Anyone that’s had a sunburn knows that the pain gets worse hours after the sun exposure. Why does it take so long for the body to feel the pain?
Because the redness and pain are actually part of your body’s reaction to the damage caused to your skin cells by UV rays. It takes a few hours before the healing process to rev up.
Further, what we call sunburn is inflammation and not a thermal burn.
Even acute radiation sickness (caused by ionizing radiation) does not kick in immediately.
Technically, sunburn is just that: shallow ionizing radiation tissue damage. (The difference between ultraviolet and gamma is just a few orders of magnitude of electromagnetic frequency.)