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. 2014 May 16;122(9):896–905. doi: 10.1289/ehp.1307725

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Cohort-specific and meta-analysis estimates of association of NO₂ (A), NO_x (B), traffic load at major road fragments (C), and traffic intensity at the nearest road (D) with systolic BP and hypertension. Results are presented per given increments. I² is a measure of heterogeneity between cohorts, and p_het is a p-value for the Q-test of heterogeneity.