Table 2. Association Between Annual Ambient Particulate Matter Air Pollution and Bone Mineral Content Corrected by Bone Area at the Hip and Lumbar Spine Sitesa.
| Site, Model | Bone Mineral Content, Mean Difference (95% CI), g | |
|---|---|---|
| Per 3 μg/m3 Increase in PM2.5 | Per 1 μg/m3 Increase in BC | |
| Hip | ||
| Model 1b | −0.14 (−0.39 to 0.10) | −0.80 (−1.59 to −0.02) |
| Model 2c | −0.15 (−0.32 to 0.02) | −0.39 (−1.01 to 0.23) |
| Model 3d | −0.13 (−0.29 to 0.03) | −0.36 (−0.96 to 0.25) |
| Model 4e | −0.13 (−0.30 to 0.03) | −0.35 (−0.96 to 0.25) |
| Lumbar spine | ||
| Model 1b | −0.62 (−1.13 to −0.10) | −1.22 (−2.95 to 0.51) |
| Model 2c | −0.62 (−1.12 to −0.11) | −1.18 (−2.89 to 0.53) |
| Model 3d | −0.59 (−1.09 to −0.09) | −1.17 (−2.86 to 0.53) |
| Model 4e | −0.57 (−1.06 to −0.07) | −1.13 (−2.81 to 0.54) |
Abbreviations: BC, black carbon; PM2.5, ambient particulate matter air pollution less than 2.5 µm in aerodynamic diameter.
Associations were estimated using mixed effects linear models with nested random intercepts (household within village) using inverse-probability weighting.
Model 1 was adjusted for bone area (natural cubic spline with 3 df), a dual-energy x-ray absorptiometry machine indicator, sex, age (second-degree polynomial), and a sex-by-age interaction.
Model 2 included model 1 and was further adjusted for percentage lean and percentage fat body mass.
Model 3 added to model 2 log-transformed intake of fruit, vegetables, and calcium; weight-bearing physical activity; smoking status; and household cooking fuel.
Model 4 (main model) was also adjusted for socioeconomic confounders, including occupation, education, and standard of living index.