Table 3.
Exposure to ambient PM2.5 and O3 and traffic at the residential address during pregnancy.
| Exposure | n | median (25th – 75th percentiles) |
|---|---|---|
| Average PM2.5 (µg/m3) a | ||
| Trimester 1 | 671 | 7.5 (6.9 – 8.2) |
| Trimester 2 | 663 | 7.4 (6.8 – 8.0) |
| Trimester 3 | 695 | 7.3 (6.8 – 8.1) |
| Full pregnancy | 711 | 7.5 (7.0 – 7.9) |
|
| ||
| Average 8-hr max O3 (ppb) a | ||
| Trimester 1 | 718 | 41.8 (32.7 – 53.2) |
| Trimester 2 | 718 | 42.7 (34.1 – 52.2) |
| Trimester 3 | 717 | 46.2 (35.3 – 54.0) |
| Full pregnancy | 718 | 44.0 (41.0 – 46.8) |
|
| ||
| Distance to nearest highway (m) | 738 | 866 (404 – 1689) |
|
| ||
| Distance to nearest non-highway major roadway (m) | 738 | 153 (68 – 308) |
|
| ||
| Traffic density on major roads (vehicles*km/day) | ||
| 150m buffer | 725 | 437 (0 – 2846) |
| 250m buffer | 725 | 3276 (0 – 9494) |
| 500m buffer | 725 | 23059 (9478 – 42551) |
| 1000m buffer | 725 | 111625 (64368 – 160575) |
Abbreviations: PM2.5 = fine particulate matter; O3 = ozone.
a
Sample sizes differ due to missing monitoring data. Averages from a given monitor were included if at least 75% of the daily air pollution concentrations throughout the specified pregnancy period were non-missing.