Particle resuspension via human activity

This dissertation consists of three correlated parts that are related to particle resuspension from floorings in indoor environment. The term resuspension in this dissertation refers the re-entrainment of deposited particles into atmosphere via mechanic disturbances by human activity indoors, except where it is specified.;The second part involved 54 resuspension experiments conducted in a room-scale environmental chamber. Three floorings types and two ventilation configurations were tested. Air exchange rate were fixed during the experiments, and the temperature/RH were monitored. The airborne particle concentration was measured by an array of optical particle counters (OPCs) in the chamber. Resuspension rates were estimated in size ranges of 0.8–1, 1.0–2.0, 2.0–5.0, and 5.0–10 μm ranging from 10-5–10 -2 hr-1, with higher resuspension rates associated with larger particles. Resuspension via walking activity varied from experiment to experiment. A "heavy and fast" walking style was associated with a higher resuspension rate than a less active style. Given the same floor loading of the test particles, resuspension rates for the carpeted floor were on the same order of magnitude but significantly higher than those for the hard floor.;In the third part, an image analysis method (IAM) was adapted to characterize the particle distribution on fabric floorings. The IAM results showed the variability of particles loading on various carpets. The dust particles on fibers from ten carpets vary in sizes. The normal dust loading varies from house to house from 3.6×106 particles/cm2 to 8.2×106 particles/cm2. The dust particle number distribution for size less than 10 μm is compared with that obtained from test carpet used in the chamber study. The carpets in the real environment have more particles in the small size ranges: about twice as high as those found in test carpets in the 0.8-5 μm size range. The distribution of particle surface concentration along the particle size on the test carpet is quite different from those distribution estimated from the ATD particles size distribution, which might be due to the different counting methods.;The first part reviews the literature related to particle resuspension. Fundamental concepts and kinetics of resuspension of particles were extracted from previous studies. Suggestions for future research on indoor particle resuspension have been given based on the literature reviews and the findings of part 2 and part 3.