Urban Health Inequalities and Healthy Life Expectancy: A Systematic Review of Social, Environmental, and Behavioral Risks

Background Metropolitan areas have become the focal point of both opportunities and inequalities because of the global transformation of demographic and health environments by accelerated urbanization. Urban living improves healthcare accessibility; however, it worsens inequalities in illness, multiple medical conditions, and healthy life expectancy (HALE), particularly among socioeconomically disadvantaged communities. The current body of research has divided risk assessment by emphasizing individual exposures or diseases, consequently disregarding the long-term consequences of urban hazards that are on the rise. Objectives This systematic study examines the convergence between traditional and contemporary urban health risk indicators and their role in the continuation of health inequalities throughout one's life expectancy. It evaluates the interaction between these risks and demographic changes, notably the aging of the population, and identifies research and policy gaps in addressing inequalities. Methods In accordance with PRISMA and Joanna Briggs Institute recommendations, we conducted a search of MEDLINE, Embase, Scopus, and Web of Science for papers published from 2000 to 2024. Eligible papers included peer-reviewed qualitative, interventional, systematic, and meta-analytic methods evaluating medical outcomes in global urban areas. A total of 5,642 records were evaluated; 142 research met the inclusion criteria. Thematic synthesis of the narrative grouped results into conventional risk variables, developing social and environmental circumstances, and demographic interactions. Results Urban health issues are influenced by both existing hazards, such as obesity, physical inactivity, tobacco, and alcohol use, and recent developments, including air pollution, noise, sleep disturbances, extreme temperatures, and endocrine-disrupting substances. Meta-analyses demonstrated that a 7% increase in mortality from all causes was associated with every 10 µg/m³ increase in PM₂.₅, with a disproportionate effect on low-income populations. In communities that were simultaneously confronted with stressful circumstances and socioeconomic challenges, the incidence of multiple medical conditions increased by 18–25%. In numerous instances, marginalized populations experienced a 5–10-year reduction in healthy life expectancy when contrasted with their wealthier counterparts. The quality of the evidence was moderate to excellent; however, research from societies with low or middle incomes was inadequately represented, and intervention studies were scarce. Conclusions Health inequalities in urban areas result from the interaction of behavioral, environmental, and structural factors. Urban health disparities cannot be attributed only to individual lifestyle decisions; rather, they are deeply rooted in governance, facilities and environmental frameworks. Addressing these issues requires comprehensive multisectoral initiatives, including air quality control, fair access to green and recreation places, resilient to climate planning, and enhanced regulation of both alcohol and tobacco settings. Future research must emphasize underrepresented areas, standardize multiple medical conditions measurements, and enhance causal and intervention-based studies to guide policy.