Table 3.

Model performance metrics^* for the reference classroom in each school.

School	size	$r$	$b$	$a∕{\overline{C}}_0$	$NMSE$	$FB$	$FS$
A	PM1	0.993	0.968	0.036	0.004	0.004	−0.052
	PM2.5	0.984	0.977	0.024	0.004	0.001	−0.015
	PM10	0.948	0.893	0.109	0.010	0.001	−0.108
B	PM1	0.986	0.969	0.035	0.004	0.004	−0.035
	PM2.5	0.983	0.995	0.008	0.002	0.003	0.024
	PM10	0.933	0.831	0.174	0.012	0.005	−0.231
C	PM1	0.980	0.948	0.053	0.014	0.002	−0.064
	PM2.5	0.923	0.809	0.186	0.019	−0.006	−0.264
	PM10	0.720	0.476	0.517	0.057	−0.007	−0.784
D	PM1	0.941	0.837	0.165	0.022	0.003	−0.233
	PM2.5	0.935	0.848	0.152	0.014	0.001	−0.194
	PM10	0.900	0.797	0.204	0.012	0.001	−0.243

^*The acceptable ranges of the model performance metrics for an adequate model were $r\ge 0.9$, $0.75\le b\le 1.25$, $\mid a\mid \le 0.25{\overline{C}}_o$, $NMSE\le 0.25$, $\mid FB\mid \le 0.25$, and $\mid FS\mid \le 0.5$.