Long-term Exposure to Air Pollution and Lipometabolic Disturbance: A Systematic Review and Meta-Analysis

Objectives To reveal the chronic effects of air pollutants on lipometabolic disturbance via detectable lipoprotein parameters. Study Design This is a systematic review and meta-analysis. Methods Seven online databases were searched to conduct a meta-analysis of epidemiological studies examining the relationship between air pollution and lipid parameter levels. Subgroup analysis was additionally carried out for each air pollutant studied. Results A total of 2,274 records were retrieved, resulting in 10 studies included in the final quantitative meta-analysis, comprising seven studies in Europe and the United States and three studies in mainland China. Using a random-effect model, the results showed that for each 10 μg/m3 increment in PM2.5, TC, LDL-C, and HDL-C levels and metabolic syndrome (MetS) incidence increased by 3.31% (95% CI: 2.29%, 8.91%), 2.34% (95% CI: 1.30%, 3.39%),-1.57% (95% CI: −1.85%, −1.28%), and 4.33% (95% CI: 2.69%, 5.98%), respectively; for each 10 μg/m3 increment in PM10, LDL-C, TG, HDL-C levels increased by 5.27% (95% CI: 2.03%, 8.50%), −0.24% (95% CI: −0.95%, −0.47%), and 0.45% (95% CI: −0.57%, 1.47%), respectively; for each 10 μg/m3 increment in NO2, TG and HDL-C levels increased by 4.18% (95% CI: 1.12%, 7.23%) and −0.51% (95% CI: −2.61%, 1.58%), respectively. No significant associations were detected for combinations of air pollutants on lipometabolic disturbance. Conclusion Increased air pollutant exposure is significantly associated with fluctuation in blood lipid parameter levels, which can be an indicator of the body’s lipometabolic disturbance. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by the National Natural Science Foundation of China (81872649), National Key R&D Program of China (2017YFC0211600), Scientific Research Project of Beijing Educational Committee (KM201910025023), and HERCULES Exposome Research Centre (P30ES019776). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes This study was conducted using standard methods which follow the Preferred Reporting Items for Systematic Review and Meta-Analysis (PISMA)(J et al., 2020; "Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation," 2016). Seven electronic databases, including China National Knowledge Infrastructure (CNKI), Wanfang, Vip, SinoMed, Pubmed, EMBASE, and the Cochrane Library, were searched for peer-reviewed articles published from 2000 to January 28, 2020. Keywords searched included: ("Air Pollution" OR "Pollution, Air" OR "Air Quality" OR "Ultrafine Fibers" OR "Airborne Particulate Matter" OR "Particulate Matter, Airborne" OR "Air Pollutants, Particulate" OR "Particulate Air Pollutants" OR "Ambient Particulate Matter" OR "Particulate Matter, Ambient" OR "Ultrafine Particulate Matter" OR “Particulate Matter, Ultrafine” OR "Ultrafine Particles" OR "Particles, Ultrafine") AND ("Cardiovascular Disease" OR "Disease, Cardiovascular" OR "Diseases, Cardiovascular" OR "HDL" OR "LDL" OR "cholesterol" OR " cholesterin" OR "cholesteric" OR "TC" OR "TG" OR "dyslipidaemia" OR "HDL-C" OR "LDL-C") AND ("Cohort" OR "Cross-sectional" OR "Case control" OR "Case-control" OR "Epidemiology OR "Epidemiological"). Additionally, references of included literature and one previously published systematic review were manually retrieved.