Table 1.

Demographic characteristics of women in the Women's Health Initiative at enrollment (N = 9041) with available bone mineral density and long-term air pollution data.

Variable	<60 years old		60–69 years old		≥70 years old
	N = 3132		N = 3992		N = 1917
	Mean/n	SD/%	Mean/n	SD/%	Mean/n	SD/%
Bone mineral density (corrected), g/cm2
Total hip	0.90	0.13	0.84	0.13	0.79	0.13
Femoral neck	0.77	0.12	0.71	0.12	0.67	0.11
Lumbar spine	1.01	0.15	0.97	0.17	0.97	0.18
Whole body	1.05	0.10	1.00	0.10	0.97	0.11
Ethnicity
White (non-Hispanic)	2265	25.05%	3187	35.25%	1616	17.87%
Black	517	5.72%	520	5.75%	192	2.12%
Hispanic	266	2.94%	206	2.28%	80	0.88%
Other race	81	0.90%	71	0.79%	23	0.25%
Not available	3	0.03%	8	0.09%	6	0.07%
Education level
High school or less	815	9.01%	1342	14.84%	644	7.12%
College or vocational school	1498	16.57%	1763	19.50%	886	9.80%
Grad school or higher	769	8.51%	862	9.53%	375	4.15%
Not available	23	0.25%	25	0.28%	12	0.13%
Household income
<$49,999	1752	19.38%	2875	31.80%	1500	16.59%
$50,000–$99,999	933	10.32%	703	7.78%	218	2.41%
>$100,000	253	2.80%	141	1.56%	39	0.43%
Not available	194	2.15%	273	3.02%	160	1.77%
Alcohol consumption
Never	445	4.92%	716	7.92%	346	3.83%
Former	647	7.16%	834	9.22%	446	4.93%
<7 drinks per week	1788	19.78%	2101	23.24%	937	10.36%
≥7 drinks per week	231	2.56%	315	3.48%	167	1.85%
Not available	21	0.23%	26	0.29%	21	0.23%
Smoking
Never	1669	18.46%	2205	24.39%	1114	12.32%
Former	1112	12.30%	1467	16.23%	676	7.48%
Current	323	3.57%	285	3.15%	80	0.88%
Not available	28	0.31%	35	0.39%	47	0.52%
Physical activity, MET-hours/week	0.32	0.18	0.04	0.20	0.05	0.23
Body mass index, kg/m2
≤18.5	17	0.19%	37	0.41%	25	0.28%
18.6–24.9	862	9.53%	1189	13.15%	694	7.68%
≥25 kg/m2	2243	24.81%	2751	30.43%	1193	13.20%
Not available	10	0.11%	15	0.17%	5	0.06%

SD: standard deviation; CT: clinical trial; MET: metabolic equivalent.