also doesn't account for skin variances. We're extremely fair-skinned and burn easily. There is no way, even through clothing coverage, I would risk the possible burns that I've seen other children have.

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