Figure 2

Associations between daily and 30-min average pollutant measurements and changes in heart rate and HRV parameters, in single pollutant (circle) and two-pollutant (triangle) models. SDNN standard deviation of normal-to-normal (NN) intervals, RMSSD root mean square of successive NN interval differences, HF high-frequency power, LF low-frequency power, LF:HF the LF to HF ratio, bpm beats per minute, ms milliseconds. Multivariate models with random subject intercepts in daily average models, and additional random slopes in 30-min average models, adjusted for continuous temperature (degrees Celsius), alcohol intake (yes/no) and caffeine intake (yes/no) in the last 24 h. In daily average models, β-coefficients represent the change per IQR increase in pollutant exposure in a single-pollutant model (circle) or a two-pollutant (triangle) model (i.e. air pollutant + noise). In 30-min average models. β-coefficients represent the change per IQR increase in pollutant exposure for heart rate, SDNN and RMSSD and the % change per IQR increase in exposure for LF, HF and LF:HF ratio, in a single-pollutant model (filed circle) or a two-pollutant (filed triangle) model (i.e. LF, HF and LF:HF outcomes were natural log transformed. UFPs were log transformed to base 5 and BC exposures were natural log transformed corresponding approximately to the IQRs for the untransformed exposure), β-coefficients for noise are shown in the following order: noise estimate in a single-pollutant model, followed by noise estimate in two-pollutant models with UFPs and BC, respectively. For daily average results, refer to Supplementary Tables S3, S4 (single-pollutant model) and S5, S6 (two-pollutant models). For 30-min average results, refer to Supplementary Table S7 (single-pollutant models) and S8 (two-pollutant models). Figures and tabulated results for fixed-site regional pollutants appear in the supplementary material.