Table 2 Pearson’s correlation coefficients for square root of daily PB-PAH exposures and key predictor variables

N

180

180

180

180

180

180

180

180

180

180

180

180

180

Mean

3.0

90.7

4.6

0.73

55.2

22.2

2.3

38.1

35796.5

163362.7

21.1

4.2

63.0

Standard deviation

1.3

7.9

5.1

0.44

18.2

7.0

2.7

80.6

30026.1

211034.8

3.2

1.7

12.4

PB-PAH SQRT^a

1.00

Indoor time (%)

−0.55***

1.00

In-vehicle time (%)

0.69***

−0.81***

1.00

Weekday (1/0)

0.16*

−0.07

0.04

1.0

Daytime (%)

0.28***

−0.22**

0.21**

−0.13

1.00

Time in rush hour (%)

0.07

−0.04

0.03

0.04

0.13

1.00

GPS speed (km/h)

0.60***

−0.74***

0.93***

−0.06

0.25***

0.01

1.00

Elevation (m)

−0.08

−0.09

0.07

−0.12

−0.03

−0.06

0.16*

1.00

Length-weighted AADT within 500 m (vehicles/day)

0.27***

0.06

−0.02

0.08

0.32***

0.03

−0.06

−0.10

1.00

Traffic density within 300 m (vehicles per day*km/km²)

0.19*

0.11

−0.07

0.06

0.31***

0.04

−0.08

−0.09

0.94***

1.00

Ambient temperature (°C)

0.09

0.06

0.09

−0.02

0.26***

−0.14

0.13

−0.04

0.09

0.07

1.00

Ambient wind speed (m/s)

0.14

−0.32***

0.17

−0.06

0.53***

0.15*

0.20**

0.07

0.06

0.05

0.07

1.00

Ambient humidity (%)

−0.11

0.02

−0.09

0.06

−0.37***

0.06

−0.13

0.02

−0.05

−0.01

−0.72***

−0.12

1.00