Source specific PM_2.5 associated with heart rate variability in the elderly with coronary heart disease: A...

There is increasingly concern that PM_2.5 constituents play a significant role in PM_2.5-related cardiovascular outcomes. However, little is known about the associations between specific constituents of PM_2.5 and risk for cardiovascular health. To evaluate the exposure to specific chemicals of PM_2.5 from various sources and their cardiac effects, a longitudinal investigation was conducted with four repeated measurements of elderly participants' HRV and PM_2.5 species in urban Beijing. Multiple chemicals in PM_2.5 (metals, ions and PAHs) were characterized for PM_2.5 source apportionment and personalized exposure assessment. Five sources were finally identified with specific chemicals as the indicators: oil combustion (1.1%, V & PAHs), secondary particle (11.3%, SO₄^2- & NO₃^-), vehicle emission (1.2%, Pd), construction dust (28.7%, Mg & Ca), and coal combustion (57.7%, Se & As). As observed, each IQR increase in exposure to oil combustion (V), vehicle emission (Pd), and coal combustion (Se) significantly decreased rMSSD by 13.1% (95% CI: -25.3%, -1.0%), 27.4% (95% CI: -42.9%, -7.6%) and 24.7% (95% CI: -39.2%, -6.9%), respectively, while those of PM_2.5 mass with decreases of rMSSD by 11.1% (95% CI: -19.6%, -1.9%) at lag 0. Elevated exposures to specific sources/constituents of PM_2.5 disrupt cardiac autonomic function in elderly and have more adverse effects than PM_2.5 mass. In the stratified analysis, medication and gender modify the associations of specific chemicals from variable sources with HRV. The findings of this study provide evidence on the roles of influential constituents of ambient air PM_2.5 and their sources in terms of their adverse cardiovascular health effects.