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. Author manuscript; available in PMC: 2008 May 14.
Published in final edited form as: Environ Sci Technol. 2007 Oct 15;41(20):7152–7158. doi: 10.1021/es071041z

TABLE 1.

Background Values (μ g/m3)a

obs mean median SD
trimethylpentane 432 0.71 0.43 0.79
dimethylpentane 432 0.38 0.24 0.47
2-methylhexane 432 0.64 0.42 0.95
methylpentane 432 1.60 1.04 2.28
3-methylhexane 432 0.76 0.48 1.28
methylcyclohexane 432 0.46 0.27 0.68
hexane 161 1.70 1.01 1.86
1,3-butadiene 432 0.20 0.12 0.45
benzene 432 1.24 1.01 0.87
ethylbenzene 432 0.56 0.40 0.53
m,p-xylene 432 1.85 1.36 1.69
o-xylene 432 0.66 0.46 0.63
styrene 432 0.26 0.15 0.36
toluene 432 3.67 2.77 3.43
toluene/benzene 432 3.0 2.7 n/a
MTBE 432 0.27 0.01 0.53
acetone 345 2.62 1.75 3.07
acetaldehyde 345 2.42 2.06 2.45
formaldehyde 345 3.33 3.22 1.75
elemental carbon 432 0.83 0.57 0.77
PM2.5 427 11.67 9.30 14.63
a

The differences across locations (yard background, driver, loading dock, and mechanic shop) for all concentrations were statistically significant (p < 0.01) using Kruskal–Wallis nonparametric comparison tests.