Table 2—

Pearson correlation coefficients among environmental variables, Rome 1995–1997

	Temperature	Humidity	Particles	SO₂	CO	NO₂
Whole year
Humidity %	−0.21
Particles µg·m⁻³	0.00	0.07
SO₂ µg·m⁻³	−0.61	−0.05	0.25
NO₂ µg·m⁻³	−0.42	0.38	0.35	0.56
CO mg·m⁻³	0.04	−0.28	0.35	0.33	0.31
O₃ µg·m⁻³	0.68	−0.55	−0.01	−0.35	−0.57	0.19
Cold season (October–March)
Humidity %	0.25
Particles µg·m⁻³	0.16	0.02
SO₂ µg·m⁻³	−0.51	−0.23	0.26
NO₂ µg·m⁻³	0.10	0.33	0.49	0.37
CO mg·m⁻³	0.04	−0.21	0.50	0.40	0.41
O₃ µg·m⁻³	0.10	−0.59	−0.02	−0.12	−0.44	0.19
Warm season (April–September)
Humidity %	−0.20
Particles µg·m⁻³	0.10	0.07
SO₂ µg·m⁻³	−0.27	−0.34	0.25
NO₂ µg·m⁻³	−0.21	0.19	0.21	0.44
CO mg·m⁻³	−0.15	−0.31	0.25	0.68	0.59
O₃ µg·m⁻³	0.56	−0.49	0.11	0.06	−0.38	0.13

suspended particles with a cut-off point at ∼13 µm
SO₂: sulphur dioxide
CO: carbon monoxide
NO₂: nitrogen dioxide
O₃: ozone