Table A1.

Correlation coefficient and metrics of low-cost sensor and governmental BAM (before calibration).

	Raw(a)	Raw(b)	Raw(c)	BAM
Raw(a)	1.000	slope = 0.837 intercept = 1.969 R${}^2$ = 0.937 MAE = 4.700	slope = 0.998 intercept = 0.003 R${}^2$ = 0.994 MAE = 1.583	slope = 0.436 intercept = 6.457 R${}^2$ = 0.416 MAE = 15.816
Raw(b)	0.987	1.000	slope = 1.163 intercept = -1.335 R${}^2$ = 0.933 MAE = 4.737	slope = 0.512 intercept = 5.732 R${}^2$ = 0.546 MAE = 11.952
Raw(c)	0.997	0.985	1.000	slope = 0.435 intercept = 6.526 R${}^2$ = 0.417 MAE = 15.712
BAM	0.919	0.916	0.918	1.000