| Sampling Date | N | Eight Hours Mean (SD) | Twenty-four Hours Mean (SD) | Twenty-four hours Min Max | |
| Year 1999 |
|
|
|
|
|
| Mar. 27 | 84 | 2.09 (2.19) | 3.38 (3.53) | 0.0 | 20.7 |
| May 1 | 84 | 4.30 (3.61) | 7.12 (6.30) | 0.2 | 33.0 |
| June 11 | 84 | 5.91 (4.11) | 8.55 (6.18) | 0.0 | 29.0 |
| Aug. 27 | 84 | 10.37 (5.11) | 16.34 (9.53) | 1.5 | 41.0 |
| Nov. 12 | 84 | 3.90 (3.23) | 6.40 (5.48) | 0.3 | 33.2 |
| Year 2000 |
|
|
|
|
|
| Mar. 25 | 84 | 5.44 (4.43) | 8.77 (7.01) | 0.2 | 28.3 |
| May 6 | 84 | 6.26 (4.74) | 10.22 (7.91) | 0.0 | 32.8 |
| June 7 | 84 | 5.97 (4.69) | 10.26 (8.41) | 0.0 | 34.0 |
| Sept. 15 | 83* | 8.47 (4.99) | 13.33 (8.54) | 0.0 | 35.0 |