Eli5; Would you get the same level sunburned if you were in the sun for 4 hours continuously as if you were the sun with the same intensity for 4 hours collectively with 10 minute shaded breaks?

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The breaks won’t help you. So I think the confusion here is because is that sunburn *isn’t* about temperature, so your skin doesn’t benefit at all if you “allow the skin to cool”. It’s about the UV rays hitting and damaging your skin and that damage will kick in in as little as 10 minutes in the sun. So unless your breaks means you are outside for a total of 4 hours over several days it makes no difference.


The breaks will technically help but incredibly little unless they’re hours long not minutes.. The damage isn’t a “heat burn” from your skin getting too hot. It’s a *radiation* burn caused by the sun’s UV rays. The damage from each ray happens instantly as each one hits you, goes into a skin cell, and smashes into some molecules inside and blows them up. Repairing this damage takes much longer than 10 minutes (sunburns last days) so you’re not going to get any meaningful recovery from 10 minute breaks. A comparison that might help explain to the kid: Let’s say instead of 4 hours of sun exposure, you’re going to get punched 20 times. Question: Would it be better to be punched 20 times in a row, or punched 20 times collectively but with a 5 minute break between every 5 punches? Answer: It makes very little difference, because you’re not going to get meaningful healing done in 5 minutes compared to the damage. And the first punch back from a break is going to do exactly as much damage as all the other punches.


Sunburns aren’t caused by the “heat” of the sun, they’re caused by direct genetic damage from the ultraviolet light. The “burn” you receive when you get a sunburn is actually caused when skin cells too damaged to continue functioning go through apoptosis (a fancy word for cell suicide) so they can be shed off and replaced. Your body has natural responses to reverse, fix or prevent further similar genetic damage from happening such as genetic repair an melanin production but my understanding is(not an expert) that those responses take time in the realm of hours to days to start fully triggering. If short 10 minute breaks do help it’s such a small amount that it’s probably immeasurable. Edit:spelling


I agree with the answers. Damage is more or less instant as soon as you’re exposed to UV light. There may be an anecdotal difference. Say you’re out from 2 pm until 6 pm. Four hours straight will result in a lot of UV. If you’re 10 minutes in the sun and 10 minutes in the shade, you would only have 2 hours of sun exposure. In order for the 4-hours to be comparable, you would have to be out from 10 am to 6 pm. Then there’s difference on the uv index at various hours, which may make those last few hours at dusk be less damaging than at noon.


People would take sunburns much more seriously if we called them what we should…radiation burns.