Table 2.
Summary of statistics (mean ± SD) for PM10–2.5 mass (μg/m3) and chemical component (ng/m3)a concentrations in each sampling city by season.
| City and seasonb | n | Total mass | Copper | Phosphorus | Silicon | Zinc |
|---|---|---|---|---|---|---|
| aSilicon values in μg/m3. bAll sampling was conducted in 2009. Chicago: winter (April 8–22), summer (August 20–September 3); St. Paul: winter (January 17–31), summer (May 27–June 10); Winston-Salem: winter (February 25–March 11), summer (July 6–20). bThirty-two for the four species. cSixty-three for the four species. | ||||||
| Chicago, IL | ||||||
| Winter | 33b | 5.54 ± 1.98 | 7.83 ± 3.32 | 13.64 ± 6.00 | 0.43 ± 0.11 | 23.74 ± 18.36 |
| Summer | 31 | 5.94 ± 2.09 | 7.10 ± 4.37 | 17.87 ± 3.87 | 0.31 ± 0.16 | 25.87 ± 22.85 |
| Pooled | 64c | 5.73 ± 2.03 | 7.47 ± 3.86 | 15.72 ± 5.46 | 0.37 ± 0.15 | 24.79 ± 20.55 |
| St. Paul, MN | ||||||
| Winter | 25 | 3.34 ± 2.22 | 4.01 ± 1.23 | 8.20 ± 4.68 | 0.27 ± 0.04 | 5.23 ± 3.42 |
| Summer | 34 | 6.66 ± 3.33 | 2.77 ± 1.69 | 18.67 ± 5.44 | 0.72 ± 0.19 | 5.55 ± 7.03 |
| Pooled | 59 | 5.25 ± 3.33 | 3.29 ± 1.63 | 14.23 ± 7.29 | 0.53 ± 0.27 | 5.42 ± 5.74 |
| Winston-Salem, NC | ||||||
| Winter | 35 | 3.46 ± 1.21 | 2.57 ± 1.23 | 12.83 ± 3.70 | 0.41 ± 0.09 | 3.31 ± 2.67 |
| Summer | 28 | 3.83 ± 1.64 | 2.57 ± 1.46 | 25.90 ± 5.71 | 0.35 ± 0.11 | 2.76 ± 1.95 |
| Pooled | 63 | 3.63 ± 1.42 | 2.57 ± 1.33 | 18.64 ± 8.04 | 0.38 ± 0.10 | 3.07 ± 2.37 |