Particulate Matter 2.5 and Respiratory Symptoms in Urban and Suburban Schoolchildren in Ho Chi Minh City, Vietnam

Abstract

Objective: To document the pattern of particulate matter 2.5 (PM2.5) concentration in urban and suburban schools in Ho Chi Minh City (HCMC) and to estimate the prevalence of wheezing and rhinitis among schoolchildren according to sociodemographic characteristics and school-related conditions.Material and Methods: A cross-sectional study was conducted in two suburban and two urban schools in HCMC. PM2.5 concentrations were monitored hourly from August to December in 2022. Children aged 9-13 years (N=1,033) provided data on wheezing and rhinitis symptoms in the previous year. The daily levels of PM2.5 were monitored in each school. Respiratory symptoms were compared between areas and across school-related conditions.Results: Geometric means of the daily PM2.5 concentration in the suburban and urban areas were 61.2 μg/m3 and 31.0 μg/m3, respectively (p-value<0.001). In both areas, PM2.5 levels increased in the evening to high levels at night and early morning. The prevalence of respiratory symptoms did not differ significantly between the suburban and urban areas: wheezing 20.6% and 16.9%, and rhinitis 55.7% and 61.5%, respectively. However, school-related conditions in which the prevalence was increased were travelling to school by bus, spending more than 15 minutes/day on the road and attending extra classes outside normal school hours.Conclusion: Despite the significantly higher PM2.5 levels in suburban schools, the prevalence of wheezing and rhinitis did not reveal significant differences between areas. However, respiratory symptoms were more common among those travelling by bus, having been infected with Coronavirus Disease-19 (COVID-19), spending longer time on the road and attending classes outside normal school hours.