In the construction industry, dust occurs during many different  activities. Usually this involves mineral mixed dust, e.g. from sand, lime, gypsum, cement or concrete. This mixed dust partly contains quartz fine dust, which has a diameter of less than 1 µm and therefore belongs to the category of A-dusts. These dusts are so small that they reach the alveoli of the lungs and can lead from respiratory diseases to silicosis. A dust particle with an average size of 1 μm takes almost 7 hours to reach the ground again from a height of 1 metre.