Table 2. Descriptive statistics and spatial differences for the 10 VOCs (µg/m3) monitored at the four local-source dominated sites in the study.
N | Mean | SD | Min | Med | Max | p-valuea | MultipleComparisonb | N | Mean | SD | Min | Med | Max | p-valuea | MultipleComparisonb | ||
Acetylene | Styrene | ||||||||||||||||
Background | 69 | 0.52 | 0.35 | 0.02 | 0.43 | 1.76 | <.0001 | A | Background | 69 | 0.07 | 0.06 | 0.02 | 0.04 | 0.34 | <.0001 | A |
Commercial | 45 | 1.76 | 1.72 | 0.34 | 1.16 | 8.22 | B | Commercial | 45 | 0.28 | 0.24 | 0.02 | 0.21 | 0.98 | B | ||
Industrial | 45 | 1.20 | 1.10 | 0.20 | 0.97 | 6.89 | B | Industrial | 45 | 0.16 | 0.11 | 0.02 | 0.13 | 0.60 | C | ||
Mobile | 50 | 1.41 | 1.27 | 0.27 | 1.11 | 6.72 | B | Mobile | 50 | 0.17 | 0.11 | 0.02 | 0.13 | 0.60 | B C | ||
Benzene | Toluene | ||||||||||||||||
Background | 69 | 0.52 | 0.22 | 0.22 | 0.48 | 1.19 | <.0001 | A | Background | 69 | 0.71 | 0.54 | 0.19 | 0.53 | 3.17 | <.0001 | A |
Commercial | 45 | 1.81 | 1.15 | 0.54 | 1.44 | 6.52 | B | Commercial | 45 | 7.98 | 6.06 | 1.06 | 6.37 | 32.4 | B | ||
Industrial | 45 | 1.11 | 0.68 | 0.35 | 0.90 | 4.16 | C | Industrial | 45 | 6.46 | 4.94 | 0.45 | 5.47 | 25.6 | B | ||
Mobile | 50 | 1.36 | 0.82 | 0.35 | 1.21 | 4.99 | B C | Mobile | 50 | 8.06 | 6.60 | 0.87 | 6.49 | 31.4 | B | ||
DCM | m,p-Xylene | ||||||||||||||||
Background | 69 | 0.33 | 0.25 | 0.03 | 0.28 | 1.60 | <.0001 | A | Background | 69 | 0.30 | 0.21 | 0.04 | 0.26 | 1.13 | <.0001 | A |
Commercial | 45 | 1.15 | 1.26 | 0.17 | 0.80 | 7.18 | B | Commercial | 45 | 4.62 | 6.99 | 0.43 | 2.39 | 40.9 | B | ||
Industrial | 45 | 1.31 | 1.46 | 0.17 | 0.70 | 6.34 | B | Industrial | 45 | 1.51 | 1.28 | 0.17 | 1.35 | 7.17 | C | ||
Mobile | 50 | 1.14 | 1.28 | 0.24 | 0.71 | 6.83 | B | Mobile | 50 | 1.45 | 1.09 | 0.26 | 1.24 | 6.82 | C | ||
EB | o-Xylene | ||||||||||||||||
Background | 69 | 0.14 | 0.08 | 0.04 | 0.13 | 0.43 | <.0001 | A | Background | 69 | 0.13 | 0.08 | 0.01 | 0.13 | 0.43 | <.0001 | A |
Commercial | 45 | 1.28 | 1.50 | 0.17 | 0.83 | 9.04 | B | Commercial | 45 | 1.20 | 1.19 | 0.17 | 0.87 | 6.65 | B | ||
Industrial | 45 | 0.53 | 0.38 | 0.09 | 0.48 | 2.22 | C | Industrial | 45 | 0.55 | 0.42 | 0.09 | 0.48 | 2.48 | C | ||
Mobile | 50 | 0.54 | 0.34 | 0.13 | 0.48 | 2.17 | C | Mobile | 50 | 0.57 | 0.40 | 0.13 | 0.48 | 2.56 | C | ||
MEK | p-DCB | ||||||||||||||||
Background | 69 | 1.08 | 1.22 | 0.07 | 0.91 | 8.09 | <.0001 | A | Background | 69 | 0.04 | 0.04 | 0.02 | 0.02 | 0.24 | <.0001 | A |
Commercial | 45 | 2.76 | 2.11 | 0.07 | 2.27 | 10.0 | B | Commercial | 31 | 0.47 | 0.24 | 0.12 | 0.42 | 1.39 | B | ||
Industrial | 45 | 2.77 | 3.06 | 0.07 | 1.77 | 14.0 | B | Industrial | 45 | 0.34 | 0.20 | 0.02 | 0.30 | 1.02 | C | ||
Mobile | 50 | 1.41 | 1.09 | 0.07 | 1.03 | 4.72 | A | Mobile | 50 | 0.30 | 0.17 | 0.06 | 0.27 | 0.78 | C |
Differences within the four sampling sites were conducted using the Kruskal-Wallis test and pairwise multiple comparison tests (Wilcoxon rank-sum test) were followed, if the difference was significant (p<0.05).
Different letters mean significant differences (p<0.0083) among the four monitoring sites.
Abbreviation in the table: DCM: Dichloromethane, EB: Ethylbenzene, MEK: Methyl Ethyl Ketone, p-DCB: p-Dichlorobenzene.