# Analysis of Research Hotspots and Trends in Confined-Space Work Safety Based on CiteSpace
## 1 Introduction  
Confined-space work poses significant risks across various industries and locations. Many potential hazards exist in confined spaces. The main ones are atmospheric (e.g., poisoning, asphyxiation, explosion), biological, and physical (e.g., mechanical, electrical, engulfment, falls, lighting, outside traffic) [1, 2]. Thus, work safety has become an important research topic in the field of global safety production [3]. Accidents in confined spaces can be traced back to 1812 in England, where a tombstone at a church graveyard recorded that three men lost their lives when they climbed down into a well and were overcome by the atmospheric conditions [2, 4]. To prevent accidents in confined spaces, countries have begun to formulate regulations and standards. As early as 1979, the National Institute for Occupational Safety and Health (NIOSH) published a criteria document providing recommendations for working in confined spaces [5]. In 1993, the Occupational Safety andHealth Administration (OSHA) regulation titled \"Permit Required Confined Spaces\" was published. Starting from the 1980s, a large amount of accident statistical analysis work has been carried out in countries such as the United States [6]. During 1997-2011, countries such as the United Kingdom, Canada, Singapore, and Australia also formulated regulations to regulate confined-space work [7; 8; 9; 10]. These regulations and standards have a certain effect on preventing accidents. However, rapid economic growth and the acceleration of industrialization and urbanization have led to a substantial increase in the number and frequency of operations in confined spaces, including inspection wells, sewage pools, pipe trenches, tanks, and reactors. This surge has highlighted the growing importance of addressing confined-space work safety. From 2016 to May 2021, China experienced an average of 207 major confined-space work accidents annually, resulting in 733 fatalities each year [11]. According to data from the Beijing Emergency Management Bureau, in Beijing alone, between 2006 and 2023, there were 85 confined-space work accidents, causing 147 deaths. In comparison, the mortality rates for every 100,000 workers engaged in confined-space work were 0.08 in Singapore, 0.07 in the United States, 0.05 in Australia, and 0.07 in Quebec, Canada [12]. Confined-space work accidents constitute a significant proportion of production safety incidents. Scientific research has always been the foundation for promoting the development of confined-space work safety. The literature on confined-space work safety in the WoS database dates back to 1966 [13], while related publications in the CNKI began appearing in 1985 [14]. Subsequently, scholars at home and abroad began to focus on various aspects of confined-space work, including risk factors, emergency rescue, safety management, and accident prevention. In China, [PERSON] et al. [15; 16; 17] tested and analyzed gases in municipal pipes and assessed their hazards, comparing and analyzing related concepts [18] and safety regulations [3] of confined-space work at home and abroad. [PERSON] et al. [19; 20; 21] examined the status and risks of confined-space work in industrial and trade enterprises. [PERSON] et al. [22] developed a real-time non-invasive monitoring and early warning device for assessing the physiological status of workers using physiological parameters as evaluation indicators. [PERSON] et al. [23] proposed a five-step analysis method for confined-space work, while [PERSON], [PERSON] et al. [24] summarized automated equipment for such environments. Despite these efforts, there is still a lack of comprehensive studies on confined-space work both in China and abroad. Researchers are unclear about the main research areas and emerging trends in this field, making it difficult to determine appropriate research directions. Therefore, it is necessary to review and analyze the existing literature on confined-space work safety to identify research hotspots and future trends.