Figure 2
From: Thoracic and respirable particle definitions for human health risk assessment
Thoracic fraction, i.e., particle penetration through the extrathoracic region, P(ET), as a function of breathing route. Penetration data are with respect to particle diameter as a function of the fraction of air inhaled through the mouth (Fm) in an adult male engaged in light exercise relative to particles entering the respiratory tract. Curves are for the Fm of 0.00, 0.25, 0.50, 0.75, and 1.00 as indicated on the figure. Horizontal red line highlights 50% penetration.