AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Physical Characterization of Indoor Dust
Haaland Daniel, Alireza Mahdavi, JEFFREY SIEGEL, University of Toronto
Abstract Number: 280 Working Group: Indoor Aerosols
Abstract Indoor particle characterization tends to focus on short-term measurements of airborne particulate matter. A complete picture of exposure requires a longer-term assessment of particles. Such investigations are traditionally done with samples of settled dust and occasionally with the dust that collects on filters in central HVAC systems. Physical characterization of dust samples is typically completed with sieving or microscopy techniques, which provide the most information on the largest particles (>10 µm) in the sample. This presentation describes an alternate approach where a laser diffraction particle sizer is used with a liquid extract of dust to size particles from dust extracted from a filter. First test dusts with known size distributions were used to generate optical properties for indoor dusts. Next, test dusts were artificially loaded on to filters and extracted using chemical (surfactant addition) and physical (sonication) means to test and optimize dust extraction protocols. The optimized method is then used for two applications to demonstrate the utility and the uncertainties associated with the test method. The first application is assessing the particle size of particles collected on the filters of 10 portable air cleaners deployed for one week in different residential settings. These dust samples are compared to contemporaneous airborne particle measurements to elucidate differences between airborne and dust-based measurement approaches. The second application is used to validate in-situ filter efficiency measurements by comparing upstream downstream concentration measurements to the actual size distribution and mass removed to the filter. The results in general suggest that the approach has several applications to the investigation of indoor particles. The largest uncertainties arise from the agglomeration of dust particles, the variations in optical properties between dusts collected in different environments, and the very wide range of particle sizes present in typical dusts.