“Characterizing Household Dirt: 1928-2001″

2001:59: Millette, Few

Proc. of the Second NSF International Conf. on Indoor Air Health. Jan. 29-31, Miami Beach, FL. pp 174-183


Household dirt can be characterized by a number of parameters including particle size, particle type, and organic verses inorganic fractions. Early work by the Hoover Company used sieving, ashing and microscopy to characterize a number of darts collected from residences in 56 cities. They found that household darts varied considerably but that there were a number of general similarities. The average organic (combustible) component was approximately 40% of the vacuumed dirt versus 60% for the inorganic material.

The average particle size distribution information suggested that approximately 65% of the particles did not pass through a 300 um mesh sieve, approximately 30% of the remaining particles did not pass through a 75 um mesh sieve and approximately 5% of the residue was finer than 75 um. Microscopical and chemical analyses showed that the combustible constituents included: animal fibers (hair, wool), cellulosic fibers (cotton, paper, wood), gums and resins, fats, oils and rubber particles. The inorganic (noncombustible) material was composed primarily of soil minerals (quartz, feldspar) and particles of soil or building materials (gypsum, limestone, dolomite).

Reports in 1961 (University of Nebraska) and 1975 (Hoover’s North Canton Study) found similar average percentages of combustible material in household dirt as well as similar particle size distributions. Current analyses in IAQ  studies involving residential and office darts suggest that most darts can be characterized by light microscopical methods augmented when necessary with electron microscopy, infrared spectroscopy and gas chromatography using about 20 general constituent categories. These categories include those identified during the early Hoover work with additional particle types related to current product materials such as, glass fibers, synthetic fibers, and copy toner.

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