# Analysis of Research Hotspots and Trends in Confined-Space Work Safety Based on CiteSpace
## 4 Discussion  
### Analysis and Discussion of Research Hotspots  
According to bibliometric analysis and the existing literature, current research on confined-space work safety mainly focuses on safety management, accident investigation and analysis, emergency rescue, risk assessment, and gas detection technology. Numerical simulation is an important research method in this field, with scholars using it to simulate the flow field of harmful gases (such as methane and hydrogen sulfide) in confined spaces, as well as the internal flow field, temperature field, and the distribution of oxygen and carbon dioxide during ventilation [50,51]. The inherent characteristics of confined spaces contribute to the presence of multiple hazards, including poisoning, suffocation, falls, and drowning, which increase the risk of accidents [52]. With the release of the Safety Regulations, both academic institutions and enterprises have heightened their focus on confined-space work safety. Since 2006, \"safety management\" and \"preventive measures\" have been primary research topics, often combined with accident investigation, analysis, and risk assessment. Refined safety management schemes, such as access management, personnel training, safety supervision, and rescue plans, are formulated based on accident cause investigations and risk analyses using methods like extension models and edge computing [53,54,55,56,57]. Commonly used risk analysis methods mainly include fault tree analysis (FTA) [58], the fuzzy bow-tie methodology [59], and the analytic hierarchy process. Statistics indicate that more than 90% of major confined-space accidents involve blind rescues, leading to increased casualties, with approximately 50% of the victims being rescuers [60]. Consequently, emergency rescue has become a key research direction in China since 2013. Further research into emergency rescue has highlighted that poor ventilation and harmful gas accumulation in confined spaces are primary causes of rescuer casualties. As a result, increasing attention has been given to ventilation and detection in confined spaces, as well as the generation and distribution patterns of gases, to enhance rescue efficiency and ensure rescuer safety. The advancement of science and technology, along with the trend of disciplinary integration, has led to the application of advanced technologies such as artificial intelligence and big data in this field. Examples include designing robots for confined-space work, rescue, and detection [61,62,63,64], implementing intelligent supervision [65], and developing early warning and prevention systems [66]. Confined spaces include a wide range of environments, including the interiors of pressure vessels, tanks, cylinders, silos, pits, pipes, sewers, shafts, machinery, factories, and certain spaces on ships [52]. Traditional research has primarily focused on vertical shafts, sewage pipes, and heating pipelines in municipal engineering [15], as well as on storage tanks, sewage treatment facilities, and pressure vessels in industrial and trade enterprises [19,37]. In recent years, scholars have begun exploring new areas, such as power tunnels [54], highway tunnels [44], cabins [67], and barns [2]. With the frequent occurrence of confined-space accidents in chemical enterprises, research in this field has gradually become a significant hotspot. A summary of hotspots in the research on confined-space work is shown in Figure 14.  
In addition, the parameter selection for CiteSpace software, including thresholds and time slices, involves a degree of subjectivity. The evaluation of the mapping's satisfaction typically relies on parameters such as module value and average silhouette value. However, relying solely on these parameters may result in less comprehensive research [49]. At the same time, to enhance the accuracy of the literature database, it is sometimes challenging to ensure the comprehensiveness of the literature search, which may lead to certain limitations in the database.