Table 3.

Categorical comparison of GIS-based exposure estimates and biological monitoring results using Kruskal-Wallis one-way ANOVA by ranks

Exposure categorySubjects (n)Median 1-OHPG (pmol/mL)P
Among nonsmokers only (n = 299 for residential and 217 for workplace)
Urban residence1220.160.84
Rural residence1770.17
Residential traffic density* ≥100,000360.050.12
Residential traffic density* 1-99,9991600.21
Residential traffic density 01030.11
Workplace traffic density* ≥100,000560.050.38
Workplace traffic density* 1-99,999980.21
Workplace traffic density 0630.28
  • * Traffic density (VMT/d/mi2) within 500 feet of location.

  • No measured roads within 500 feet.