This study investigated the long-term exposure of residents in proximity to Municipal Solid Waste Incinerators (MSWIs) in Seoul, South Korea, to dioxins and heavy metals (lead, cadmium, and mercury), emphasizing environmental and public health implications. The researchers analyzed the temporal trends in blood concentrations of these contaminants, considering demographic factors such as age and gender, using data collected over six survey rounds from 2002 to 2021. The results revealed a significant decline in blood lead levels, particularly among females, with greater reductions in individuals with initially elevated blood lead levels. Cadmium concentrations remained relatively stable, whereas mercury levels exhibited minor fluctuations, with females demonstrating higher levels than males. Dioxins were slightly reduced, although their persistence in the environment and human bloodstream remains a concern. Age-specific analysis showed that younger women experienced the greatest decline in lead and dioxin levels. These findings highlight the efficacy of public health interventions in reducing environmental exposure, particularly among vulnerable populations, and underscore the need for continued monitoring and mitigation efforts to address the long-term environmental and health risks associated with exposure to these substances.