Perceived Environmental Injustice and Mental Well-Being in Southern Nigeria: A Cross-Sectional Structural Equation Model of Environmental Engagement, Resilience, and Ecological Literacy

Background: Environmental degradation in Southern Nigeria exposes many communities to pollution, flooding, deforestation, and related ecological stressors, yet the psychosocial links between perceived environmental injustice and mental well-being remain insufficiently examined in African settings. This study investigated the associations among perceived environmental injustice, environmental engagement, resilience, ecological literacy, and mental well-being within a cross-sectional structural model. Methods: A cross-sectional quantitative study was conducted among 2009 adults recruited from selected communities in Southern Nigeria using a multistage, purposive sampling approach. Participants completed measures of mental well-being (WHO-5), perceived environmental injustice, environmental engagement, resilience (CD-RISC-10), ecological literacy, and sociodemographic characteristics. Confirmatory factor analysis and structural equation modelling were conducted in SmartPLS 4. Direct, indirect, and conditional indirect associations were estimated using 5000 bootstrap resamples. Results: Perceived environmental injustice was negatively associated with mental well-being (β = −0.31, p < 0.001) and with environmental engagement in the adjusted structural model (β = −0.19, p < 0.001). Environmental engagement was positively associated with mental well-being (β = 0.39, p < 0.001). The cross-sectional indirect association through environmental engagement was significant (β = −0.07, p < 0.001). The index of the conditional indirect association involving resilience was significant (β = −0.01, p < 0.001), with the negative indirect association stronger at lower resilience levels. In contrast, the index involving ecological literacy was not statistically significant (β = −0.00, p = 0.15). Conclusions/Recommendations: Perceived environmental injustice was associated with poorer mental well-being, while environmental engagement and resilience were relevant to the observed cross-sectional pattern. Responses to environmentally burdened communities should combine environmental governance and remediation with community engagement and psychosocial support. Longitudinal and qualitative research is needed to clarify temporal direction and contextual mechanisms.