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Table 6 Results from single-pollutant linear mixed-model sensitivity analysis: Observations with the smallest and largest 5% of pollutant values (10% total) were removed to evaluate the influence of outlying exposure values on the observed associations

From: Traffic-related air pollution exposures and changes in heart rate variability in Mexico City: A panel study

    SDNN HF LF LF/HF
  n IQR β p-value β p-value β p-value β p-value
PM2.5 (μ g/m3)           
 5-min 2982 8.43 2.30 0.01 0.81 0.73 1.99 0.33 1.22 0.50
 30-min 2826 8.62 0.09 0.92 1.71 0.48 0.46 0.82 −1.32 0.45
 60-min 2645 7.28 0.43 0.61 2.12 0.34 1.76 0.36 −0.48 0.77
 90-min 2459 6.56 0.33 0.70 3.58 0.12 2.14 0.26 −1.44 0.38
Ozone (ppm)           
 5-min 3964 58.5 −0.40 0.72 −13.17 < 0.0001 −9.67 0.0001 4.18 0.08
 30-min 3706 60.2 −2.07 0.06 −10.72 0.0001 −7.82 0.001 3.28 0.15
 60-min 3448 62.8 −3.75 0.002 −13.78 < 0.0001 −11.06 < 0.0001 3.16 0.23
 90-min 3194 60.0 −6.23 < 0.0001 −19.14 < 0.0001 −16.86 < 0.0001 2.96 0.31
CO (ppm)           
 5-min 3917 5.60 −2.15 0.0001 1.56 0.31 −0.82 0.52 −2.37 0.04
 30-min 3676 8.57 −3.18 0.0006 3.03 0.22 −1.44 0.49 −4.36 0.02
 60-min 3424 8.88 −3.53 0.0007 0.23 0.93 −2.52 0.28 −2.78 0.21
 90-min 3170 7.98 −3.52 0.0003 −2.39 0.37 −2.35 0.31 0.07 0.98
CO2 (ppm)           
 5-min 3933 77.8 −1.81 0.007 1.11 0.54 −2.35 0.13 −3.43 0.01
 30-min 3678 90.2 −2.06 0.02 0.34 0.89 −2.55 0.20 −2.89 0.11
 60-min 3420 90.9 −3.75 0.0001 −2.27 0.38 −4.72 0.03 −2.29 0.24
 90-min 3168 92.3 −4.86 < 0.0001 −4.74 0.11 −7.26 0.004 −2.47 0.27
Formaldehyde (ppb)           
 5-min 1604 20.9 −0.81 0.31 1.93 0.39 −1.74 0.38 −1.74 0.03
 30-min 1495 26.3 −1.18 0.31 −1.52 0.63 −2.01 0.47 −0.52 0.83
 60-min 1367 24.6 −2.12 0.08 −6.29 0.04 −5.22 0.05 1.00 0.69
 90-min 1241 28.8 −4.22 0.006 −10.22 0.007 −8.24 0.02 2.34 0.47
NO2 (ppb)           
 5-min 3964 95.3 −2.85 < 0.0001 1.13 0.41 −2.46 0.03 −3.49 0.0006
 30-min 3706 111 −2.49 0.0001 1.17 0.52 −1.95 0.20 −3.05 0.03
 60-min 3448 136 −2.40 0.008 0.77 0.75 −1.96 0.34 −2.58 0.15
 90-min 3194 136 −2.69 0.006 −0.91 0.73 −1.36 0.56 −0.24 0.90
NOx (ppm)           
 5-min 3964 121 −3.07 < 0.0001 −0.83 0.46 −2.29 0.02 −1.48 0.09
 30-min 3706 172 −3.37 < 0.0001 −1.44 0.43 −3.03 0.06 −1.61 0.26
 60-min 3448 197 −4.02 < 0.0001 −2.10 0.34 −4.03 0.04 −1.85 0.28
 90-min 3194 200 −3.61 < 0.0001 −3.83 0.13 −3.34 0.14 0.58 0.78
  1. β-values are percent change in the outcome per IQR increase in exposure, controlling for sex, age, smoking status, ethnic origin, time of day, and study day. Sample sizes are the total number of repeated observations across all 16 subjects.
  2. Significant with α = 0.05.