Table 3.
Adjusteda odds ratios (aOR) and 95% confidence intervals (CI) of congenital heart defects and exposure to pollutantsb and traffic densityc for N cases (N=1641).
| Exposure levelsb | Heterotaxia | d-Transposition of the great arteries | Tetralogy of Fallot | Double outlet right ventricle - other | Double outlet right ventricle - TGA | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | ||
| CO (ppm) | 0.13–0.39 | 16 | Reference | 12 | Reference | 22 | Reference | 6 | Reference | 5 | Reference |
| 0.40–0.52 | 4 | 0.2 (0.1,0.7) | 9 | 0.8 (0.3,1.9) | 17 | 0.8 (0.4,1.6) | 3 | 0.5 (0.1,1.9) | 2 | NC | |
| 0.53–0.71 | 14 | 0.8 (0.4,1.7) | 16 | 1.4 (0.6,3.0) | 21 | 1.0 (0.5,1.9) | 2 | NC | 3 | 0.6 (0.1,2.5) | |
| 0.72–1.37 | 14 | 0.8 (0.4,1.8) | 12 | 0.9 (0.4,2.2) | 19 | 0.9 (0.5,1.8) | 2 | NC | 4 | 0.8 (0.2,3.2) | |
| NO (ppb) | 0.69–4.14 | 15 | Reference | 12 | Reference | 23 | Reference | 4 | Reference | 2 | -- |
| 4.15–8.15 | 12 | 0.7 (0.3,1.6) | 12 | 1.0 (0.5,2.4) | 20 | 0.8 (0.4,1.6) | 4 | 1.0 (0.2,4.0) | 2 | NC | |
| 8.16–20.19 | 14 | 0.8 (0.4,1.8) | 20 | 1.6 (0.7,3.4) | 27 | 1.1 (0.6,2.1) | 3 | 0.6 (0.1,2.9) | 6 | NC | |
| 20.20–67.34 | 13 | 0.8 (0.4,1.7) | 10 | 0.8 (0.4,2.0) | 18 | 0.8 (0.4,1.5) | 3 | 0.7 (0.1,3.2) | 4 | NC | |
| NO2 (ppb) | 2.40–13.36 | 13 | Reference | 10 | Reference | 18 | Reference | 3 | Reference | 4 | Reference |
| 13.37–16.81 | 20 | 1.4 (0.7,3.0) | 16 | 1.6 (0.7,3.6) | 34 | 1.8 (1.0,3.4) | 1 | NC | 3 | 0.7 (0.2,3.3) | |
| 16.82–20.53 | 14 | 1.0 (0.5,2.3) | 16 | 1.6 (0.7,3.6) | 26 | 1.4 (0.7,2.7) | 7 | 2.2 (0.6,8.9) | 3 | 0.7 (0.2,3.2) | |
| 20.54–38.94 | 14 | 1.0 (0.5,2.2) | 21 | 2.0 (0.9,4.4) | 22 | 1.2 (0.6,2.4) | 4 | 1.3 (0.3,5.8) | 7 | 1.7 (0.5,6.1) | |
| PM10 (μg/m3) | 7.90–25.24 | 17 | Reference | 12 | Reference | 26 | Reference | 2 | --- | 5 | Reference |
| 25.25–33.43 | 11 | 0.6 (0.3,1.3) | 18 | 1.5 (0.7,3.1) | 17 | 0.6 (0.3,1.2) | 3 | NC | 3 | 0.6 (0.1,2.5) | |
| 33.44–44.08 | 18 | 1.0 (0.5,2.0) | 11 | 0.9 (0.4,2.0) | 32 | 1.2 (0.7,2.1) | 5 | NC | 1 | NC | |
| 44.09–95.32 | 17 | 0.9 (0.4,1.8) | 22 | 1.9 (0.9,3.9) | 24 | 0.9 (0.5,1.6) | 6 | NC | 8 | 1.6 (0.5,5.0) | |
| PM2.5 (μg/m3) | 3.57–10.93 | 8 | Reference | 7 | Reference | 14 | Reference | 2 | --- | 3 | Reference |
| 10.94–14.82 | 16 | 1.8 (0.8,4.5) | 15 | 2.2 (0.9,5.7) | 22 | 1.6 (0.8,3.2) | 6 | NC | 3 | 1.0 (0.2,5.1) | |
| 14.83–26.12 | 15 | 1.8 (0.7,4.5) | 18 | 2.6 (1.1,6.5) | 23 | 1.6 (0.8,3.2) | 2 | NC | 5 | 1.6 (0.4,7.0) | |
| 26.13–66.29 | 12 | 1.4 (0.6,3.6) | 10 | 1.5 (0.5,4.0) | 22 | 1.5 (0.7,3.1) | NC | 6 | 1.9 (0.5,8.0) | ||
| O3 8-hour maximum (ppb) | 10.49–29.05 | 16 | Reference | 12 | Reference | 25 | Reference | 2 | --- | 4 | Reference |
| 29.06–46.94 | 19 | 1.2 (0.6,2.4) | 21 | 1.7 (0.8,3.6) | 25 | 1.0 (0.6,1.8) | 3 | NC | 6 | 1.5 (0.4,5.4) | |
| 46.95–62.64 | 10 | 0.6 (0.3,1.4) | 17 | 1.4 (0.6,3.0) | 25 | 1.0 (0.6,1.9) | 2 | NC | 6 | 1.6 (0.4,5.7) | |
| 62.65–91.92 | 18 | 1.1 (0.5,2.3) | 13 | 1.2 (0.5,2.7) | 25 | 1.0 (0.6,1.8) | 8 | NC | 1 | NC | |
| Traffic densityc | 0 | 18 | Reference | 27 | Reference | 28 | Reference | 4 | Reference | 4 | Reference |
| 1–5031 | 13 | 1.0 (0.5,2.2) | 9 | 0.6 (0.3,1.3) | 24 | 1.3 (0.7,2.3) | 4 | 1.6 (0.4,6.5) | 2 | NC | |
| 5032–16717 | 19 | 1.4 (0.7,2.9) | 19 | 1.2 (0.6,2.2) | 22 | 1.1 (0.6,2.0) | 4 | 1.6 (0.4,6.5) | 3 | 1.2 (0.3,5.5) | |
| 16718–135991 | 8 | 0.6 (0.2,1.4) | 4 | 0.3 (0.1,0.8) | 21 | 1.1 (0.6,2.0) | 2 | NC | 5 | 2.0 (0.5,7.6) | |
| Exposure levelsb | Atrioventricular septal defects | Total anomalous pulmonary venous return | Hypoplastic left heart syndrome | Coarctation of the aorta | Aortic stenosis | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | ||
| CO (ppm) | 0.13–0.39 | 4 | Reference | 5 | Reference | 13 | Reference | 13 | Reference | 6 | Reference |
| 0.40–0.52 | 3 | 0.7 (0.2,3.4) | 4 | 0.8 (0.2,3.3) | 11 | 0.8 (0.4,1.9) | 15 | 1.1 (0.5,2.5) | 2 | NC | |
| 0.53–0.71 | 4 | 0.9 (0.2,3.9) | 2 | NC | 13 | 1.0 (0.5,2.3) | 16 | 1.2 (0.6,2.7) | 10 | 1.6 (0.6,4.6) | |
| 0.72–1.37 | 1 | NC | 3 | 0.6 (0.1,2.7) | 11 | 0.7 (0.3,1.7) | 12 | 0.9 (0.4,2.1) | 2 | NC | |
| NO (ppb) | 0.69–4.14 | 3 | Reference | 7 | Reference | 12 | Reference | 15 | Reference | 4 | Reference |
| 4.15–8.15 | 2 | NC | 4 | 0.6 (0.2,2.1) | 13 | 1.2 (0.5,2.7) | 20 | 1.3 (0.7,2.7) | 5 | 1.3 (0.3,5.0) | |
| 8.16–20.19 | 4 | 1.1 (0.2,5.3) | 3 | 0.5 (0.1,1.8) | 14 | 1.1 (0.5,2.6) | 17 | 1.1 (0.5,2.4) | 8 | 1.8 (0.5,6.2) | |
| 20.20–67.34 | 4 | 1.2 (0.3,5.6) | 5 | 0.7 (0.2,2.4) | 14 | 1.2 (0.5,2.6) | 18 | 1.2 (0.6,2.5) | 6 | 1.4 (0.4,5.2) | |
| NO2 (ppb) | 2.40–13.36 | 3 | Reference | 5 | Reference | 17 | Reference | 17 | Reference | 7 | Reference |
| 13.37–16.81 | 4 | 1.2 (0.3,5.6) | 10 | 2.1 (0.7,6.3) | 17 | 1.0 (0.5,2.1) | 18 | 1.1 (0.5,2.1) | 7 | 1.0 (0.3,2.8) | |
| 16.82–20.53 | 4 | 1.1 (0.2,5.1) | 2 | NC | 14 | 0.9 (0.4,1.9) | 22 | 1.3 (0.7,2.6) | 7 | 0.9 (0.3,2.6) | |
| 20.54–38.94 | 3 | 1.0 (0.2,4.9) | 5 | 1.1 (0.3,3.7) | 13 | 0.7 (0.3,1.6) | 21 | 1.3 (0.6,2.5) | 5 | 0.6 (0.2,2.0) | |
| PM10 (μg/m3) | 7.90–25.24 | 2 | -- | 6 | Reference | 15 | Reference | 16 | Reference | 7 | Reference |
| 25.25–33.43 | 6 | NC | 8 | 1.3 (0.4,3.8) | 22 | 1.5 (0.7,2.9) | 14 | 0.8 (0.4,1.8) | 6 | 0.8 (0.3,2.4) | |
| 33.44–44.08 | 5 | NC | 6 | 1.0 (0.3,3.2) | 12 | 0.8 (0.4,1.8) | 22 | 1.4 (0.7,2.7) | 9 | 1.1 (0.4,2.9) | |
| 44.09–95.32 | 1 | NC | 4 | 0.7 (0.2,2.5) | 11 | 0.7 (0.3,1.7) | 23 | 1.4 (0.7,2.8) | 4 | 0.5 (0.1,1.8) | |
| PM2.5 (μg/m3) | 3.57–10.93 | 4 | Reference | 4 | Reference | 14 | Reference | 13 | Reference | 3 | Reference |
| 10.94–14.82 | 2 | NC | 4 | 1.0 (0.3,4.2) | 10 | 0.8 (0.3,1.8) | 16 | 1.2 (0.6,2.7) | 9 | 3.1 (0.8,12.0) | |
| 14.83–26.12 | 3 | 0.7 (0.1,3.1) | 9 | 2.2 (0.7,7.4) | 21 | 1.6 (0.8,3.3) | 14 | 1.0 (0.5,2.2) | 7 | 2.1 (0.5,8.4) | |
| 26.13–66.29 | 4 | 0.8 (0.2,3.6) | 4 | 1.0 (0.3,4.2) | 12 | 0.9 (0.4,2.0) | 16 | 1.2 (0.6,2.6) | 4 | 1.2 (0.3,5.4) | |
| O3 8-hour maximum (ppb) | 10.49–29.05 | 5 | Reference | 3 | Reference | 19 | Reference | 17 | Reference | 6 | Reference |
| 29.06–46.94 | 4 | 0.9 (0.2,3.3) | 8 | 2.6 (0.7,10.1) | 16 | 0.8 (0.4,1.6) | 22 | 1.3 (0.7,2.5) | 9 | 1.6 (0.5,4.6) | |
| 46.95–62.64 | 2 | NC | 7 | 2.4 (0.6,9.5) | 13 | 0.6 (0.3,1.3) | 15 | 0.9 (0.4,1.9) | 8 | 1.5 (0.5,4.4) | |
| 62.65–91.92 | 3 | 0.6 (0.1,2.6) | 5 | 1.7 (0.4,7.0) | 13 | 0.7 (0.3,1.5) | 23 | 1.4 (0.7,2.6) | 3 | 0.6 (0.1,2.4) | |
| Traffic densityc | 0 | 8 | --- | 6 | Reference | 14 | Reference | 22 | Reference | 10 | Reference |
| 1–5031 | 1 | NC | 3 | 0.7 (0.2,2.9) | 14 | 1.5 (0.7,3.3) | 19 | 1.3 (0.7,2.4) | 5 | 0.9 (0.3,2.7) | |
| 5032–16717 | 2 | NC | 9 | 2.1 (0.7,6.0) | 15 | 1.6 (0.7,3.4) | 18 | 1.2 (0.6,2.4) | 4 | 0.7 (0.2,2.3) | |
| 16718–135991 | 2 | NC | 3 | 0.7 (0.2,2.9) | 13 | 1.6 (0.7,3.5) | 13 | 0.9 (0.4,1.8) | 5 | 0.9 (0.3,2.8) | |
| Exposure levelsb | Pulmonary atresia | Tricuspid atresia | Pulmonary valve stenosis | Ventricular septal defects - perimembranous | Ventricular septal defects - muscular | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | ||
| CO (ppm) | 0.13–0.39 | 4 | Reference | 5 | Reference | 14 | Reference | 28 | Reference | 16 | Reference |
| 0.40–0.52 | 6 | 1.5 (0.4,5.4) | 4 | 0.9 (0.2,3.4) | 13 | 0.9 (0.4,2.1) | 19 | 0.7 (0.4,1.3) | 9 | 0.6 (0.3,1.5) | |
| 0.53–0.71 | 1 | NC | 1 | NC | 11 | 0.8 (0.3,1.7) | 18 | 0.6 (0.3,1.2) | 10 | 0.6 (0.3,1.5) | |
| 0.72–1.37 | 7 | 1.7 (0.5,6.0) | 2 | NC | 8 | 0.6 (0.2,1.4) | 15 | 0.5 (0.3,1.0) | 6 | 0.4 (0.2,1.1) | |
| NO (ppb) | 0.69–4.14 | 2 | --- | 5 | Reference | 14 | Reference | 23 | Reference | 15 | Reference |
| 4.15–8.15 | 6 | NC | 4 | 0.8 (0.2,3.2) | 11 | 0.8 (0.3,1.8) | 19 | 0.8 (0.4,1.5) | 8 | 0.6 (0.2,1.3) | |
| 8.16–20.19 | 4 | NC | 5 | 1.0 (0.3,3.6) | 12 | 0.8 (0.4,1.9) | 22 | 0.9 (0.5,1.7) | 13 | 0.9 (0.4,2.0) | |
| 20.20–67.34 | 6 | NC | 2 | NC | 13 | 0.9 (0.4,2.0) | 24 | 1.0 (0.5,1.8) | 10 | 0.7 (0.3,1.6) | |
| NO2 (ppb) | 2.40–13.36 | 2 | --- | 5 | Reference | 15 | Reference | 25 | Reference | 14 | Reference |
| 13.37–16.81 | 6 | NC | 6 | 1.2 (0.4,4.0) | 18 | 1.2 (0.6,2.4) | 32 | 1.2 (0.7,2.2) | 16 | 1.2 (0.5,2.5) | |
| 16.82–20.53 | 6 | NC | 4 | 0.8 (0.2,3.0) | 12 | 0.8 (0.4,1.8) | 22 | 0.8 (0.5,1.6) | 7 | 0.5 (0.2,1.3) | |
| 20.54–38.94 | 5 | NC | 3 | 0.6 (0.1,2.5) | 14 | 0.9 (0.4,2.0) | 19 | 0.7 (0.4,1.4) | 11 | 0.8 (0.4,1.9) | |
| PM10 (μg/m3) | 7.90–25.24 | 2 | --- | 3 | Reference | 9 | Reference | 15 | Reference | 11 | Reference |
| 25.25–33.43 | 5 | NC | 4 | 1.3 (0.3,5.8) | 13 | 1.4 (0.6,3.5) | 28 | 1.8 (0.9,3.5) | 9 | 0.8 (0.3,2.0) | |
| 33.44–44.08 | 6 | NC | 9 | 3.0 (0.8,11.2) | 15 | 1.7 (0.7,3.9) | 32 | 2.1 (1.1,3.9) | 15 | 1.4 (0.6,3.1) | |
| 44.09–95.32 | 6 | NC | 2 | NC | 23 | 2.6 (1.2,5.7) | 21 | 1.3 (0.7,2.7) | 13 | 1.2 (0.5,2.7) | |
| PM2.5 (μg/m3) | 3.57–10.93 | 5 | Reference | 4 | Reference | 10 | Reference | 28 | Reference | 15 | Reference |
| 10.94–14.82 | 3 | 0.6 (0.1,2.4) | 4 | 0.9 (0.2,3.8) | 17 | 1.7 (0.8,3.9) | 20 | 0.7 (0.4,1.3) | 8 | 0.5 (0.2,1.3) | |
| 14.83–26.12 | 3 | 0.6 (0.1,2.4) | 1 | NC | 23 | 2.2 (1.0,4.9) | 27 | 0.9 (0.5,1.6) | 11 | 0.7 (0.3,1.5) | |
| 26.13–66.29 | 5 | 0.9 (0.3,3.3) | 5 | 1.2 (0.3,4.7) | 9 | 0.9 (0.3,2.2) | 14 | 0.5 (0.2,0.9) | 10 | 0.6 (0.3,1.5) | |
| O3 8-hour maximum (ppb) | 10.49–29.05 | 4 | Reference | 4 | Reference | 12 | Reference | 24 | Reference | 9 | Reference |
| 29.06–46.94 | 6 | 1.5 (0.4,5.6) | 5 | 1.3 (0.3,4.9) | 9 | 0.7 (0.3,1.8) | 26 | 1.1 (0.6,2.0) | 7 | 0.8 (0.3,2.2) | |
| 46.95–62.64 | 4 | 1.0 (0.2,4.2) | 4 | 1.0 (0.2,4.0) | 18 | 1.5 (0.7,3.2) | 23 | 1.0 (0.5,1.8) | 18 | 2.1 (0.9,4.9) | |
| 62.65–91.92 | 5 | 1.3 (0.3,4.9) | 5 | 1.2 (0.3,4.7) | 20 | 1.7 (0.8,3.5) | 25 | 1.1 (0.6,2.0) | 14 | 1.6 (0.7,3.8) | |
| Traffic densityc | 0 | 1 | --- | 4 | Reference | 21 | Reference | 18 | Reference | 7 | Reference |
| 1–5031 | 3 | NC | 3 | 1.1 (0.2,4.9) | 12 | 0.8 (0.4,1.8) | 28 | 2.4 (1.3,4.6) | 15 | 3.4 (1.3,8.7) | |
| 5032–16717 | 6 | NC | 5 | 1.6 (0.4,6.4) | 11 | 0.8 (0.4,1.6) | 29 | 2.4 (1.3,4.6) | 8 | 1.7 (0.6,4.8) | |
| 16718–135991 | 7 | NC | 4 | 1.3 (0.3,5.5) | 13 | 0.9 (0.4,1.9) | 18 | 1.5 (0.8,3.0) | 14 | 3.0 (1.2,7.8) | |
| Exposure levelsb | Ventricular septal defects - conov | Secundum atrial septal defects | Other atrial septal defects | Single ventricle or other complex | |||||
|---|---|---|---|---|---|---|---|---|---|
| N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | N | AOR (95% CI) | ||
| CO (ppm) | 0.13–0.39 | 4 | Reference | 38 | Reference | 6 | Reference | 5 | Reference |
| 0.40–0.52 | 4 | 1.0 (0.2,4.3) | 29 | 0.8 (0.5,1.4) | 5 | 0.8 (0.2,2.7) | 4 | 0.8 (0.2,3.1) | |
| 0.53–0.71 | 6 | 1.5 (0.4,5.5) | 29 | 0.8 (0.5,1.4) | 1 | NC | 5 | 1.0 (0.3,3.6) | |
| 0.72–1.37 | 2 | NC | 15 | 0.4 (0.2,0.8) | 2 | NC | 4 | 0.8 (0.2,3.1) | |
| NO (ppb) | 0.69–4.14 | 3 | Reference | 31 | Reference | 6 | Reference | 5 | Reference |
| 4.15–8.15 | 7 | 2.2 (0.6,8.9) | 24 | 0.8 (0.4,1.4) | 5 | 0.7 (0.2,2.5) | 7 | 1.4 (0.4,4.7) | |
| 8.16–20.19 | 2 | NC | 36 | 1.2 (0.7,2.0) | 1 | NC | 2 | NC | |
| 20.20–67.34 | 5 | 1.6 (0.4,6.8) | 32 | 1.0 (0.6,1.8) | 4 | 0.7 (0.2,2.4) | 5 | 1.0 (0.3,3.6) | |
| NO2 (ppb) | 2.40–13.36 | 5 | Reference | 35 | Reference | 3 | Reference | 7 | Reference |
| 13.37–16.81 | 3 | 0.6 (0.1,2.5) | 48 | 1.4 (0.9,2.2) | 9 | 3.0 (0.8,11.4) | 4 | 0.6 (0.2,2.1) | |
| 16.82–20.53 | 6 | 1.2 (0.3,3.9) | 29 | 0.8 (0.5,1.4) | 4 | 1.3 (0.3,5.9) | 6 | 1.0 (0.3,2.9) | |
| 20.54–38.94 | 5 | 1.0 (0.3,3.5) | 28 | 0.8 (0.5,1.4) | 2 | NC | 4 | 0.6 (0.2,2.0) | |
| PM10 (μg/m3) | 7.90–25.24 | 2 | --- | 34 | Reference | 1 | --- | 7 | Reference |
| 25.25–33.43 | 6 | NC | 41 | 1.2 (0.7,1.9) | 2 | NC | 4 | 0.6 (0.2,1.9) | |
| 33.44–44.08 | 4 | NC | 34 | 1.0 (0.6,1.7) | 8 | NC | 3 | 0.5 (0.1,1.8) | |
| 44.09–95.32 | 7 | NC | 30 | 0.9 (0.5,1.5) | 7 | NC | 7 | 1.0 (0.3,3.0) | |
| PM2.5 (μg/m3) | 3.57–10.93 | 5 | Reference | 45 | Reference | 5 | Reference | 4 | Reference |
| 10.94–14.82 | 5 | 1.0 (0.3,3.5) | 20 | 0.5 (0.3,0.8) | 3 | 0.6 (0.1,2.7) | 8 | 2.0 (0.6,6.9) | |
| 14.83–26.12 | 6 | 1.2 (0.4,4.1) | 42 | 0.9 (0.6,1.5) | 5 | 0.9 (0.3,3.3) | 3 | 0.7 (0.2,3.2) | |
| 26.13–66.29 | 1 | NC | 21 | 0.5 (0.3,0.8) | 3 | 0.6 (0.1,2.6) | 4 | 1.0 (0.2,4.0) | |
| O3 8-hour maximum (ppb) | 10.49–29.05 | 2 | --- | 39 | Reference | 3 | Reference | 5 | Reference |
| 29.06–46.94 | 5 | NC | 31 | 0.8 (0.5,1.4) | 4 | 1.4 (0.3,6.2) | 6 | 1.2 (0.4,4.1) | |
| 46.95–62.64 | 8 | NC | 39 | 1.0 (0.6,1.6) | 2 | NC | 5 | 1.0 (0.3,3.6) | |
| 62.65–91.92 | 4 | NC | 31 | 0.8 (0.5,1.4) | 9 | 3.1 (0.8,11.7) | 5 | 1.0 (0.3,3.5) | |
| Traffic densityc | 0 | 9 | Reference | 28 | Reference | 4 | Reference | 7 | Reference |
| 1–5031 | 3 | 0.5 (0.1,1.8) | 44 | 2.4 (1.4,4.0) | 6 | 2.7 (0.7,9.7) | 8 | 1.6 (0.6,4.6) | |
| 5032–16717 | 5 | 0.7 (0.2,2.1) | 28 | 1.4 (0.8,2.5) | 3 | 1.3 (0.3,6.0) | 4 | 0.8 (0.2,2.9) | |
| 16718–135991 | 2 | NC | 27 | 1.4 (0.8,2.5) | 4 | 1.7 (0.4,6.9) | 3 | 0.6 (0.2,2.5) | |
a
Analyses are adjusted for maternal race/ethnicity, education and vitamin use (for the month prior to and/or the first two months of pregnancy)
b
Pollutant levels are based on 24-hour average measurements (except ozone, which is a daytime 8-hour maximum), and then averaged over 1st and 2nd months of pregnancy and analyzed in quartiles (determined from controls)
c
Dimensionless indicator based on traffic volumes within a 300 m radius and analyzed in tertiles among non-zero values
The number of controls were as follows: CO (N=624), NO (N=697), NO2 (N=814), PM10 (N=804), PM2.5 (N=646), O3 (N=815), Traffic (N=762)
NC = not calculated