Table 4.
Associations between preterm births and indicators of traffic-related pollution at fine geographic scale in California, by geocoding accuracy.
| Air pollution indicator | All subjects (regardless of geocoding accuracy of maternal residences) | Subjects with maternal residences geocoded at the tax parcel level | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Cases (n) | Controls (n) | IQR | Adjusted OR (95% CI)a | p-Value | Cases (n) | Controls (n) | IQR | Adjusted OR (95% CI)a | p-Value | |
| CALINE4 modeled concentrations (years 2000–2008) | ||||||||||
| UFP | 397,047 | 741,023 | 6,480 | 0.994 (0.988, 1.000) | 0.04 | 212,010 | 216,885 | 6,770 | 1.028 (1.021, 1.036) | < 0.01 |
| CO | 397,047 | 741,023 | 58.79 | 1.003 (0.996, 1.009) | 0.44 | 212,010 | 216,885 | 64.65 | 1.044 (1.035, 1.053) | < 0.01 |
| NOx | 397,047 | 741,023 | 5.97 | 1.005 (0.999, 1.011) | 0.08 | 212,010 | 216,885 | 6.47 | 1.034 (1.026, 1.042) | < 0.01 |
| Traffic density (within buffers of different sizes, years 2000–2008) | ||||||||||
| 50-m buffer | 427,642 | 829,442 | 0.968 (0.940, 0.996) | 0.03 | 232,775 | 250,195 | 1.063 (1.013, 1.117) | 0.01 | ||
| 150-m buffer | 427,642 | 829,442 | 0.987 (0.972, 1.002) | 0.09 | 232,775 | 250,195 | 1.048 (1.026, 1.072) | < 0.01 | ||
| 250-m buffer | 427,642 | 829,442 | 0.964 (0.950, 0.979) | < 0.01 | 232,775 | 250,195 | 1.011 (0.990, 1.033) | 0.29 | ||
| 350-m buffer | 427,642 | 829,442 | 0.962 (0.947, 0.978) | < 0.01 | 232,775 | 250,195 | 1.012 (0.989, 1.035) | 0.31 | ||
| Distance to roadways (years 2000–2008) | ||||||||||
| < 50 m | 427,762 | 829,871 | 0.983 (0.975, 0.991) | < 0.01 | 232,863 | 250,398 | 0.996 (0.983, 1.009) | 0.54 | ||
| < 100 m | 427,762 | 829,871 | 0.991 (0.984, 0.998) | < 0.01 | 232,863 | 250,398 | 1.009 (0.998, 1.020) | 0.11 | ||
| < 150 m | 427,762 | 829,871 | 0.988 (0.980, 0.996) | 0.01 | 232,863 | 250,398 | 1.013 (1.002, 1.023) | 0.02 | ||
| < 200 m | 427,762 | 829,871 | 0.981 (0.973, 0.990) | < 0.01 | 232,863 | 250,398 | 1.003 (0.992, 1.014) | 0.63 | ||
| Unit is parts per billion for gaseous pollutants. aOdds ratios were estimated using conditional logistic regression models, adjusted for race/ethnicity and educational level using categorical variables and for maternal age and median household income at census block–group level using polynomial functions. For estimated pollutant concentrations, odds ratios are expressed per interquartile range. For traffic density, they are expressed per 10,000 vehicles per day per meter. For distance to roadways, they compare births within the stated distance to those outside that distance. | ||||||||||