Abstract: Sunlight’s ultraviolet (UV) radiation presents a double-edged phenomenon. While moderate exposure confers notable benefits, excessive UV exposure can induce skin damage and potentially lead to carcinogenesis. Sunscreen agents function as customized “molecular shields” for the skin, utilizing their distinctive physicochemical properties to establish a robust defensive barrier against UV radiation. This study systematically investigates the underlying chemical mechanisms of UV protection through comprehensive performance evaluations of both laboratory-formulated sunscreen emulsions and commercial products. Employing UV spectrophotometry, UV power meter, and UV indicating card across multiple assessment dimensions, we demonstrate the variations among different sunscreen agents and sun protection factor (SPF) values, successfully correlating protective efficacy with active components. This work further innovatively develops engaging experiments including UV visualization and hands-on sunscreen formulation, effectively translating complex photoprotection principles into accessible science popularization practices. This approach establishes a complete public education framework spanning from fundamental knowledge to practical protection strategies, seamlessly integrating UV protection awareness into daily life. Our work fosters scientific understanding of “photoprotection for photohealth”, enabling the public to safely enjoy sunlight while appreciating chemistry's remarkable contributions to modern living.

Key words: Sunlight, Ultraviolet, UV protection, Molecular shield, Science popularization