Table 3.

Regression Results. Estimated effect of each of the predictors on the mean log transformed pollutant concentration, using both the independent and spatially correlated error models. Standard errors of the estimates are shown in parenthesis. Estimates that are significantly different from 0 (p-value less than 0.05) are marked with *.

	β 0 (intercept)		β 1 (calm)		β 2 (railyard)		β 3 (downwind)		β 4 (distance)
	Independent	Spatial	Independent	Spatial	Independent	Spatial	Independent	Spatial	Independent	Spatial
NO	0.76 (0.02) *	0.66 (0.09) *	0.41 (0.03) *	0.53 (0.19) *	0.66 (0.05) *	0.59 (0.08) *	0.11 (0.04) *	0.37 (0.09) *	−0.90 (0.06) *	−0.79 (0.08) *
NO2	2.06 (0.03) *	1.85 (0.1) *	0.46 (0.04) *	0.71 (0.22) *	0.62 (0.05) *	0.67 (0.08) *	0.21 (0.04) *	0.51 (0.09) *	−0.75 (0.07) *	−0.47 (0.09) *
NOy	2.27 (0.02) *	2.16 (0.07) *	0.39 (0.03) *	0.54 (0.15) *	0.59 (0.04) *	0.58 (0.06) *	0.17 (0.03) *	0.34 (0.07) *	−0.73 (0.05) *	−0.54 (0.07) *
BC	−0.43 (0.02) *	−0.50 (0.06) *	0.35 (0.03) *	0.38 (0.13) *	0.58 (0.04) *	0.59 (0.05) *	0.20 (0.03) *	0.38 (0.05) *	−0.4 (0.05) *	−0.32 (0.06) *
CO	5.31 (0.01) *	5.30 (0.02) *	0.12 (0.01) *	0.19 (0.05) *	0.02 (0.01)	0.04 (0.02) *	0.03 (0.01) *	0.02 (0.02)	0.05 (0.01) *	0.09 (0.02) *
Ext.	3.30 (0.01) *	3.25 (0.06) *	0.34 (0.02) *	0.40 (0.13) *	0.21 (0.03) *	0.24 (0.04) *	0.09 (0.02) *	0.16 (0.04) *	−0.18 (0.04) *	−0.22 (0.04) *
PN	8.42 (0.01) *	8.38 (0.04) *	0.15 (0.02) *	0.19 (0.08) *	0.27 (0.02) *	0.24 (0.03) *	0.002 (0.02)	0.13 (0.04) *	−0.30 (0.03) *	−0.30 (0.04) *
Benz.	−0.85 (0.01) *	−0.84 (0.02) *	0.13 (0.01) *	0.14 (0.03) *	0.03 (0.02) *	0.01 (0.03)	0.01 (0.01)	−0.01 (0.03)	−0.06 (0.02) *	−0.07 (0.04)
Tol.	−1.31 (0.01) *	−1.23 (0.05) *	0.30 (0.02) *	0.32 (0.07) *	0.24 (0.03) *	0.12 (0.06) *	−0.01 (0.02)	−0.10 (0.07)	0.12 (0.04) *	0.04 (0.09)
Acetal.	0.70 (<0.01) *	0.73 (0.02) *	0.13 (0.01) *	0.13 (0.03) *	0.10 (0.01) *	0.03 (0.02)	0.08 (0.01) *	0.05 (0.02) *	−0.06 (0.01) *	−0.14 (0.03) *