Validity of using ambient concentrations as surrogate exposures at the individual level for fine particle and black carbon: A systematic review and meta-analysis

• Published in: Environmental pollution (1987) Vol. 312; p. 120030
• Main Authors: Chen, Jiayao, Jahn, Heiko J., Sun, Haitong Zhe, Ning, Zhi, Lu, Weisheng, Ho, Kin Fai, Ward, Tony J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2022
• Subjects: Air Pollutants - analysis; Black carbon; Carbon - analysis; Correlation coefficient; Databases, Factual; Environmental Exposure - analysis; Fine particles; Fixed-site monitoring; Humans; Meta-analysis; Particulate Matter - analysis; Personal exposure; Regression Analysis; Soot - analysis; Correlation coefficient; Personal exposure; Black carbon; Fine particles; Fixed-site monitoring; Meta-analysis
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2022.120030

Exposure measurement error is an important source of bias in epidemiological studies. We assessed the validity of employing ambient (outdoor) measurements as proxies of personal exposures at individual levels focusing on fine particles (PM2.5) and black carbon (BC)/elemental carbon (EC) on a global scale. We conducted a systematic review and meta-analysis and searched databases (ISI Web of Science, Scopus, PubMed, Ovid MEDLINE®, Ovid Embase, and Ovid BIOSIS) to retrieve observational studies in English language published from 1 January 2006 until 5 May 2021. Correlation coefficients (r) between paired ambient (outdoor) concentration and personal exposure for PM2.5 or BC/EC were standardized as effect size. We used random-effects meta-analyses to pool the correlation coefficients and investigated the causes of heterogeneity and publication bias. Furthermore, we employed subgroup and meta-regression analyses to evaluate the modification of pooled estimates by potential mediators. This systematic review identified thirty-two observational studies involving 1744 subjects from ten countries, with 28 studies for PM2.5 and 11 studies for BC/EC. Personal PM2.5 exposure is more strongly correlated with ambient (outdoor) concentrations (0.63, 95% confidence interval [CI]: 0.57–0.68) than personal BC/EC exposure (0.49, 95% CI: 0.38–0.59), with significant differences in ṝ (0.14, 95% CI: 0.03–0.25; p < 0.05). The results demonstrated that the health status of participants was a significant modifier of pooled correlations. In addition, the personal to ambient (P/A) ratio for PM2.5 and average ambient BC/EC levels were potential effect moderators of the pooled ṝ. The funnel plots and Egger's regression test indicated inevident publication bias. The pooled estimates were robust through sensitivity analyses. The results support the growing consensus that the validity coefficient of proxy measures should be addressed when interpreting results from epidemiological studies to better understand how strong health outcomes are affected by different levels of PM2.5 and their components. [Display omitted] •Studies that investigated ambient/outdoor-personal exposure correlations were reviewed.•This review provides separate pooled estimates for PM2.5 and BC/EC.•Significant differences in pooled correlations between PM2.5 and BC/EC were shown.•Participants' health status and P/A ratios are modifiers of pooled correlations for PM2.5.•Health status and ambient (outdoor) concentrations are modifiers of BC/EC correlations.