Comparing the ultraviolet index at sea level and altitude in six Chilean locations

This study examines the variability of the Ultraviolet Index (UVI) across different altitudes in Chile, analyzing simultaneous UVI measurements from six meteorological stations located at both sea level and high altitudes. The key findings include: UVI increases with altitude: In all regions studied, UVI levels were significantly higher at elevated locations than in coastal areas. For instance, UVI ratios between high and low-altitude sites ranged from 1.14 to 1.39, indicating up to 39% higher UV exposure at greater heights. High UVI values in risk categories: Alarmingly, more than 50% of the UVI measurements surpassed the high-risk threshold in several high-altitude areas. In the Atacama region, over 60% of UVI values exceeded 11, considered highly harmful. Altitude effect on UVI: The altitude effect (AE), calculated as the percentage increase in UVI per 1000 meters, ranged from 5.7% to 11.6%, with higher values in regions with more significant altitude differences. Discrepancies between modeled and measured UVI: The Tropospheric Ultraviolet and Visible (TUV) radiation model overestimated UVI values by 15–27% under clear-sky conditions, highlighting the influence of local factors like cloud cover, aerosols, and surface reflectance on UV exposure. These results underscore the urgent need for increased awareness of UV risks at high altitudes, particularly for those involved in outdoor activities in these regions. The study advocates for more robust public health initiatives to ensure adequate sun protection in high UV environments.