OBJECTIVES: To examine the association among acute bronchiolitis-related hospitalisation in children, meteorological variation and outdoor air pollution. METHODS: We obtained the daily counts of acute bronchiolitis-related admission of children≤2 years old from all public hospitals, meteorological data and outdoor air pollutants' concentrations between 1 January 2008 and 31 December 2017 in Hong Kong. We used quasi-Poisson generalised additive models together with distributed lag non-linear models to estimate the associations of interest adjusted for confounders. RESULTS: A total of 29 688 admissions were included in the analysis. Increased adjusted relative risk (ARR) of acute bronchiolitis-related hospitalisation was associated with high temperature (ambient temperature and apparent temperature) and was marginally associated with high vapour pressure, a proxy for absolute humidity. High concentration of NO(2) was associated with elevated risk of acute bronchiolitis admission; the risk of bronchiolitis hospitalisation increased statistically significantly with cumulative NO(2) exposure over the range 66.2-119.6 µg/m(3). For PM(10), the significant effect observed at high concentrations appears to be immediate but not long lasting. For SO(2), ARR increased as the concentration approached the 75th percentile and then decreased though the association was insignificant. CONCLUSIONS: Acute bronchiolitis-related hospitalisation among children was associated with temperature and exposure to NO(2) and PM(10) at different lag times, suggesting a need to adopt sustainable clean air policies, especially to target pollutants produced by motor vehicles, to protect young children's health.