Sure but you should also be highly skeptical of people telling you that sunscreen is always required to go outside. A lot of the studies are funded by sunscreen companies which stand to make a lot of money.

> Tanning is a response to skin cell damage

I don't think this is true in any meaningful sense. Damage is part of life. Your body repairs minor damage and it is usually a good thing to trigger the repair pathways once in a while. This is also the basis for exercise - your muscles and tendons are damaged when you work out, but they get rebuilt stronger. Your DNA is also repaired, and turning repair pathways on can sometimes improve tissue quality/collagen production or get rid of imperfections - this is the basis of microneedling and cosmetic techniques, some of which involve light exposure. UV therapy is also a treatment for psoriasis (skin inflammation).

If any amount of sunlight is bad, ask yourself why melanoma typically occurs on the trunk region (in men) or legs (women) rather than say the face or arms. Those are regions that are normally hidden, but are then suddenly exposed when you go shirtless/at the beach.

The most dangerous thing is to go straight from non-exposure to high exposure. But if you gradually increase exposure, the body has many ways of dealing with non-overwhelming amounts of damage. Damage can in fact trigger repair which is often beneficial, as this article alludes to.

Most importantly, the more beneficial UV rays (UVB) for vitamin D production are weaker than the more harmful ones (UVA), so any sunscreen or glass that "blocks UV" necessarily blocks all UVB before you get close to blocking all UVA. Nothing can actually block 100% of UVA. But let's say you slather sunscreen on every time you go out. Now imagine one day you forget it or run out of it or for whatever emergency reason can't apply it. Now your pale unready skin is exposed to a large dose which could actually do more damage than your body is ready to repair.

The best time to get UVB is actually around solar noon. So, depending on your skin type, the best thing to do is to expose yourself to sunlight for short amounts of time (start with 1 minute if you want) without sunscreen before applying sunscreen. Then gradually increase the non-sunscreen time as your skin turns up repair pathways (and you get tanner).

> This is also the basis for exercise - your muscles and tendons are damaged when you work out, but they get rebuilt stronger

This is an outdated view, evidence shows muscle/tendon growth/adaptation occurs primarily via mechanical tension and metabolic stress, with damage playing a minimal or even counterproductive role. hypertrophy happens despite it, not because of it.

[The development of skeletal muscle hypertrophy through resistance training: the role of muscle damage and muscle protein synthesis. Schoenfeld et al., 2017](https://pubmed.ncbi.nlm.nih.gov/29282529/)

Solar noon sunlight microdose is now on my todo list for tomorrow, thanks.

Are you sure about this? I always heard about Australians (especially surfers) that had a high melanoma incidence and that it had made it clear that even if you are adapted (tanned) cancer risks still rises with exposure time.