PM2.5 and Respiratory Symptoms among Primary Schoolchildren in Bangkok, Thailand: A School-Based Cross-Sectional Study

Background: Exposure to fine particulate matter (PM2.5) has been linked to adverse respiratory health in children. However, limited studies in Bangkok have examined the combined influence of environmental exposure and health perceptions. The objective of this study is to investigate the association between PM2.5 concentrations and respiratory symptoms among primary schoolchildren aged 7—12 years in Bangkok, across districts categorized by differing levels of air pollution. Methods: A cross-sectional study was conducted among 388 primary schoolchildren in Bangkok, recruited through cluster sampling from districts classified into three PM2.5 pollution zones based on data from the Pollution Control Department. Respiratory symptoms were assessed using the Thai standard ATS-DLD-78C questionnaire, and multivariate logistic regression was applied to estimate adjusted odds ratios (aORs). Results: Multivariate logistic regression analysis identified a significant association between environmental exposure and respiratory symptoms among children. After adjusting for potential confounders, children residing in high air pollution zones (red areas) exhibited significantly increased odds of developing bronchial asthma compared with those living in low-pollution zones (yellow areas) (aOR ¼1.28, 95% CI: 1.03—4.09, p < 0.001). Persistent cough, persistent phlegm, and chronic bronchitis exhibited no statistically significant associations with PM2.5 exposure levels after adjustment. Conclusion: Elevated PM2.5 exposure remains a significant risk factor for respiratory morbidity among Bangkok schoolchildren. Health perception factors strongly influence preventive behaviors, underscoring the value of theory-guided health promotion. Interventions integrating environmental monitoring and behavioral support are urgently needed to mitigate the health impacts of air pollution on urban schoolchildren. Keywords: Air pollution, Schoolchildren, PM2.5, Respiratory symptoms, Urban settings, Thailand