Table 6.

Linear regression analysis of stationary area measurements with inhalable cobalt as the independent variable and other particle fractions as dependent^a,b

Aerosol fraction (Dependent; Independent)	Regression			Prediction
	β (p)	95% CI (β)	r 2	Predicted concentrationc	95% CI (y)d
PM2.5Co (S); Inhalable Co (S)	0.345(0.002)	0.139–0.552	0.332	0.0000726	0.0000112–0.0000495
PM10Co (S); Inhalable Co (S)	0.831(<0.001)	0.591–1.07	0.680	0.00557	0.000599–0.0518
Particle surface area (mean) (S); Inhalable Co (S)	−0.201(0.037)	−0.387 to (−0.014)	0.221	2.89	0.770–10.8
Particle number (mean) (S); Inhalable Co (S)	−0.040(0.509)	−0.164 to 0.084	0.019	2276	742–6970

β, regression coefficient; r ², correlation coefficient; S, stationary area measurements; 95% CI (β), 95% confidence interval for β.

^aAll data ln-transformed, except predicted concentrations presented in original units.

^b n = 28, except for particle surface area (n = 22) and particle number (n = 27).

^cPredicted concentration = predicted individual concentration for inhalable cobalt 0.02mg m⁻³.

^dCI (y) = 95% confidence interval for predicted dependent metrics, individual concentrations.