21.   It also lay at the heart of quantum physics, or the study of very small particles.

22.   It is believed that the small particles may be more dangerous because people can breathe them deeply into the lungs, where lung tissue can be damaged.

23.   Lashes guard against small particles and dust in the air that can get in the eye and cause problems.

24.   Little is known about the consequences of exposure to very small particles of soot because they are typically present in high concentrations only when other pollutants are also plentiful.

25.   Low-level haze emerges when small particles of pollution and natural matter get baked by the sun.

26.   Oil can be re-used at a later date if it is filtered of any small particles and if the smell remains fresh.

27.   Officials at the Appalachian Mountain Club, which monitors extremely small particles in New Hampshire, said fine soot and dust pollution is a pervasive problem.

28.   Of particular concern are small particles that are too small to be detected by radar or ground-based tracking systems.

29.   Platelets are small particles in the blood that bind together to prevent bleeding.

30.   Quantum mechanics is a system of probabalistic rules governing the discontinuos jumps in behavior of very small particles of matter and energy.