Yep, and a big difference even between the two sides of his face inside the truck! Hence why I don’t think indoor sunscreen is always necessary – the “nice” side of his face is pretty smooth despite the truck exposure.

Yeah,but there must be a diff between sitting indoors like in your house or at work 1-3m away from a window within the diffuse light area, than driving a truck all day with windows virtually up in your face exposed to both types of sunlight (direct + diffuse) and heat.

Diffuse UV isn’t different from direct UV in terms of what it is, it’s just the source of the UV. The general recommendation is that when the UV index is below 3, the combined direct and diffuse is low enough that it shouldn’t be a risk for cancer for a general population (it might be different if you have a photosensitivity condition or a family history). There’s less data on aging…

I always apply sunscreen to my face regardless – I figure the rest of my body will produce enough vitamin D!

At night I use a cleanser which contains glycolic and lactic acid. Do you recommend using sunscreen even when the uv index is below 3?

It can be if it’s intense (industrial ovens, for example) but sunscreen won’t help much there since it’s infrared radiation that’s the concern.

I would listen to the experts who have the most relevant expertise. For example, the last website doesn’t seem to be scientific; doctors aren’t physicists, so they may not be correct when it comes to how UVA travels through windows.