Fine Particles 3. Environmental Research Foundation . . P.O. Box 5036, Annapolis, MD 21403 . .
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To subscribe, E-mail the words . . A micrometer is a millionth of a meter and a meter is about 39 inches. Now, just two years later, an extensive medical study has shown that human illness can result from particles in the air at levels that fall within EPA guidelines. In other words, an area may meet the federal requirements and yet still make residents sick. The new standard specifically recognizes that particles smaller than 10 micrometers in diameter are not filtered out by the nose and throat and can pass into the large airways below the trachea.