why doesn’t sunburn appear until hours after you’ve left the sun?

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why doesn’t sunburn appear until hours after you’ve left the sun?

In: Biology

Sunburn is a type of radiation burn caused by exposure to the sun. To put it simply, the radiation from the sun has bombarded the atoms that make up your DNA, causing irreparable damage. These cells with damaged DNA can no longer self-replicate, meaning they must be shed and replaced.

Like any burn, your body responds with inflammation of the affected area. This is the redness we typically associate with sunburn. What is happening is your body’s immune system has recognized that there is a region of localized damage to your skin, and has begun to repair that damage by replacing the skin in that area with new cells.

To do this, it increases bloodflow to the damaged area in order to supply more oxygen to help with the ‘repairs’. Depending on how *deep* the damage is, the more extreme the immune response will be (i.e. first, second, or third-degree burns).

Redness can appear within an hour of exposure, but typically you’ll experience the most pain between 6-48 hours. The pain and redness you feel is actually your body’s response to the sunburn, and will take several hours to fully peak.

You see. It is because there is a delayed inflammation in the skin that is due to the UV-radiation destroying cells and DNA. The inflammation takes some time to set in. The sun radiates 3.6 Watt per square meter at the surface of the Earth, which isn’t that high nor that low, and not enough to cause an instant reaction. However if the sun was radiating, let’s say 15000 Watt per square meter, we would get sunburned really fast since that reaction in the skin would speed up a lot.

Wait so can we clarify something here? I always get like number 2 or 4 sun tan oil because i want to tan, but i read that even spf 15-30 you will still get a tan but less harmful effects. Is this true? Do you just get less tanned? I thought it just blocks off everything so you dont even tan and it protects you from everything.

Have you never fallen asleep in the sun for hours? It doesn’t only show up after you are out of the sun. you just need to spend more time in the sun to notice the burning while it’s happening.

The short answer is, it doesn’t. Stay in the sun long enough and you will burn even without leaving the sun. Mostly you eyes are used to the bright light, so light hue differences aren’t so noticeable. Then when your eyes adjust back and some time has gone by you look and yourself and go “HOLY GOD!”.