A global score for skin environmental exposure: integrating UV radiation, heat, and pollution via fuzzy analytic hierarchy process.

Environmental stressors such as ultraviolet radiation (UVR), air pollutants, and thermal stress interact synergistically to accelerate skin damage, yet most available indicators still assess these factors in isolation. The Skin Environmental Exposure Score (SEES) is a new and innovative fuzzy logic-based tool that integrates UVR, heat, ozone, and particulate matter into a single 0-1000 score, prioritizing UVR while quantitatively incorporating co‑exposures relevant to cutaneous health. The term “score” is deliberately adopted to emphasize a standardized, easily interpretable numerical outcome that facilitates communication with both scientific and non‑specialist audiences. Using local and global environmental datasets, SEES reveals that urban pollution markedly amplifies UVR-related risks and that heat stress can extend high-risk exposure windows beyond traditional midday peaks, including early morning and late afternoon periods. Distinct regional patterns emerge, with tropical areas experiencing persistent combined UVR-heat stress, while temperate regions are more strongly affected by pollution-driven risks. Based on these patterns, SEES supports evidence-based thresholds for sun-safety policies, including pollution-adjusted UV alerts, heat-adaptive photoprotection guidance, and identification of high-risk regions. For clinicians, SEES provides a practical, quantitative measure of the external skin exposome, directly linking climatic and pollution conditions to cutaneous risk and offering a more realistic basis for prevention counseling than UV or air-quality indices alone. This tool can inform skin cancer prevention, photoaging strategies, and the protection of vulnerable populations in routine clinical practice and public health campaigns. Future applications should extend SEES to long‑term climate scenarios to anticipate evolving patterns of environmental risk to the skin.