Associations between exposure to air pollution and obesity and related anthropometric measurements in adults: a systematic review and meta-analysis

OBJECTIVE: The present study sought to synthesize available evidence for the association of ambient air pollutants on overweight and obesity and other commonly used anthropometric measurements. METHODS: We searched five databases (OVID Medline, Embase, PubMed, Web of Science, and LILAC) and grey literature till December 2024. We included studies that met all of the following criteria in the review: participants ≥18 years and reported an association between PM_2.5, NO₂, O₃ or SO₂ and at least one of the outcomes of interest and an observational study design. Two independent reviewers assessed the eligibility of articles and extracted the data. Meta-analyses were conducted using the random-effects model for outcomes with ≥2 studies. Risk of bias and evidence certainty were assessed using the JBI tools and OHAT, and GRADE frameworks. FINDINGS: Based on meta-analysis of 41 included studies (n ≈ 150 to 3,900,000), PM_2.5 was associated with 0.93 kg/m² (95 % CI [0.69, 1.16]), 1.17 cm (95 % CI [0.58, 1.75]) and 1.60 % (95 % CI [0.75 to 2.45]) higher body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) respectively. Similarly, increment of PM_2.5 and NO₂ was associated with change in BMI and WC and increased risk of general and abdominal obesity. The results regarding O₃ and SO₂ were inconsistent. The certainty of the evidence ranged from very low to high. CONCLUSIONS: PM_2.5 and NO₂ levels were positively correlated with most of the obesity-related outcomes emphasizing the importance of considering environmental factors in public health strategies to manage obesity. However, more longitudinal studies are needed to establish causality and inform public health.