Table 2.
Particle constituent concentrations and correlations between the elemental and total mass concentrations.
| Exposure | PM2.5 | PM10 | ||||
|---|---|---|---|---|---|---|
| na | Mean ± SD | rb | n | Mean ± SD | rb | |
| Mass concentration (μg/m3) | 33,882 | 17.0 ± 4.7 | 33,882 | 26.9 ± 7.8 | ||
| Elemental concentration (ng/m3) | ||||||
| Copper (Cu) | 34,923 | 3.4 ± 2.1 | 0.43 | 34,923 | 14.0 ± 10.6 | 0.54 |
| Iron (Fe) | 34,290 | 104.0 ± 57.4 | 0.17 | 34,923 | 435.3 ± 276.0 | 0.59 |
| Potassium (K) | 34,096 | 116.7 ± 27.4 | 0.20 | 34,290 | 224.3 ± 72.2 | 0.31 |
| Nickel (Ni) | 30,430 | 1.6 ± 0.8 | 0.67 | 34,923 | 1.8 ± 1.2 | 0.71 |
| Sulfur (S) | 34,290 | 753.9 ± 129.5 | 0.84 | 34,290 | 858.1 ± 171.7 | 0.84 |
| Silicon (Si) | 34,923 | 83.1 ± 54.4 | 0.02 | 34,923 | 489.7 ± 338.1 | 0.27 |
| Vanadium (V) | 34,923 | 2.8 ± 1.2 | 0.62 | 34,923 | 3.4 ± 1.5 | 0.66 |
| Zinc (Zn) | 34,290 | 14.8 ± 4.9 | 0.60 | 34,923 | 25.1 ± 10.9 | 0.61 |
| aThe numbers of participants are smaller for particle mass concentrations than for elemental concentrations because particle mass concentrations are pregnancy averages, and in some cases the routine monitoring data used to back-extrapolate particle mass concentrations were missing. Particle constituents are annual averages, and the numbers differ among particle constituents because we could not estimate all exposures in each study area. bAll Pearson correlations had a p-value < 0.001. | ||||||