In Industries it is necessary to wear a protective mask, to protect the workers from the materials that are working with. In a woollen mill tiny hairs break off from the wool fibres and these will cause irritation within the lung if they are breathed in. During normal production the fibres are kept moist and they fall to the ground or machine ledges and do not cause any harm. If however these fibres dry out and become dislodged during cleaning they can be very dangerous, this is why it is necessary to wear a mask.
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