Abstract
BackgroundExposure to ambient particulate matter (PM) has been associated with adverse cardiovascular effects in epidemiological studies. Current knowledge of independent effects of individual PM characteristics remains limited.MethodsUsing a semi-experimental design we investigated which PM characteristics were consistently associated with blood biomarkers believed to be predictive of the risk of cardiovascular events. We exposed healthy adult volunteers at 5 different locations chosen to provide PM exposure contrasts with reduced correlations among PM characteristics. Each of the 31 volunteers was exposed for 5 h, exercising intermittently, 3–7 times at different sites from March to October 2009. Extensive on-site exposure characterization included measurements of PM mass and number concentration, elemental- (EC) and organic carbon (OC), trace metals, sulfate, nitrate, and PM oxidative potential (OP). Before and 2 h and 18 h after exposure we measured acute vascular blood biomarkers - C-reactive protein, fibrinogen, platelet counts, von Willebrand Factor, and tissue plasminogen activator/plasminogen activator inhibitor-1 complex. We used two-pollutant models to assess which PM characteristics were most consistently associated with the measured biomarkers.Results and ConclusionWe found OC, nitrate and sulfate to be most consistently associated with different biomarkers of acute cardiovascular risk. Associations with PM mass concentrations and OP were less consistent, whereas other measured components of the air pollution mixture, including PNC, EC, trace metals and NO2, were not associated with the biomarkers after adjusting for other pollutants.
Highlights
Exposure to ambient particulate matter (PM) has been associated with cardiovascular health effects in epidemiological studies [1,2]
The current paper focuses on the associations of specific PM characteristics, including oxidative potential (OP), with acute vascular changes in healthy human volunteers
If we only showed two-pollutant model results with e.g. no significant associations with PM2.5 we would not be able to distinguish between the scenario of no associations with PM2.5 at all and the scenario of significant association with PM2.5 that was explained by a specific component when included in two-pollutant model
Summary
Exposure to ambient particulate matter (PM) has been associated with cardiovascular health effects in epidemiological studies [1,2]. PM composition is variable in time and space and is strongly dependent on (local) sources of emission [3]. This heterogeneity in physiochemical composition has been shown to affect PM toxicity [4]. Current knowledge of health effects of individual PM characteristics remains limited [2,6,7]. Exposure to ambient particulate matter (PM) has been associated with adverse cardiovascular effects in epidemiological studies. Current knowledge of independent effects of individual PM characteristics remains limited
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