Table 1.

Baseline characteristics of the Atherosclerosis Risk in Communities study population, stratified above and below site-specific median annual average PM2.5 concentration

CharacteristicAnnual Average PM2.5 (μg/m3)
≤Site-Specific Median>Site-Specific Median
Number of participants54995498
Age, mean (SD), yr63 (6)63 (6)
Female, n3033 (55%)3128 (57%)
Black, n1177 (21%)1231 (22%)
Smoker, n
 Never2332 (43%)2211 (41%)
 Former2362 (43%)2420 (44%)
 Current790 (14%)822 (15%)
eGFR, mean (SD), ml/min per 1.73 m286 (16)86 (16)
eGFR<60 ml/min per 1.73 m2, n346 (6%)349 (6%)
UACR, median (IQR), mg/g3.4 (5.8)4.0 (6.4)
C-reactive protein, median (IQR), mg/L2.5 (4.4)2.5 (4.4)
Body mass index, mean (SD), kg/m228.8 (5.5)28.8 (5.7)
Systolic BP, mean (SD), mm Hg127 (19)128 (19)
Hypertension, n2546 (46%)2678 (49%)
Diabetes mellitus, n872 (16%)943 (17%)
Composite cardiovascular disease, n1026 (19%)1090 (20%)
Neighborhood socioeconomic score (SD)0.4 (5.4)−0.3 (5.5)
Annual household income, n
 <$25,0001591 (30%)1699 (32%)
 ≥$25,0003676 (68%)3536 (66%)
 Refused124 (2%)126 (2%)
Education, n
 ≤11 yr1045 (19%)1042 (19%)
 12–16 yr2273 (41%)2358 (43%)
 17–21 yr2171 (40%)2091 (38%)
Temperature, mean (SD), °C12.4 (4.3)13.0 (4.0)
  • Median annual average PM2.5 concentration for each site: Forsyth County, 15.3 μg/m3; Jackson, 12.2 μg/m3; Minneapolis, 9.4 μg/m3; and Washington County, 14.6 μg/m3. PM2.5, particulate matter <2.5 μm in aerodynamic diameter; UACR, urinary albumin-creatinine ratio; IQR, interquartile range.