Extended Abstract
Introduction
Despite significant advancements at the international level, few studies in Iran have comprehensively examined the environmental impacts of urban development based on Healthy City indicators. Many domestic studies have focused on the isolated analysis of components such as air pollution, waste management, or green spaces, while the systematic relationship of these components with the Healthy City framework has been neglected (Mohammadi et al., 2023; Rezaei & Sadeghi, 2019). This research gap is particularly noticeable in specific areas such as District 7 of Karaj, where population density, the shortage of open and green spaces, traffic-related pollution, and the presence of small-scale industrial units have subjected the environmental condition to numerous challenges.

The necessity of conducting this research arises from the fact that the precise identification and analysis of environmental indicators in accordance with Healthy City criteria can provide a scientific foundation for formulating urban management strategies and take an effective step toward enhancing the quality of life of citizens. This study aims to comprehensively assess the environmental impacts of urban development in District 7 of Karaj and align them with Healthy City indicators, seeking to propose a strategic framework that, while addressing current challenges, paves the way for sustainable development.

Methodology
This research is applied in nature and, methodologically, descriptive-correlational, conducted using a variance-based structural equation modeling approach. The statistical population consisted of 124,688 residents of District 7 of Karaj. Using Cochran's formula with a 95% confidence level, a sample size of 357 individuals was determined, and a stratified random sampling method proportionate to the population distribution across the district's neighborhoods was employed. The data collection instrument was a researcher-developed questionnaire designed based on environmental impact assessment indicators and the World Health Organization's Healthy City indicators. Content validity was evaluated through expert judgment, and construct validity was assessed via confirmatory factor analysis (CFA) using SmartPLS. For reliability, Cronbach's alpha and composite reliability were utilized. The conceptual model comprises the exogenous variables "Physical Environment (ENV_PHY)," "Environmental Infrastructure (ENV_INF)," and "Green Space (GREEN)," the mediating variable "Social Participation (SOC_PART)," and the primary endogenous variable "Urban Health (HEALTH)." The variable "Age (AGE)" was included as a control variable. Data analysis was performed using SmartPLS 4 software.
Results and Discussion
The results obtained from the structural equation modeling analysis using the PLS-SEM method indicated that the environmental impact assessment indicators of urban development in District 7 of Karaj, across four main dimensions—namely, the physical environment, infrastructural environment, green spaces, and social participation—have a significant effect on the dependent variable of urban health.

1. Physical Environment (ENV_PHY):
The factor loadings of the indicators of physical quality, roadway safety, and urban fabric organization were all above 0.7, and the path coefficient between this dimension and urban health was reported as β = … , which was significant at the 95% confidence level. This finding indicates that improving the physical quality of neighborhoods in the district exerts the greatest effect on enhancing residents' quality of life and sense of well-being.

2. Infrastructural Environment (ENV_INF):
The indicators of access to public services, transportation, waste management, and the water supply network exhibited composite reliability values above 0.8. The influence of this dimension on urban health was confirmed with a path coefficient of β = … . The results demonstrate that the upgrading of urban infrastructure constitutes a prerequisite for realizing Healthy City indicators in this region.

3. Green Spaces (GREEN):
Based on factor analysis, the indicators of per capita green space, equitable distribution, and maintenance quality of green spaces garnered the highest mean importance scores from the citizens' perspective. This dimension exerted a strong positive effect on urban health (β = …) and, in terms of effect size (f²), was ranked as "large."

4. Social Participation (SOC_PART):


This dimension played a mediating role between physical-infrastructural factors and urban health. The bootstrap test of indirect paths demonstrated that citizens' participation in local decision-making significantly enhances service satisfaction and fosters a sense of place attachment.

5. Impact of Control Variables (AGE):
Examining the role of citizens' age revealed that age groups above 50 years exhibit greater sensitivity toward infrastructure improvement and environmental safety, whereas younger individuals show more positive reactions to the quality of green spaces and cultural amenities.

6. Model Fit Indices:
The R² values for the urban health variable were equal to … , and the Q² values were positive, indicating the adequate predictive power of the model. The convergent validity indices (AVE > 0.5) and composite reliability (CR > 0.8) also attest to the high validity of the measurement instrument.

Conclusion
In sum, the findings suggest that the physical and infrastructural development of District 7 of Karaj, provided that simultaneous attention is paid to green spaces and the social participation of residents, can ensure both the improvement of urban environmental quality and the enhancement of urban health indicators. However, the physical discontinuity and dispersion of the existing neighborhoods constitute a serious obstacle to the functional integration of the district.
any technical or infrastructural intervention. Practically, this study recommends: (1) immediate reform of the institutional structure to unify decision-making centers; (2) formulation of a participatory strategic plan focused on environmental resilience, including a waste management master plan and a green-blue