Table 3 Spearman's correlation coefficients between air pollutants and measured temperature.

City	Pollutant	PNC	PM10	CO	NO2	O3
Augsburg	PM10	0.53
	CO	0.63	0.56
	NO2	0.65	0.64	0.68
	O3*	0.26	0.43	0.10	0.38
	Temp	−0.60	0.02	−0.27	−0.02	0.49
Barcelona	PM10	0.38
	CO	0.80	0.44
	NO2	0.49	0.48	0.46
	O3	−0.35	0.01	−0.23	−0.16
	Temp	−0.66	−0.03	−0.44	−0.27	0.03
Helsinki	PM10	0.45
	CO	0.48	0.21
	NO2	0.82	0.40	0.43
	O3	0.01	0.40	0.08	0.11
	Temp	−0.51	−0.01	−0.27	−0.12	0.17
Rome	PM10	0.32
	CO	0.83	0.27
	NO2	0.68	0.47	0.57
	O3	0.03	0.13	0.02	0.31
	Temp	−0.73	0.05	−0.52	−0.25	0.41
Stockholm	PM10	0.06
	CO	0.56	0.41
	NO2	0.83	0.29	0.75
	O3	−0.01	0.59	0.20	0.19
	Temp	−0.65	0.14	−0.27	−0.33	0.11

*Correlation for 8 h O₃ during warm season (April–September).