Photoprotection

Photoprotection comprises mechanisms that reduce damage from excessive or harmful light exposure, including energy dissipation, light avoidance, screening, and cellular repair.

Non-photochemical quenching: A set of processes that safely dissipate excess absorbed light energy as heat in photosynthetic organisms. It sheds surplus excitation energy before that energy generates damaging reactive oxygen species.
Sunscreen: A topical product that reduces ultraviolet radiation reaching the skin through absorption, reflection, or scattering. It is a direct, widely used intervention against solar ultraviolet exposure.
Ultraviolet: Electromagnetic radiation with wavelengths shorter than visible violet light and longer than X-rays. Ultraviolet radiation is a major source of harmful exposure addressed by photoprotection.
Phototaxis: Directional movement of an organism or cell in response to light. It changes position relative to light rather than reducing damage through shielding or repair.
Carotenoids: A family of pigments that absorb light and help protect cells from oxidative damage. They quench reactive oxygen species and contribute to energy dissipation in photosynthetic tissues.
Shade: An area shielded from direct sunlight by an object or structure. Reducing incident light lowers exposure without requiring a biological response.
Photosynthetically active radiation: The 400–700 nanometer wavelength range used by plants and other photosynthetic organisms for photosynthesis. Its useful energy can become hazardous when absorbed in excess.
Phototropism: Directional growth of a plant organ in response to light. It redirects growth toward or away from light instead of directly neutralizing light damage.
Melanin: A pigment in skin, hair, and eyes that absorbs ultraviolet and visible light and helps limit cellular damage. Its absorption and antioxidant activity help shield skin cells from radiation.
Sunglasses: Eyewear designed to reduce visible light and, in many designs, ultraviolet radiation reaching the eyes. They protect light-sensitive eye tissues by filtering incoming radiation.

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