Effects of ambient air pollution on obesity and ectopic fat deposition: a protocol for a systematic review and meta-analysis

Mehnaz Munir, Sandi M Azab, Shrikant I Bangdiwala, Om Kurmi, Dany Doiron, Jeffrey Brook, Laura Banfield, Russell J de Souza

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Introduction - Globally, the prevalence of obesity tripled from 1975 to 2016. There is evidence that air pollution may contribute to the obesity epidemic through an increase in oxidative stress and inflammation of adipose tissue. However, the impact of air pollution on body weight at a population level remains inconclusive. This systematic review and meta-analysis will estimate the association of ambient air pollution with obesity, distribution of ectopic adipose tissue, and the incidence and prevalence of non-alcoholic fatty liver disease among adults. Methods and analysis.The study will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for conduct and reporting. The search will include the following databases: Ovid Medline, Embase, PubMed, Web of Science and Latin America and the Caribbean Literature on Health Sciences, and will be supplemented by a grey literature search. Each article will be independently screened by two reviewers, and relevant data will be extracted independently and in duplicate. Study-specific estimates of associations and their 95% Confidence Intervals will be pooled using a DerSimonian and Laird random-effects model, implemented using the RevMan software. The I2 statistic will be used to assess interstudy heterogeneity. The confidence in the body of evidence will be assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.Ethics and disseminationAs per institutional policy, ethical approval is not required for secondary data analysis. In addition to being published in a peer-reviewed journal and presented at conferences, the results of the meta-analysis will be shared with key stakeholders, health policymakers and healthcare professionals.Prospero registration numberCRD42023423955.
Original languageEnglish
Article numbere080026
Number of pages7
JournalBMJ Open
Issue number2
Early online date15 Feb 2024
Publication statusE-pub ahead of print - 15 Feb 2024

Bibliographical note

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.


  • Obesity
  • Systematic review
  • body mass index
  • Preventive Medicine
  • Humans
  • Body Weight
  • Air Pollution
  • Research Design
  • Adult
  • Meta-Analysis as Topic
  • Systematic Reviews as Topic


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