Table 1

Selected characteristics of BetaGene study participants with complete FSIGT, oGTT, and air pollution measurements

NMeanSDMedian25th, 75th quantiles
Age (years)1,02334.58.134.328.8, 39.5
BMI (kg/m2)1,02329.76.228.725.5, 32.7
Percent body fat1,01333.98.635.327.5, 40.4
Measurements obtained from FSIGT
  SI (×10−5 min−1 per pmol/L)1,0234.272.334.423.07, 6.21
  AIRg (pmol/L × 10 min)1,0232,8402,1712,4901,436, 4,258
  DI (SI × AIRg)1,02311,5658,02111,2326,647, 17,782
 Insulin MCR (mL/min/m2)1,0228.25.59.15.8, 12.9
 Insulin FDR (min−1 × 100)1,02218.311.820.013.2, 27.6
Measurements obtained from oGTT
 Fasting glucose (mmol/L)1,0235.10.75.14.8, 5.4
 2-h glucose (mmol/L)1,0237.62.27.46.1, 8.8
 Fasting insulin (pmol/L)1,02243.129.742.024.0, 72.0
 2-h insulin (pmol/L)1,022347.1274.5360.0222.0, 606.0
 HOMA-IR (mmol/L × mU/L)1,0221.611.21.610.95, 2.70
Lipids§
 Cholesterol (mg/dL)1,008174.634.0171.0152.0, 196.0
  HDL-C (mg/dL)1,00846.411.145.039.0, 52.5
  LDL-C (mg/dL)989105.328.6103.085.6, 123.2
 HDL-C–to–LDL-C ratio × 10098944.816.643.934.2, 56.2
 Triglycerides (mg/dL)1,00896.759.198.064.0, 141.0
Physical activity and dietary intakes
 Total weekly physical activity (min/week)98450169021745, 600
 Total daily caloric intake (kcal/day)9872,3231,0242,2911,749, 2,922
 Daily vitamin C intake (mg/day)987153.9102.9157.1102.5, 232.0
 Daily β-carotene intake (μg/day)9875,1673,9405,7193,219, 8,529
Contextual variables
 Proportions of households below federally designated poverty rate#1,0230.220.120.210.12, 0.29
 Proportion of respondents aged >25 years with highest attained education#
   No education1,0230.070.050.070.03, 0.10
   ≤High school1,01719.8892.075.792.34, 12.65
   Some college or technical school1,0230.230.100.220.14, 0.31
   >4 years of college1,0230.110.100.080.04, 0.15
  • ‡Log transformation was applied and geometric means (SDs) are presented.

  • §Lipid concentrations were measured using fasting blood.

  • ‖For conversion of measurements from conventional units to Système International (SI) units, multiply by a conversion factor of 0.02586.

  • ¶For conversion of measurements from conventional units to Système International units, multiply by a conversion factor of 0.01129.

  • #Different geographic information system tools (intersect, dissolve and calculate field) were applied to calculate the proportion of the census block groups that fell within each of the 300 m buffers for each of the geocoded addresses.