Acrylic fiber. Long-term exposure to acrylic wool dust is harmful to respiratory system, which may lead to general discomfort and even pneumoconiosis. Dust acts on the respiratory mucosa, causing local hyperfunction, telangiectasia and secretion of a large amount of mucus in the early stage. This is a protective reaction, which forms hypertrophic changes over time, and finally shrinks due to insufficient nutrient supply of mucus cells, forming atrophic changes.