Photoaging is defined as aging due to exposure to the sun. UVA light (longer wavelength, 320 to 340 nm) penetrates deeper into our skin to mess with the keratinocytes and dermal fibroblasts (these are cells that give skin its strength and resilience). It also acts to generate reactive oxygen species in our skin (like the superoxide anion, hydroxyl radicals, and peroxides), which can provoke DNA damage. UVA produces long term actinic damage (the photo-chemical effects of exposure to the sun) and melanin formation or tanning.

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