Interestingly the best time to go out is at solar noon, when the UVB/UVA ratio is higher. Just go for a shorter amount of time to compensate for the higher overall intensity.
My country, Spain, is famous for its beaches. Everyone native leaves the beach in the middle of the day and returns after lunch/siesta, when the rays are less intense.
Cool anecdote but as I said, in the middle of the day you should go for a shorter amount of time (starting with just a few minutes) to get ideal UVB exposure.
Tourists are an especially bad example since they often work indoors all year or come from less sunny countries, so the sudden sun exposure is doubly bad for them.
Spain is sunnier yet has lower melanoma incidence than Northern Europe..almost like moderate sun exposure is protective, or that going from a cloudy country to a sunny area for a few weeks is especially bad - you can analyze it how you wish.
For sure that contributes to their higher ceiling for exposure, and also makes it harder for them to get vitamin D, which is why they shouldn't avoid going to the beach until the sun is down, since as a population they are quite deficient in Vitamin D.
I agree, but you can titrate your exposure. So at the beginning of the season, in the 12-3 window you can start by going 5 mins without sunscreen for a few days, then 10 mins, then 20 etc. depending on your skin type.
The worst thing to do is to go from low exposure (i.e. winter months, or just constant indoor time) to long periods of exposure, even with sunscreen.
No, UVA is stronger and more harmful. UVA penetrates deeper in the skin, since it's stronger. UVB stimulates Vitamin D production, while UVA doesn't.
So almost anything that is "UV-blocking" (sunscreen, UV-treated glass) gets rid of all of the beneficial UVB before UVA starts getting reduced. So you are actually enriching your exposure to the most harmful UV type, and not making Vitamin D.
This might explain the paradoxical finding that people who use sunscreen more can have higher rates of skin cancer
People who spend more time outdoors are more likely to try to wear sunscreen, as are people who already got a lot of pre-existing risk to excessive sun exposure.
Key word on try as its greatly assuming there isnt a wide audience who do use sunscreen, then just apply it in poor amount, or never re-apply but enjoy staying out far longer than most do in the sun feeling they're oh so very protected.
Spray sunscreens for example are just about useless, as are those solid stick applicators. They only get a fraction the amount you need for the rated protection. The biggest issue with sunscreen relates to companies selling sub par "convenience" slop, often right beside their other products some of which might actually be half decent.
Sure that’s a theory, but hasn’t been proven. If I recall, the study showed that heavy sunscreen use amongst sunscreen users was associated with higher cancer rates.
Secondly, if sun exposure is really that bad then how do you explain why most skin cancers are on the trunk and thighs rather than more exposed areas like hands and arms?
The simplest answer is it’s not sun exposure that’s bad but sudden high exposure after non-exposure (repair mechanisms can’t keep up with damage).
Not sure why I’m being downvoted. I guess there’s a lot of sheep among us. If anything I said is incorrect, please show me the evidence.
A critical factor for doing a screening is how many bad burns you've had on the chest and back which would probably be similar to many times the burns on the arms in terms of surface area x added probability.
Unfortunately, that I know of there are not many studies that compare 'frequent low/moderate exposure followed by high exposure' vs 'very low exposure (high sunscreen use) followed by high exposure'
These results show the specificity of the positive association between melanoma risk and intermittent sun exposure, in contrast to a reduced risk with high levels of occupational exposure.
Both the low-intermittent (HR = 1.26; 95%CI = 1.17–1.38) and high exposure groups (HR = 1.13; 95%CI = 1.01–1.26) had higher rates of melanoma than indoor workers.
The low-intermittent exposure group had elevated melanoma rates on the arms and trunk (body), while the high exposure group had an elevated rate on the head and trunk.
Digging into the data, the moderate exposure group had no detectable increase at any body site and a weak suggestion of lower risk (not statistically significant):
Why would the low-exposure group have a higher rate on the arms and trunk? Could it be because when they do go to the pool/beach, their arms are not protected? Whereas in the high exposure group, their arms are protected due to everyday exposure, but their trunk is only exposed when they go to the pool? Then again, you would think the low-exposure group would also have high trunk incidence, so there might be some confounding factors like ethnicity/behavior/dress.
Anyway, hopefully I convinced you that it's not as simple as more sun = always bad.
Tourists stay and get burn to a crisp