Table 2. Mean in-vehicle exposures by commute type.

Exposure Characteristics
Commute Type (N)
Highway	36
Non-Highway	37
PM2.5 (μg·m-3) a
Highway	17.14 (6.18)
Non-Highway	11.18 (8.58)
BC (μg·m-3) a
Highway	5.33 (2.23)
Non-Highway	1.58 (1.43)
OC (μg·m-3) a
Highway	7.66 (1.98)
Non-Highway	6.07 (1.70)
WSOC (μg·m-3)
Highway	8.48 (3.75)
Non-Highway	7.95 (3.45)
PNC (#·m-3) a
Highway	34,808 (12,918)
Non-Highway	10,649 (8,147)
pb-PAH (μg·m-3) a
Highway	113.93 (30.51)
Non-Highway	65.21 (38.94)
Noise (dBA) a
Highway	68.59 (2.73)
Non-Highway	58.40 (11.23)
Aluminum (Al) (ng·m-3)
Highway	29.36 (28.67)
Non-Highway	24.37 (19.71)
Iron (Fe) (ng·m-3)
Highway	176.33 (171.19)
Non-Highway	121.55 (115.99)
Lead (Pb) (ng·m-3)
Highway	0.45 (0.45)
Non-Highway	0.92 (1.64)

Values are mean (SD), unless noted otherwise.

^adenotes p < 0.05 for Student’s t test