Most respirators are constructed using 4 or 5 layers. The fit, filtration, and breathability are what matters, not the layer count. In fact, respirator manufacturers have been migrating to reduced layer count using better materials in order to improve breathability while maintaining >95% filtration. Most respirators use 2 inner layers of nonwoven meltblown fabric for particulate filtration. Sometimes a 3rd layer is added for mechanical stiffness or for extra fluids protection. These inner layers are then encased in 2 layers of spunbond fabric which is very breathable and gives the mask strength and shape. This spunbond doesn't meaningfully provide filtration - it's mainly used for structure.