Exposure Error Masks the Relationship Between Traffic-Related Air Pollution and Heart Rate Variability

Abstract

Objective: 

We examined whether more precise exposure measures would better detect associations between traffic-related pollution, elemental carbon (EC), nitrogen dioxide (NO₂), and heart rate variability (HRV).

Methods: 

Repeated 24-hour personal and ambient pm_2.5, EC, and NO₂ were measured for 30 people living in Atlanta, GA. The association between HRV and either ambient concentrations or personal exposures was examined using linear mixed effects models.

Results: 

Ambient pm_2.5, EC, NO₂, and personal pm_2.5 were not associated with HRV. Personal EC and NO₂ measured 24 hours before HRV were associated with decreased RMSSD, PNN50, and HF and with increased LF/HF. RMSSD decreased by 10.97% (95% confidence interval: −18.00 to −3.34) for an inter-quartile range change in personal EC (0.81 μg/m³).

Conclusions: 

Results indicate decreased vagal tone in response to traffic pollutants, which can best be detected with precise personal exposure measures.