The evolution of Industry 4.0 and the emerging paradigm of Industry 5.0 have introduced disruptive technologies that are reshaping modern manufacturing environments. Among these, Digital Twin (DT) and Industrial Metaverse (IM) technologies are increasingly recognized for their potential to enhance Occupational Health and Safety (OHS). However, a comprehensive understanding of how these technologies integrate to support OHS in manufacturing remains limited. This study systematically explores the transformative role of DT and IM in creating immersive, intelligent, and human-centric safety ecosystems. Following the PRISMA guidelines, a Systematic Literature Review (SLR) of 75 peer-reviewed studies from the SCOPUS and Web of Science databases was conducted. The review identifies key enabling technologies such as Virtual Reality (VR), Augmented Reality (AR), Extended Reality (XR), Internet of Things (IoT), Artificial Intelligence (AI), Cyber-Physical Systems (CPS), and Collaborative Robots (COBOTS), and highlights their applications in real-time monitoring, immersive safety training, and predictive hazard mitigation. A conceptual framework is proposed, illustrating a synergistic digital ecosystem that integrates predictive analytics, real-time monitoring, and immersive training to enhance the OHS. The findings highlight both the transformative benefits and the key adoption challenges of these technologies, including technical complexities, data security, privacy, ethical concerns, and organizational resistance. This study provides a foundational framework for future research and practical implementation in Industry 5.0.

Purpose: This study explores the integration of digital technologies, vehicle routing optimization and continuous improvement principles (Lean and Six Sigma) to collectively enhance transportation efficiency and reduce negative environmental impacts. It aims to clarify how these complementary approaches contribute to reducing greenhouse gas (GHG) emissions, fuel and energy consumption and routing inefficiencies. Design/methodology/approach: A systematic literature review (SLR) was performed, examining 87 resource materials from SCOPUS. The review synthesizes research on digital technologies, green vehicle routing and continuous improvement and identifies key performance indicators (KPIs) and critical factors associated with environmental sustainability and operational efficiency in transportation systems. Findings: The study develops an integrative conceptual framework that positions digital technologies as enablers of data availability, real-time visibility and predictive decision-making, vehicle routing optimization as the operational execution mechanism translating data into emission-reducing routing decisions, and continuous improvement, operationalized through Lean Six Sigma, as a sustaining mechanism that supports process stability and long-term environmental performance. Environmental KPIs such as fuel and energy consumption, emissions and route efficiency, link these elements and enable systematic performance monitoring. The findings suggest that integrating these components can reduce unnecessary trips, idle time and resource waste while improving operational efficiency and environmental outcomes. Research limitations/implications: The framework is conceptual and requires empirical validation across different transportation contexts. Practical implications: The framework supports practitioners and decision-makers in implementing targeted strategies to achieve both operational improvements and environmental sustainability goals. Originality/value: This research integrates digital transformation, continuous improvement (Lean and Six Sigma) and vehicle routing optimization into a unified framework for sustainable and green transportation, addressing a fragmented gap in previous research.