Illustration ST 14 shows three examples of dust samples.
These were collected respectively (from left to right) in an office, on the street and in a bedroom. These microscopic images (magnification factor 65x or 125x) show that dust is a heterogeneous mixture of particles of various types.

In areas where much textile is present, such as the office or the bedroom, chiefly dust fibrous particles are present. Dust from the street on the other hand contains more heterogeneous, granular particles.