41.   The Environmental Protection Agency last November issued proposed rules on small dust particles and ozone in the atmosphere.

42.   Theories about the composition of interplanetary dust particles varied wildly.

43.   They create a static charge that attracts dust particles.

44.   This is why a dust particle can wander, seemingly endlessly, through the air, pushed by the smallest of currents.

45.   Tiny radioactive dust particles, carried by the wind and by building ventilation systems, would need to be cleaned from every surface by workers wearing protective gear.

46.   Veverka speculates that perhaps static electricity lifted fine dust particles off the surface, allowing them to move down to the bottom.

47.   Varnish inevitably picks up dust particles.

48.   When water hits most glass it beads up and runs off, and dust particles in rainwater rivulets can leave streaks or spots.

49.   Pneumoconiosis is a fibrous hardening of the lungs caused by inhalation of irritating dust particles.

50.   Dust particles containing beryllium also can become lodged under the skin, causing lesions.