Exposome extrinsic factors in the tropics: The need for skin protection beyond solar UV radiation

Abstract

Environmental factors such as solar ultraviolet radiation (UV), air pollution, and variations in the air temperature (T) and relative humidity (RH) affect skin health. However, it is still unclear what effects on the skin may occur as the result of these combined exposures. This study was designed to quantify environmental exposures during routine daily activities to provide quantitative metrics that inspire future studies on exposome and human health. Two bicyclists were equipped with instruments to collect specific data concerning UV (at different angles), T, RH, ground-level ozone (O3), and chemical exposures. Measurements were conducted in the summer and winter seasons of 2016–2017 in four touristic and urban Brazilian cities. Erythemal UV doses (EryD) exceeding the minimal erythemal doses (MED) for phototype V (EryD > 600 Jm−2) were registered in most tours, including cloudy weather and during the winter. Significant EryD were also observed in tilted body parts. Humidex Index (HI) higher than 30 °C revealed great thermal discomfort in most regions, mainly during the summer. O3 amounts were generally below the thresholds established by the World Health Organization (WHO), except for two instances in which the peak of O3 concentrations exceeded the 100 μg m−3. More than 10% of chemicals sampled during the tours were identified as Polycyclic Aromatic Hydrocarbons (PAH), including anthracene (peak of 207 ng per gram of air). There was a combination of EryD exceeding the MED, thermal discomfort, and PAH exposure in most studied areas. We concluded that this exposome could accelerate and amplify skin-related damages generally associated with a single environmental factor exposure, such as sunlight exposure at any time of the year, for example.