Figure 4

Regional deposition of inhaled IrNP determined either immediately (0 h) or 24 h after a 1-h inhalation exposure. The fast cleared fraction (A) estimates the airway deposition fraction including head airways. Regional deposition is given relative to the totally deposited aerosol. The difference between 0 h and 24 h relates to the fact that fast clearance is not finished after the 1-h inhalation. Therefore, only the 24-h values are to be considered. No significant difference between the two animal groups. Peripheral lung retention (B) represents long-term retained IrNP. The difference between 0 h and 24 h relates to the fact that fast clearance is not finished after the 1-h inhalation, adding to lung retention. Therefore, only the 24-h values are to be considered for IrNP retention in the peripheral lungs. No significant difference between the two animal groups.