0979 Associations of Solar Radiation with Cardiovascular Health among Black Adults

Abstract Introduction Black American adults bear a disproportionate burden of hypertension and cardiovascular risk. Beyond traditional clinical and behavioral factors, environmental exposures may cause cardiovascular stress. Since solar radiation contributes to daytime thermal load and can influence vascular tone and autonomic regulation, patterns of sunlight and cloud cover may shape cardiovascular pathways relevant to sleep. We examined whether recent daytime solar exposure was associated with resting blood pressure in a cohort of Black American adults. Methods We analyzed data from 198 Black American adults (122 females, 76 males; mean age 50.7±14.1 years) from two NIH-funded studies ‘ESSENTIAL’ and ‘MOSAIC’. Clinically measured systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were treated as continuous outcomes. Daily solar exposures from the satellite-based NASA POWER project were linked to residential coordinates, focusing on indices that distinguished clearer, direct sunlit exposures from cloudier, more attenuated exposures. Specifically, we examined direct-beam sunlight, diffuse radiation, the direct-to-diffuse radiation ratio, and cloud cover. These solar parameters were averaged over the seven days preceding clinic visits to characterize recent daytime exposure. Linear regression models, adjusted for age, sex, sociodemographic factors, and BMI, examined associations between solar measures and each blood pressure outcome. Results Clearer, direct sunlit weeks were associated with higher resting DBP and MAP. Higher direct-beam sunlight and direct-to-diffuse ratios were associated with higher DBP and MAP (all p≤0.04; model R²=0.17–0.20). In contrast, patterns indicating stronger cloud influence—greater cloud cover, and diffuse radiation—were associated with lower DBP and MAP (all p≤0.03; model R²=0.16–0.19). Corresponding associations with SBP were weaker and did not reach statistical significance. Conclusion In this cohort of Black American adults, daytime solar exposures were related to cardiovascular health, indexed by resting blood pressure. Clearer, direct sunlit environments were associated with higher diastolic and mean arterial pressure, whereas cloudier, more attenuated exposures were related to lower levels. These findings support a thermal pathway linking daytime solar exposure to vascular regulation and highlight the daytime environment as relevant for sleep-related cardiovascular disparities. Support (if any) NIH (R01HL142066 and R01AG067523).