Ambient particulate air pollution and circulating C-reactive protein level: A systematic review and meta-analysis.
Int J Hyg Environ Health. 2019 06 ;222(5):756-764. Epub 2019 May 16. PMID: 31103472
BACKGROUND: Ambient particulate air pollution is a major threat to the cardiovascular health of people. Inflammation is an important component of the pathophysiological process that links air pollution and cardiovascular disease (CVD). A classical marker of inflammation-C-reactive protein (CRP), has been recognized as an independent predictor of CVD risk. Exposure to ambient particulate matter (PM) may cause systemic inflammatory response but its association with CRP has been inconsistently reported.
OBJECTIVES: To estimate the potential effects of short-term and long-term exposures to ambient particulate air pollution on circulating CRP level based on previous epidemiological studies.
METHODS: A systematic literature search of PubMed, Web of Science, Embase, and Scopus databases for publications up to January 2018 was conducted for studies reporting the association between ambient PM (PMor PM, or both) and circulating CRP level. We performed a meta-analysis for the associations reported in individual studies using a random-effect model and evaluated the effect modification by major potential modifiers.
RESULTS: This meta-analysis comprised data from 40 observational studies conducted on 244,681 participants. These included 32 (27 PMstudies and 13 PMstudies) and 11 (9 PMstudies and 5 PMstudies) studies that investigated the associations of CRP with short-term and long-term exposure to particulate air pollution, respectively. A 10μg/mincrease in short-term exposure to PMand PMwas associated with increases of 0.83 % (95% CI: 0.30%, 1.37%) and 0.39% (95% CI: -0.04%, 0.82%) in CRP level, respectively, and a 10μg/mincrease in long-term exposure to PMand PMwas associated with much higher increases of 18.01% (95% CI: 5.96%, 30.06%) and 5.61% (95% CI: 0.79%, 10.44%) in CRP level, respectively. The long-term exposure to particulate air pollution was more strongly associated with CRP level than short-term exposure and PMhad a greater effect on CRP level than PM.
CONCLUSION: Exposure to ambient particulate air pollution is associated with elevated circulating CRP level suggesting an activated systemic inflammatory state upon exposure, which may explain the association between particulate air pollution and CVD risk.