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. Author manuscript; available in PMC: 2015 Feb 9.
Published in final edited form as: Atmos Environ (1994). 2012 Sep;57:72–79. doi: 10.1016/j.atmosenv.2012.04.029

Table 2.

Descriptive summary for personal air concentrations (μg m−3).a

Compound Overall
By season
By day-of-the-week
Nb Geomean 95th% Summer Winter p-valuec Weekday Weekend p-valued
WFS
MTBE 200 2.24 ± 3.21 12.9 2.46 ± 3.28 2.03 ± 3.13 0.71 1.97 ± 3.26 2.61 ± 3.12 0.49
Benzene 187 2.24 ± 2.05 7.24 2.20 ±2.16 2.28 ± 1.96 0.64 2.34 ±2.12 2.12 ± 1.98 0.41
Hexane 181 3.46 ± 6.25 230 6.59 ± 10.1 1.95 ± 2.64 <0.01 2.28 ± 2.68 5.26 ± 10.3 0.04
Toluene 200 5.61 ± 2.56 17.4 5.48 ± 2.36 5.75 ± 2.78 0.42 6.26 ± 2.96 4.94 ± 2.05 0.09
Ethylbenzene 200 0.88 ± 2.24 3.16 0.82 ± 2.36 0.95 ± 2.11 0.26 1.00 ± 2.27 0.76 ± 2.17 0.03
m/p-xylene 200 2.58 ± 2.17 9.36 2.50 ±2.13 2.68 ± 2.22 0.45 2.90 ± 2.30 2.26 ± 1.98 0.04
o-xylene 200 0.83 ± 2.12 2.66 0.82 ± 2.09 0.83 ± 2.16 0.05 0.92 ± 2.21 0.73 ± 1.97 0.05
Styrenee 200 0.20 ± 2.25 0.78 0.14 ± 2.00 0.29 ± 2.13 N/A 0.22 ± 2.29 0.18 ± 2.18 N/A
Chloroform 173 0.55 ± 2.67 3.32 0.68 ± 2.53 0.46 ± 2.72 0.05 0.57 ± 2.79 0.54 ± 2.57 0.60
Carbon tetrachloride 173 0.50 ± 1.29 0.71 0.55 ± 1.24 0.45 ± 1.28 <0.01 0.49 ± 1.30 0.50 ± 1.28 0.84
CDS
MTBE 165 2.53 ± 2.96 17.9 2.71 ± 3.84 2.34 ± 2.02 0.62 2.54 ± 2.93 2.51 ± 3.01 0.45
Benzene 153 3.10 ± 2.23 11.5 4.30 ± 2.29 2.28 ± 1.91 <0.01 3.17 ± 2.19 3.03 ± 2.29 0.74
Hexane 139 4.88 ± 7.53 1184 12.8 ± 13.9 2.34 ± 2.32 <0.01 2.86 ± 2.43 8.27 ± 13.6 0.06
Toluene 165 5.75 ± 2.69 24.4 5.47 ± 2.90 6.07 ± 2.47 0.74 6.09 ± 2.58 5.42 ± 2.81 0.75
Ethylbenzene 165 0.98 ± 2.66 5.43 0.91 ± 2.71 1.05 ± 2.60 0.22 1.07 ± 2.30 0.89 ± 3.02 0.37
m/p-xylene 165 2.67 ± 2.86 14.9 2.52 ± 2.91 2.84 ± 2.81 0.30 2.94 ± 2.48 2.41 ± 3.25 0.38
o-xylene 165 0.87 ± 2.72 4.92 0.86 ± 2.79 0.88 ± 2.66 0.36 0.95 ± 2.49 0.80 ± 2.95 0.36
Styrenee 165 0.21 ± 2.81 1.03 0.14 ± 2.95 0.32 ± 2.20 N/A 0.22 ± 2.62 0.19 ± 3.00 N/A
Chloroform 130 0.65 ±4.18 6.95 0.86 ± 3.75 0.54 ± 4.37 0.04 0.67 ±4.10 0.63 ± 4.30 0.75
Carbon tetrachloride 130 0.45 ± 1.35 0.66 0.49 ± 1.45 0.42 ± 1.25 0.02 0.46 ± 1.30 0.44 ± 1.40 0.38
a

Data are presented in geometric mean ± geometric standard deviation.

b

Total sample size: There were a few extremely high concentrations of benzene and hexane which may be due to solvent contamination, and were not included in calculation the distribution. Measurements of chloroform and carbon tetrachloride were added in the middle of the study, and thus have smaller sample size.

c

Comparison between the arithmetic mean summer and winter concentrations, p-value of t-test based on log-transformed concentrations.

d

Comparison between the arithmetic mean weekday and weekend concentrations, p-value of t-test based on log-transformed concentrations.

e

Comparisons by season and by day-of-the-week were not conducted on styrene concentrations, as only 32% of the styrene concentrations were above detection limit.