Table 2 Distribution of air pollution concentrations and meteorological parameters.

Variables	Mean	SD	Minimum	Q1	Median	Q3	Maximum
SO2, μg/m3	6.9	7.5	0	2	4	9	65
NOx, μg/m3	39.6	14.3	6	30	39	48	126
O3, μg/m3	29.9	21.5	0	12	26	44	115
CO, μg/m3	683.5	468.8	0	376	590	889	4014
PM10, μg/m3*	21.1	11.3	2	13	19	27	103
Minimum temperature, °C	6.9	6.4	–14.5	2	7.1	11.9	23.1
Maximum temperature, °C	16	8.5	–6.7	9.6	15.9	22.5	39.3
Maximum humidity, %	93.6	6.8	51	91	96	98	100
Minimum humidity, %	55.9	18.7	12	41	54	70	100

Q1, first quartile value; Q3, third quartile value.

*From 1994 to 2004.