Table 6.

All months 2019, CO, NO₂, PM10, LR, ANN, RF, calibration and test set.

Pollutant, Algorithm (Input Features)	${\mathit{R}}^2$		RMSE		NRMSE
	Calibration	Test	Calibration	Test	Test
CO, LR (raw)	0.931		0.068		0.264
CO, ANN (raw)	0.927	0.927	0.070	0.070
CO, ANN (raw, RH, T)	0.945	0.943	0.061	0.063	0.244
CO, RF (raw)	0.988	0.915	0.028	0.075
CO, RF (raw, RH, T)	0.994	0.945	0.022	0.060	0.233
NO2, LR (raw)	0.793		11.980		0.455
NO2, ANN (raw)	0.809	0.797	11.610	11.913
NO2, ANN (raw, RH, T)	0.908	0.872	8.040	9.340	0.348
NO2, RF (raw)	0.967	0.762	4.817	12.860
NO2, RF (raw, RH, T)	0.986	0.894	3.162	8.543	0.325
PM10, LR (raw)	0.794		14.112		0.453
PM10, ANN (raw)	0.782	0.774	14.687	14.969
PM10, ANN (raw, RH, T)	0.910	0.850	9.482	12.121	0.389
PM10, RF (raw)	0.959	0.709	6.374	17.198
PM10, RF (raw, RH, T)	0.982	0.872	4.140	11.124	0.357