Table 3.

Spearman correlation coefficients between different air pollutants

	PM10	PM2.5	NO2	SO2	CO	O3-8 h max
PM10	1	0.90**	0.75**	0.61**	0.75**	−0.10**
PM2.5		1	0.74**	0.57**	0.87**	−0.15**
NO2			1	0.69**	0.80**	−0.42**
SO2				1	0.69**	−0.38**
CO					1	−0.42**
O3-8 h max						1

Note:

^**P<0.01.

Abbreviations: CO, carbon monoxide; NO₂, nitrogen dioxide; O₃, ozone; O₃-8 h max, 8-hour mobile mean maximum; PM_2.5, particulate matter ≤2.5 µm in aerodynamic diameter; PM₁₀, particulate matter ≤10 µm in aerodynamic diameter; SO₂, sulfur dioxide.