*3.1. System Validation*

The D50 diameters at a chamber flow rate of 400 L/min were 5.07 ± 0.18 μm and 6.36 ± 0.22 μm with 40 and 160 open orifices, respectively, and 7.8 ± 0.78 μm at 200 L/min with 160 open orifices (Figure 6). To ensure correct air sampling, measurements were also made at 2" from the air exhaust of cage number three for validation purposes. The D50 values measured at 2" from air exhaust were the same (data not shown).

Data collected from two sampling ports in cage number three (2" after the particle separator and 2" before the exhaust) were used to document particle deposition at 200 L/min and 400 L/min without the particle separator. Particle deposition was the same at the two flow rates. The deposition of particles of particles <3.5 μm was less than 30%.

The presence or absence of the particle separator had no significant effect on the nanoparticle size distribution (10 nm to 1 μm) between cage number two and cage number three. Under all conditions the total concentration of nanoparticles in cage number three was 0% to 12% lower than that in cage number two (Table 1).

**Table 1.** Nanoparticles (10 nm–420 nm) total concentration difference between cages two and three.

