Table 4.
Area, number of monitors, and ratios τu2/σx2 for the 7 chemical components and 20 US counties, 2000–2006
| US county | Area (km2) | Number of monitors |
τu2/σx2 |
||||||
| Sulfate | Nitrate | Silicon | EC | OCM | Sodium ion | Ammonium | |||
| Los Angeles, CA | 10 518 | 1 | 1.08 | 1.08 | 2.39 | 4.95 | 2.40 | 13.92 | 1.21 |
| Cook, IL | 2449 | 4 | 0.22 | 0.20 | 0.50 | 1.05 | 0.49 | 3.00 | 0.23 |
| Maricopa, AZ | 23 836 | 5 | 0.68 | 0.84 | 1.08 | 1.66 | 1.05 | 3.76 | 0.74 |
| San Diego, CA | 10 878 | 2 | 0.59 | 0.60 | 1.24 | 2.57 | 1.25 | 7.13 | 0.64 |
| Queens, NY | 283 | 1 | 0.53 | 0.42 | 1.36 | 3.08 | 1.38 | 9.15 | 0.56 |
| Dallas, TX | 2278 | 2 | 0.41 | 0.38 | 0.93 | 2.00 | 0.95 | 5.70 | 0.45 |
| Wayne, MI | 1591 | 3 | 0.28 | 0.29 | 0.64 | 1.34 | 0.64 | 3.76 | 0.33 |
| King, WA | 5506 | 6 | 0.62 | 0.71 | 0.88 | 1.29 | 0.86 | 2.74 | 0.64 |
| Santa Clara, CA | 3343 | 2 | 0.65 | 0.70 | 1.30 | 2.49 | 1.34 | 6.48 | 0.71 |
| Broward, FL | 3122 | 1 | 0.89 | 0.83 | 1.99 | 4.15 | 2.01 | 11.93 | 0.96 |
| Riverside, CA | 18 667 | 1 | 1.93 | 2.12 | 3.53 | 6.63 | 3.52 | 17.34 | 2.08 |
| New York, NY | 59 | 1 | 0.49 | 0.38 | 1.18 | 2.68 | 1.19 | 7.84 | 0.49 |
| Philadelphia, PA | 350 | 3 | 0.17 | 0.14 | 0.45 | 1.07 | 0.47 | 3.12 | 0.18 |
| Cuyahoga, OH | 1187 | 2 | 0.47 | 0.45 | 1.00 | 2.06 | 1.00 | 5.57 | 0.50 |
| Clark, NV | 20 488 | 2 | 1.04 | 1.12 | 1.94 | 3.52 | 1.94 | 8.61 | 1.15 |
| Bronx, NY | 109 | 3 | 0.20 | 0.17 | 0.44 | 0.95 | 0.44 | 2.67 | 0.20 |
| Allegheny, PA | 1891 | 3 | 0.29 | 0.26 | 0.64 | 1.34 | 0.63 | 3.75 | 0.32 |
| Sacramento, CA | 2501 | 2 | 0.46 | 0.42 | 0.99 | 2.12 | 1.04 | 5.89 | 0.51 |
| Hennepin, MN | 1442 | 2 | 0.67 | 0.66 | 1.30 | 2.35 | 1.26 | 6.00 | 0.71 |
| Franklin, OH | 1398 | 1 | 0.71 | 0.64 | 1.71 | 3.73 | 1.73 | 10.85 | 0.78 |