This paper aims to analyze the effects of physical activity, screen time, and academic burden on adolescent health in China and compare their effects by using the nationally representative sample data from the CEPS (China Educational Panel Survey) cross-section data. This paper first uses regression analysis to examine the relationship between physical activity, screen time, academic burden and health among Chinese adolescents. Then, this paper uses the clustering analysis the influence of physical activity, screen time, and academic burden on the health of Chinese adolescents. The empirical results show that: (1) along with exercise, helping with the housework also has a clear health-promoting effect on adolescents; (2) the time spent surfing the Internet or playing video games, and heavy studying or homework off campus have a negative effect on adolescents’ self-rated health and mental health; (3) physical activity has the greatest impact on self-rated health, while screen time has the greatest impact on mental health, and academic burden is not the most important factor affecting adolescent health in China.

In China, winning the battle for blue skies is a focal point of the central government’s environmental governance efforts. Public evaluations provide validity and legitimacy to the Chinese government’s top-level design for environmental governance. This study utilizes data from two waves of the Chinese General Social Survey (CGSS) conducted in 2013 and 2021, paired with objective air quality data, to conduct a longitudinal analysis of public evaluation of central government environmental governance in China. Furthermore, it explores the relationships between perceived air pollution, objective air quality, environmental knowledge, and public assessment of central government environmental performance. The findings indicate the following: (1) Over the past decade, there has been a noticeable improvement in air quality in China, leading to a significant enhancement in public perception of the central government’s environmental performance. (2) Subjective perceptions of air pollution have a significant negative impact on evaluations of the central government, whereas objective environmental governance measures do not exhibit significant effects. (3) Environmental knowledge plays a negative moderating role in the relationship between perceived air pollution and public assessment of central government environmental performance; individuals with higher levels of environmental knowledge tend to express greater dissatisfaction with the central government’s environmental performance upon perceiving air pollution. These research findings offer valuable insights for informing the formulation of environmental governance policies by the central government of China and provide lessons for other developing and highly polluting countries.

Background: The association between internet use and the mental health of older adults presents a complex research issue with inconsistent findings. While potential mechanisms have been explored, the integrated examination of socio-cognitive and health-behavioral pathways, particularly the chained mediation effect, remains understudied. Methods: Utilizing cross-sectional data from the 2023 China General Social Survey (CGSS), this study analyzed a sample of 3,206 adults aged 60 and above. Mental health was operationalized using a single-item measure of the frequency of depressive moods. A structural equation model (SEM) was employed to explore the parallel and chained mediating roles of perceived social justice and physical activity in the relationship between internet use and mental health. It should be acknowledged that these mediation analyses are statistical and exploratory in nature, and do not establish temporal or causal ordering. Robustness checks were conducted using propensity score matching (PSM). Results: Internet use was significantly and directly associated with better mental health ( β = 0.098, p < 0.001). Parallel mediation analysis revealed two significant but opposing indirect paths: a negative indirect effect through reduced perceived social justice ( β = −0.017, p < 0.001) and a positive indirect effect through increased physical activity ( β = 0.027, p < 0.001). Crucially, a significant chained mediation pathway was identified: internet use → lower perceived social justice → reduced physical activity → poorer mental health ( β = −0.018, p < 0.001). Multi-group analysis confirmed significant gender differences in these mediating pathways. Conclusion: Internet use is associated with older adults’ mental health through a complex mechanism involving both a direct positive association and indirect pathways via perceived social justice and physical activity. The verified chained mediation effect suggests a potential “cognition-behavior” transmission pathway. A key limitation of this study is its cross-sectional design, which precludes causal inference. These findings highlight the dual-edged nature of internet use, suggesting that public health initiatives aimed at promoting digital inclusion for aging populations could concurrently foster a positive online information environment, enhance digital literacy, and encourage physical activity to maximize benefits and mitigate risks.