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MODELING INDOOR EXPOSURES TO OUTDOOR PARTICULATE MATTER ACROSS THE U.S. RESIDENTIAL BUILDING STOCK
Title
MODELING INDOOR EXPOSURES TO OUTDOOR PARTICULATE MATTER ACROSS THE U.S. RESIDENTIAL BUILDING STOCK
Creator
Elorch, Zeineb
Date
2013, 2013-07
Description
Elevated ambient concentrations of fine and ultrafine particulate matter are consistently linked with adverse health effects in...
Show moreElevated ambient concentrations of fine and ultrafine particulate matter are consistently linked with adverse health effects in epidemiological studies. However, because people spend most of their time indoors (particularly at home) and outdoor particles can infiltrate into buildings with varying efficiencies, much of human inhalation exposure to outdoor particles actually occurs inside residences. Consequently, relying on ambient measurements of particulate matter can result in a significant exposure misclassification in epidemiological studies. To address the range of this misclassification in U.S. residences, this work predicts the statistical distribution of long-term average size-resolved indoor proportions of outdoor particles (from 0.001 to 10 μm) across the entire U.S. single-family residential building stock by means of Monte Carlo simulations. Best available data was used for distributions of important building-related model inputs (e.g., air exchange rates, penetration factors, deposition rates, and others). Overall, results suggest that infiltration factors (i.e., the indoor-outdoor particle concentration ratio in the absence of indoor sources) vary highly among residences across the U.S. residential building stock. Long-term average size-resolved infiltration factors are estimated to vary by a factor of 20-100+ from the least protective of single-family homes in the U.S. (99th percentile) to the most protective (1st percentile), depending on particle size. Long-term average infiltration factors are predicted to be within a factor of 2-4 in the majority of homes (between the 25th and 75th percentiles of homes). A regression analysis further shows that parameters such as deposition rates, air exchange rates, penetration factors, and filter removal efficiencies are the most influential parameters for predicting infiltration factors. xiii Finally, the predicted distributions of size-resolved infiltration factors were used to map to archetypal outdoor particle size distributions to estimate absolute concentrations and ultimately inhalation doses of both ultrafine particles (UFPs) and PM2.5 in an adult male. Inhalation doses of UFPs and PM2.5 were estimated to be 43-49 and 21-22 times higher, respectively, in the least protective homes (99th percentile) versus the most protective homes (1st percentile). Taken together, these results suggest that a wide variability in size-resolved infiltration factors among U.S. residences leads to large variations in the dose of particles inhaled in indoor environments, which should be accounted for in future epidemiological studies.
M.S. in Civil Engineering, July 2013
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