Table 2.

Comparison of uncertainties between indicators

Indicator	Indicator value€	Standard deviation£	Uncertainty¥	Relative uncertainty
CO 1h (ppm)	1.16	1.00	0.16	0.14
NOx 1h (ppm)	0.12	0.10	0.03	0.25
EC (μg/m3)	1.53	0.97	0.64	0.42
IMSIEB	1.31	0.90	0.72	0.55
IMSIEB,GV	1.17	0.96	0.80	0.68
IMSIEB,DV	1.48	0.94	0.76	0.51
PMFmob	2.94	2.30	1.11	0.38
PMFGV	1.37	1.21	0.36	0.26
PMFDV	1.57	1.65	1.05	0.67
CMBmob	2.54	1.70	2.53	1.00
CMBGV	1.34	1.15	2.00	1.48
CMBDV	1.27	1.02	1.60	1.26

Notes:

^€Average of daily values from 1999–2004;

^£For daily values from 1999–2004;

^¥Uncertainties are estimated as the RMS average $\left(\overline{{\sigma }_i}=\sqrt{\frac{1}{N}\sum {\sigma }_i^2}\right)$ of daily uncertainties from 1999–2004.