Short-Term Associations Between Ambient Air Pollution and Outpatient and Emergency Visits for Hypertension: A DLNM-Based Time-Series Analysis in Baise, Guangxi, China

Mengdong Xin, Jiancheng Liang, Mingmei Shang, Rui Guo, Shusong Deng, Xiaoxiao Wei School of Public Health, Youjiang Medical University for Nationalities, Baise, Guangxi, People’s Republic of ChinaCorrespondence: Jiancheng Liang, School of Public Health, Youjiang Medical University of Nationalities, No. 98 Chengxiang Road, Youjiang District, Baise, Guangxi, 533000, People’s Republic of China, Email 2961102720@qq.comBackground: Despite growing evidence that short-term ambient air pollution increases hypertension risk, data from China’s border regions are limited; this study quantifies the association between daily pollutant concentrations and daily emergency and outpatient visits for hypertension in Baise, a southern border city.Methods: We collected hypertension case data from two tertiary hospitals in Baise City (1 Jan 2020– 30 Dec 2022) and concurrent local air pollutant and meteorological data, and used a distributed lag non-linear model (DLNM) to assess pollutant effects on outpatient and emergency visits, with subgroup analyses by sex, age, and season.Results: Every 10 μg/m3 increase in PM2.5 (lag06), PM10 (lag06), NO2 (lag06), and every 100 μg/m3 increase in CO (lag04), the risk of hypertension outpatient/emergency department visits increased by 3.2%, 2.8%, 14.8%, and 3.0%, respectively. Exposure–response curves were approximately linear without a clear threshold. There was no statistically significant effect modification by sex or age, whereas associations were stronger in the cold season than in the warm season.Conclusion: Short-term exposure to pollutants such as PM2.5, PM10, NO2, and CO is significantly associated with increased outpatient and emergency visits for hypertension, exhibiting a lag effect. During cold seasons, sensitivity to environmental pollutants among hypertensive patients markedly increases.Keywords: air pollutants, DLNM, relative risk, hypertension outpatient and emergency visits