Ambient air pollution is associated with cardiac repolarization abnormalities in healthy adults

Ambient air pollution has been associated with acute cardiovascular events; however, the underlying mechanisms remain incompletely understood. We aimed to examine the impacts of ambient air pollutants on cardiac ventricular repolarization in a highly polluted urban region.

Seventy-three healthy non-smoking young adults (66% female, mean age of 23.3 ± 5.4 years) were followed with four repeated 24-h electrocardiogram recordings in 2014-2016 in Beijing, China. Continuous concentrations of ambient particulates in size fractions of 5-560 nm diameter, black carbon (BC), nitrogen dioxide (NO₂), carbon monoxide (CO), sulfur dioxide (SO₂), and ozone (O₃) were measured at a fixed-location air pollution monitoring station. Generalized linear mixed models, with adjustment for individual risk factors, time-varying factors and meteorological parameters, were used to evaluate the effects of air pollution on 5-min segments of heart rate-corrected QT interval (QTc), an index of cardiac ventricular repolarization.

During the study period, the mean levels of number concentrations of particulates in size range of 5-560 nm (PNC_5-560) were 20,711 particles/cm³. Significant increases in QTc of 0.56% (95% CI: 0.27, 0.84) to 1.76% (95% CI: 0.73, 2.79) were associated with interquartile range increases in PNC_50-560 at prior 1-5 moving average days. Significant increases in QTc were also associated with increases in exposures to traffic-related air pollutants (BC, NO₂ and CO), a combustion pollutant SO₂, and the secondary pollutant O₃. The associations were stronger in participants who were male, overweight, with abdominal obesity, and with higher levels of high-sensitivity C-reactive protein.

Our findings suggest that exposures to higher levels of ambient particulates in small size fractions and traffic pollutants were associated with cardiac repolarization abnormalities in healthy adults, and the cardio-metabolic risks may modify the adverse cardiac effects attributable to air pollution.