Table 3.

Model fit and 10-fold cross validation between the predicted and the measured samples.

	Model R 2
Model	Fixed	Mixed	RMSE (µg m−3)	MAE (µg m−3)	R 2 CV (%)
NO	0.66	0.79	21.7	14.9	0.78
NO2	0.62	0.88	14.6	10.8	0.80