Environmental health inequalities (EHI), understood as differences in environmental health factors and in health outcomes caused by environmental conditions, are studied by a wide range of disciplines. This results in challenges to both synthesizing key knowledge domains of the field. This study aims to uncover the global research status and trends in EHI research, and to derive a conceptual framework for the underlying mechanisms of EHI. In total, 12,320 EHI publications were compiled from the Web of Science core collection from 1970 to 2020. Scientometric analysis was adopted to characterize the research activity, distribution, focus, and trends. Content analysis was conducted for the highlight work identified from network analysis. Keyword co-occurrence and cluster analysis were applied to identify the knowledge domain and develop the EHI framework. The results show that there has been a steady increase in numbers of EHI publications, active journals, and involved disciplines, countries, and institutions since the 2000s, with marked differences between countries in the number of published articles and active institutions. In the recent decade, environment-related disciplines have gained importance in addition to social and health sciences. This study proposes a framework to conceptualize the multi-facetted issues in EHI research referring to existing key concepts.

Insomnia is a prevalent sleep disorder that causes serious harm to individuals and society. It is closely linked to not only personal factors but also social, economic and other factors. This study explores the influencing factors and spatial differentiation of insomnia from the perspective of social media. This paper chose China's largest social media platform, Sina Weibo, as its data source. Then, based on the collected relevant data of 288 Chinese cities from 2013 to 2017, it explored the impact of economic, social, and environmental factors and an educated population on insomnia. Additionally, the importance and interaction of each influencing factor were analyzed. According to the results, the gross domestic product (GDP), proportion of households connected to the Internet and number of students in regular institutions of higher education are the major factors that influence insomnia, and their influences show obvious spatial nonstationarity. Rapid GDP growth has increased the probability of insomnia, and the positive correlation between the proportion of households connected to the internet and insomnia has strengthened annually. Although the impact of insomnia on college students decreased in some regions, the overall impact was still increasing annually, and spatial nonstationarity was obvious. Properly controlling GDP growth and unnecessary time spent online and guiding people to develop healthy Internet surfing habits and lifestyles will help improve their sleep quality. Our research results will help relevant professionals better understand the distribution of regional insomnia and provide a reference for related departments to formulate regional insomnia prevention and treatment policies.

A large proportion of Europeans are exposed to high levels of transportation noise, which can cause physiological and psychological stress, leading to negative health impacts. Few studies have examined the association between transportation noise and self-rated health (SRH), a summary indicator of morbidity. We aimed to assess the associations of SRH with both annual average road traffic noise exposure and nighttime transportation noise annoyance, examine geographic differences, evaluate potential effect modification and interaction by sex, and investigate whether annoyance mediates the relationship between road traffic noise and self-rated health. Using NAKO baseline data (n = 174,956), we implemented a cross-sectional study using logistic regression to analyze associations of road traffic noise ≥55 dB(A) Lden and nighttime transportation noise annoyance with poor SRH, adjusting for relevant sociodemographic characteristics and environmental co-exposures, including air pollution and greenness. We examined geographic differences, tested for effect modification and interaction by sex, and used path analysis to assess mediation by annoyance. Road traffic noise ≥55 dB(A) (OR 1.06, 95 % CI 1.01; 1.10), and moderate (OR 1.28, 1.23; 1.32) and strong nighttime transportation noise annoyance (OR 1.73, 1.65; 1.81) were associated with higher odds of poor SRH. Associations were similar for males and females, but varied across study regions. The path analysis revealed that road traffic noise was associated with higher odds of poor SRH indirectly via nighttime transportation noise annoyance (indirect effect). In our study, nighttime transportation noise annoyance was more strongly and consistently associated with poor SRH than road traffic noise. Reducing both transportation noise and related annoyance could help protect population health.