Table 1.

Spearman correlation coefficients between concentrations of air pollutants in Seoul, Korea in 2017.

	PM10	PM2.5	NO2	SO2	O3	CO	Temperature	Relative humidity
PM10	1.000	0.875**	0.558**	0.706**	0.119*	0.609**	−0.274**	−0.141**
PM2.5		1.000	0.658**	0.708**	0.006	0.752**	−0.229**	0.062
NO2			1.000	0.677**	−0.348**	0.845**	−0.218**	−0.012
SO2				1.000	−0.124*	0.665**	−0.413**	−0.221**
O3					1.000	−0.467**	0.512**	−0.121*
CO						1.000	−0.414**	0.070
Temperature							1.000	0.426**
Relative humidity								1.000

^* and ^** indicates p < 0.05 and p < 0.01, respectively. PM₁₀, particulate matter of 10 μm or less in diameter; PM_2.5, particulate matter of 2.5 μm or less in diameter; NO₂, nitrogen dioxide; SO₂, sulfur dioxide; O₃, ozone; CO, carbon monoxide.