Coloured scanning electron micrograph (SEM) of pollen grains on material from the inner layers of a face mask. The inner layers are made from a meltblown fabric, a fine nonwoven fabric formed from fibres of thermoplastic resin, typically polypropylene, bonded by heat and or pressure. The more inner layers a face mask has, the more effective it is at filtering out particles. Magnification: x200 when printed at 15cm wide.