Despite the prevalence of the phenomena of peer victimization and bystander behaviors, little data has generated to describe their relationships and risk factors. In this paper, a self-administered survey using a cross-sectional cluster-random sampling method in a sample of 5450 participants (2734 girls and 2716 boys) between 4th and 11th grades was conducted at six schools (two primary schools and four middle schools) located in Shantou, China. Self-reported peer victimization, bystander behaviors and information regarding parents’ risky behaviors and individual behavioral factors were collected. Multinomial logistic regression analysis was applied to evaluate risk factors affecting peer victimization and bystander behaviors. The results indicated that urban participants were more likely to become bullying victims but less likely to become passive bystanders. Contrarily, bullying victimization was related to the increasing of passive bystander behaviors. Father drinking and mother smoking as independent factors were risk factors for peer victimization. Participants who were smoking or drinking had a tendency to be involved in both peer victimization and passive bystander behaviors. This study suggested that bystander behaviors, victims’ and parents’ educations play a more important role in peer victimization than previously thought.

Background: Current epidemiological evidence on the association between air pollutants and non-accidental mortality remains limited, particularly in developing countries. This study aimed to investigate the short-term association between ambient air pollution and non-accidental mortality, and to quantify the attributable disease burden in Shantou, a subtropical coastal city in China. Methods: Daily data on non-accidental mortality, meteorological factors, and ambient air pollutants including PM _2.5 , PM ₁₀ , SO ₂ , NO ₂ , CO, and O ₃ were collected in Shantou from 2016 to 2020. A Poisson generalized additive model (GAM) was applied to estimate the acute effects of air pollutants on non-accidental mortality, with stratification analyses by gender, age, and season. Attributable fractions (AFs) and attributable numbers (ANs) were further estimated based on the World Health Organization (WHO) air quality guidelines and Chinese air quality standards. Results: Non-accidental mortality in Shantou was significantly associated with exposure to PM _2.5 , PM ₁₀ , SO ₂ , NO ₂ and O ₃ , but not with CO. Per 10 μg/m ³ increase in air pollutant concentration, the strongest relative risks (RRs) and 95% confidence intervals (CIs) for non-accidental mortality were 1.0199 (1.0106–1.0294) for PM _2.5 at lag03 days, 1.0146 (1.0085–1.0209) for PM ₁₀ at lag 03 days, 1.1268 (1.0773–1.1786) for SO ₂ at lag 07 days, 1.0256 (1.0093–1.0422) for NO ₂ at lag 03 days, and 1.0048 (1.0013–1.0083) for O₃ at lag 04 days, respectively. Stratified analyses showed that individuals aged 65 years and older were more susceptible only to O₃. The significant adverse effect of O₃ was significantly stronger in the warm season than in the cold season, while no significant difference was found between males and females. Overall, 4.23% (5,576 cases) of non-accidental deaths were attributable to excess exposure to air pollution exceeding the WHO air quality guidelines. Conclusion: Short-term exposure to PM _2.5 , PM ₁₀ , SO ₂ , NO ₂ and O ₃ was significantly associated with elevated non-accidental mortality in Shantou, a coastal subtropical city, imposing a considerable disease burden. Our findings highlight the urgent need for effective air pollution control strategies to reduce the related disease burden.