Effects of outdoor air pollution on the cardiovascular health of school-aged children residing near polluted areas and the efficacy of mitigation measures in Dar es Salaam, Tanzania

Abstract

Outdoor air pollution is a major global health threat, particularly for children in rapidly urbanizing low- and middle-income countries. While its respiratory effects are well-documented, evidence on cardiovascular impacts in children remains limited, especially in sub-Saharan Africa. This study assessed the effects of outdoor air pollution on the cardiovascular health of school-aged children residing near polluted areas in Dar es Salaam, Tanzania, and evaluated community awareness and perceived effectiveness of existing mitigation measures. A community-based cross-sectional study was conducted from December 2024 to July 2025 among 653 school-aged children living in areas classified as highly polluted based on proximity to industrial zones, major roads, and waste-burning sites. Data were collected using interviewer-administered questionnaires, and blood pressure was measured once using oscillometric devices. Log-binomial regression was used to identify factors associated with cardiovascular symptoms. The prevalence of elevated blood pressure among participants was 19.9%. Children with a history of respiratory disease had a significantly higher adjusted risk of cardiovascular symptoms (ARR = 8.81; 95% CI: 6.12, 12.67). Awareness of government mitigation measures varied: 71.5% were aware of waste management policies, while only 44.5% knew of vehicle emission standards. Although 61% of households reported using natural gas for cooking, less than half (45%) of participants perceived government measures as effective in reducing air pollution. Outdoor air pollution is associated with a considerable burden of cardiovascular conditions, including hypertension, among school-aged children in Dar es Salaam. Respiratory disease history significantly elevates cardiovascular risk. Despite moderate uptake of some clean energy interventions, public perception of policy effectiveness remains low, highlighting the need for stronger enforcement, community engagement, and integrated child health surveillance in polluted urban areas.