PARTICLES of 10 μm or less, with which dean room operators are particularly concerned, are mainly invisible to the naked eye, are of differing shapes and derive from a wide range of sources. They range from human hairs 50-150 μm, dust 1-100 μm, bacteria 0.5-10 μm. Generally particles greater than 40 μm can be seen by the human eye. People are a major source of contamination through body regenerative processes (skin flakes, oils, hair), behaviour (rate of movement, sneezing, coughing) and attitude (work habits, communication). Personnel activity rapidly accelerates the rate of generation of particles.
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