The masks and dummy used are shown in Figure 2. The three-layer mask in Figure 2B has two outer layers each 0.4-mm thick made of 80% polyester 20% elastane with the internal filter layer being 1.0 mm 100% polypropylene. The filter covers the area of the mouth and nose but around chin, cheeks and nose bridge the fabric is just a single layer. Compliance with the testing methods of the CWA 17553 was claimed by the supplier but packaging was not marked accordingly.