| Descript |
123 p |
| Note |
Source: Dissertation Abstracts International, Volume: 67-09, Section: B, page: 5318 |
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Adviser: Lynn M. Hildemann |
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Thesis (Ph.D.)--Stanford University, 2006 |
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This study determines the fraction of indoor PM originating from outdoor sources using an air-exchange mass balance model and a chemical mass balance model. We measured indoor and outdoor particle concentrations using gravimetric filter samplers, laser particle counters, and nephelometers, and characterized the infiltration rate using sulfur hexafluoride as a tracer gas in a single-family home in Redwood City, California. The filter samples provided mass concentration data and samples for chemical analysis. We quantified the concentration of thirteen elements found in the PM using microwave acid extraction and inductively-coupled plasma mass spectrometry. From our mass balance models, we found that during vigorous cleaning or other indoor activities nearly all of the PM5 and most of the PM2.5 originated from indoor sources. Even when vigorous activity was absent, one quarter to one half of the PM2.5 and half of the PM5 originated from indoor sources |
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We encountered systematic errors in the performance of the laser particle counters and the nephelometers when compared with the gravimetric methods. Estimates of the PM mass concentration calculated from the laser particle counter results systematically underpredicted the concentrations measured by the gravimetric reference method. In addition, the nephelometers showed a systematic bias in the measurement of scattering efficiency for indoor PM compared to outdoor PM. Our study then proposed several model aerosols with realistic index of refraction and particle density values. From Mie theory, we calculated the light-scattering properties of the model aerosols. We used the resulting scattering functions, along with the optical properties of the instruments, to simulate the measurement response to each of the model aerosols and to recalibrate the laser particle counter size results. Our recalibration improved the accuracy of the laser particle counter mass estimate, nearly doubling the fraction of the measured mass explained by the optical estimate. Finally, we used the model aerosol optical properties and the corrected particle size data to simulate the response of the nephelometer to each model aerosol. By comparing these results to the field measurements, the simulated nephelometer response provides a novel method of evaluating the apparent index of refraction of the real aerosol |
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School code: 0212 |
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DDC |
| Host Item |
Dissertation Abstracts International 67-09B
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| Subject |
Engineering, Civil
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Engineering, Environmental
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0543
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0775
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| Alt Author |
Stanford University
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