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Sweat secretion and evaporation from the skin dictate the human ability to thermoregulate and thermal comfort in hot environments and impact skin interactions with cosmetics, textiles and wearable electronics/sensors. However, sweating has mostly been investigated using macroscopic physiological methods, leaving micro-to-macroscale sweating dynamics unexplored. We explore these processes by using a coupled micro-imaging and transport measurement approach used in engineering studies of phase change processes. Specifically, we used a comprehensive set of ‘macroscale’ physiological measurements (ventilated capsule sweat rate (SR), galvanic skin conductance and dielectric epidermis hydration) complemented by three microscale imaging techniques (visible light, midwave infrared and optical coherence tomography imaging). Inspired by industrial jet cooling devices, we also explore an ‘air jet’ (versus cylindrical) capsule for measuring SR. To enable near-simultaneous application of these methods, we studied forehead sweating dynamics of six supine subjects undergoing passive heating, cooling and secondary heating. The relative dynamics of the physiological measurements agree with prior observations and can be explained using imaged microscale sweating dynamics. This comprehensive study provides new insights into the biophysical dynamics of sweating onset and following cyclic porewise, transition and filmwise sweating modes and highlights the roles of stratum corneum hydration, salt deposits and microscale hair. 

Abstract The purpose of this investigation was to characterize factors that predict tap water mistrust among Phoenix, Arizona Latinx adults. Participants (n = 492, 28 ± 7 years, 37.4% female) completed water security experience-based scales and an Adapted Survey of Water Issues in Arizona. Binary logistic regression determined odds ratios (OR) with 95% confidence intervals (95% CI) for the odds of perceiving tap water to be unsafe. Of all participants, 51.2% perceived their tap water to be unsafe. The odds of mistrusting tap water were significantly greater for each additional favorable perception of bottled compared to tap water (e.g., tastes/smells better; OR = 1.94, 95% CI = 1.50, 2.50), negative home tap water experience (e.g., hard water mineral deposits and rusty color; OR = 1.32, 95% CI = 1.12, 1.56), use of alternatives to home tap water (OR = 1.25, 95% CI = 1.04, 1.51), and with decreased water quality and acceptability (OR = 1.21, 95% CI = 1.01, 1.45; P < 0.05). The odds of mistrusting tap water were significantly lower for those whose primary source of drinking water is the public supply (municipal) (OR = 0.07, 95% CI = 0.01, 0.63) and with decreased water access (OR = 0.56, 95% CI = 0.48, 0.66; P < 0.05). Latinx mistrust of tap water appears to be associated with organoleptic perceptions and reliance on alternatives to the home drinking water system. 

Abstract U.S. border colonias are peri-urban settlements along the U.S.–Mexico border. Residents often face substandard housing, inadequate septic and sewer systems, and unsafe or inadequate household water. As of 2015, an estimated 30% of over 5 million U.S. colonia residents lacked access to clean drinking water, suggesting health complications. This scoping review identifies a very limited existing set of research on water and sanitation insecurity in U.S.–Mexico border colonias, and suggests value in additional focused research in this specific context to address health challenges. Preliminary health data indicates that due to water insecurity, colonia residents are more likely to contract gastrointestinal diseases, be exposed to carcinogenic compounds from contaminated water, and experience psychosocial distress. These widespread health issues in colonias are exacerbated by historical and ongoing socioenvironmental injustices in the U.S.–Mexico border region and their relation to the poor health outcomes.