Table 4

Determinants of PM_2.5 indoor concentrations in home (n=48) and office (n=42) not exposed to tobacco smoke; multiple linear regression

	In-home concentration					In-office concentration
Independent variable	Coeff	Std err	Std reg coeff	p	R²*	Coeff	Std err	Std reg coeff	p	R²*
*R² from the stepwise regression model.
Ambient concentration	0.499	0.118	0.52	<0.001	0.265	0.407	0.196	0.32	0.04	0.154
Person density	118.015	62.337	0.24	0.02	0.334	−61.982	28.781	−0.32	0.04	0.199
Traffic proximity	1.676	0.877	0.23	0.03	0.391