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Table 3 Spearman’s rank correlation coefficients for exposure variables from the 5-minute time period

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

  PM2.5 Ozone CO CO2 Formaldehyde NO2 NOx
PM2.5 (n = 3314) 1.0       
Ozone (n = 4406) 0.33 1.0      
CO (n = 4353) 0.24 −0.07 1.0     
CO2 (n = 4371) 0.27 −0.06 0.78 1.0    
Formaldehyde (n = 1784) 0.56 0.36 0.79 0.77 1.0   
NO2 (n = 4406) 0.21 −0.007 0.84 0.72 0.60 1.0  
NOx (n = 4406) −0.13 −0.34 0.79 0.70 0.52 0.81 1.0
  1. Sample sizes are the total number of repeated observations across all 16 subjects.