Fig 1 -

(a) Disposable procedure mask: Henan Liwei Biological Pharmaceutical Co. Ltd; (b) Multi-layer mask: four layered system comprised of two layers of quilt batting between an outer and inner layer of cotton; (c) Non-woven polypropylene ‘craft’ material (manufactured by smart-fab^®); (d) “N95-like” electret filter membrane material (purchased from Amazon.ca) used as the middle filter layer, as part of a multi-layer mask; (e) 2-Layer mask: quilt batting/cotton mask; (f) KN95 mask: MedSup Canada Protective Face Mask, and; (g) N95 FFR: 3M^™ model 9210.