Calculating Respiratory Deposition of Phi6 Virus

The Phi6 dose inhaled by the experiment subjects was calculated from the particle size-resolved APS data using the assumption of 1.6 viruses per particle and by using a lung deposition model presented by the International Commission on Radiological Protection [29 ]. According to ICRP, the deposition efficiency of different sized particles to the human respiratory system can be estimated using the function curves shown in Fig. 2 [29 ]. These curves describe the fraction (%) of particles, which deposit to the head airways, tracheobronchial, and alveolar region (4) of a human respiratory system as a function of particle size. The total deposition efficiency is the sum of the regional depositions. Mathematical equations for these functions have also been presented by Hinds [30 ] (1999). The impact of using a respirator (FFP2 or FFP3) was also considered. The dose inhaled was calculated as follows: $Inhalationdose=\sum _{i=1}^{52}\left((1-{Resp}_{leak}\right){*V}_{inhaled}*(1-{Resp}_{flt})*n_i*1.6*D_{eff,i})+({Resp}_{leak}*V_{inhaled}*n_i*1.6*D_{eff,i})$ where ${Resp}_{leak}$ is the respirator internal leak, $V_{inhaled}$ is the inhaled (or sampled) air volume, ${Resp}_{flt}$ is the respirator filtration efficiency, $n_i$ is the particle number concentration of the ith size bin and $D_{eff,i}$ is the deposition efficiency of particles of ith size bin. The APS measured particle number concentrations in 52 size bins spaced logarithmically from 0.5 to 20 μm.Fig. 2

Respiratory deposition efficiency of 0.001–10 μm sized particles (ICRP, 1994) [29 ].

Fig. 2