Table 2. Summary of taxi drivers’ exposures under different test conditions (geometric mean, interquartile range, and percentage of change from NM).
| Mitigation | NMa | WCb | WC+HECAc |
|---|---|---|---|
| On-road PM2.5 (μg/m3) | 31 (20, 53) | 28 (20, 40) (-10%)d | 29 (24, 33) (-6%) |
| In-cabin PM2.5 (μg/m3) | 19 (15, 22) | 20 (16, 20) (5%) | 12 (10, 16) * (-37%) |
|
On-road UFP (x104 cm-3) |
2.71 (2.44, 3.02) | 2.72 (2.29, 3.46) (0%) | 2.70 (2.34, 3.55) (-0%) |
|
In-cabin UFP (x104 cm-3) |
1.40 (1.13, 1.97) | 1.33 (1.07, 1.77) (-5%) | 0.74 (0.59, 1.02) * (-47%) |
|
∑OH-NAPtrap (μg/g cr) |
4.69 (2.30, 8.96) | 3.47 (1.99, 5.38) (-26%) | 4.40 (2.50, 6.47) (-6%) |
|
∑OH-FLUtrap (μg/g cr) |
0.51 (0.29, 0.71) | 0.40 (0.30, 0.74) (-22%) | 0.48 (0.33, 0.60) (-6%) |
|
∑OH-PHEtrap (μg/g cr) |
0.15 (0.08, 0.24) | 0.12 (0.07, 0.20) (-20%) | 0.18 (0.14, 0.20) (20%) |
|
1-OH-PYRtrap (μg/g cr) |
0.05 (0.02, 0.10) | 0.05 (0.02, 0.10) (0%) | 0.07 (0.05, 0.10) (40%) |
|
Pre-test MDA (μg/g cr) |
20.80 (20.53, 54.18) | 10.74 (9.23, 40.95) (-48%) | 27.14 (13.49, 56.39) (30%) |
|
Post-test MDA (μg/g cr) |
31.91 (22.78, 47.25) | 31.73 (22.87, 43.90) (-1%) | 23.68 (9.99, 55.37) (-17%) |
a. No mitigation
b. Window closed
c. High efficiency cabin air filter
d. Numbers in parenthesis indicate percentage of change from NM.
* indicate significance of paired t-test (p < 0.05) compared with NM.