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Original research
Short-term association among meteorological variation, outdoor air pollution and acute bronchiolitis in children in a subtropical setting
  1. Shuk Yu Leung1,
  2. Steven Yuk Fai Lau2,
  3. Ka Li Kwok1,
  4. Kirran N. Mohammad2,
  5. Paul Kay Sheung Chan3,
  6. Ka Chun Chong2,4,5
  1. 1 Department of Paediatrics, Kwong Wah Hospital, Hong Kong, China
  2. 2 School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China
  3. 3 Department of Microbiology, The Chinese University of Hong Kong, Hong Kong, China
  4. 4 Clinical Trials and Biostatistics Laboratory, Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
  5. 5 Centre for Health Systems and Policy Research, The Chinese University of Hong Kong, Hong Kong, China
  1. Correspondence to Dr Ka Chun Chong, School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China; marc{at}


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 NO2 was associated with elevated risk of acute bronchiolitis admission; the risk of bronchiolitis hospitalisation increased statistically significantly with cumulative NO2 exposure over the range 66.2–119.6 µg/m3. For PM10, the significant effect observed at high concentrations appears to be immediate but not long lasting. For SO2, 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 NO2 and PM10 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.

  • asthma epidemiology
  • infection control
  • respiratory infection
  • viral infection

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  • Contributors SYL and KCC conceived the study. SYL, KCC and SYFL performed the analysis. KLK and SYL contributed to the acquired data of the study. SYL, PKSC, KCC and KM contributed to the results interpretation. SYL, KCC, SYFL, PKSC and KM drafted the paper. All authors have read and approved the final paper.

  • Funding This work was supported by the National Natural Science Foundation of China (71974165, 81473035) and partially supported by Health and Medical Research Fund (INF-CUHK-1, 19181132).

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data may be obtained from a third party and are not publicly available. The sharing of data is restricted by the Hong Kong Hospital Authority.

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