**5. Conclusions**

This paper describes a chamber system that can be used for airborne disease transmission studies. The system is airtight and particle size distribution through the system is satisfactory (no significant difference was found for particles <420 nm). The particle separator D50 can be modulated between 5.07 and 7.8 μm by changing the airflow. To further reduce the D50, plates with smaller holes could replace the actual hole plates of the particle separator. This would lead to more accelerated particles and, therefore, more particles being captured by the impaction plates. Ferrets can be used as models for the study of many mammalian viruses, including filovirus [18], respiratory syncytial virus [19] and Morbillivirus [20]. Therefore, the studies that can be conducted in this chamber system are not limited to influenza viruses. Moreover, this cage system can be adapted to accommodate other animals like rats or rabbits. Indeed, smaller, regular cages can be placed inside the ventilated airtight cages.

**Author Contributions:** Original project idea: C.D. and N.T.; system design, D.V., A.L., M.G., N.T., C.D., C.R., and M.-È.H.; methodology, A.L., D.V., M.G., N.T., and M.-È.H.; formal analysis, N.T., M.È.H., and D.V.; investigation, C.R, N.T., J.C., L.C., M.È.H, D.V.; writing—original draft preparation, N.T., D.V., and M.È.H.; writing—review and editing, D.V., M.È.H, A.L., C.R., J.C., L.C., M.G., G.B., and C.D.; visualization, N.T.; supervision, M.G., C.D., and G.B.; project administration, M.G., C.D., and G.B.; funding acquisition, C.D. and G.B.

**Funding:** This research was funded by Ministère du Développement Économique, de l'Innovation et des Exportations du Gouvernement du Québec through the "programme de soutien à la recherche volet 2: appui au financement d'infrastructures de recherche" project M-11638 (CD), the Quebec Respiratory Health Network (CD), NSERC discovery gran<sup>t</sup> RGPIN-2014-05900 (CD) and Canadian Institutes of Health Research Foundation gran<sup>t</sup> 148361 (GB).

**Acknowledgments:** We thank Serge Simard for statistical analysis. We also thank Cédric Morin for software conception and Dan Zegan for his input the design of the chamber system. NIOSH two-stage bioaerosols cyclone samplers were kindly provided by William G. Lindsley.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
