Most people in the United States (US) spend considerable amount of time indoors—about 90% of their time as compared to outdoors, which makes the US population vulnerable to adverse health effects of indoor air contaminants. Volatile organic compound (VOC) concentrations are well-known to be higher in indoor air than outdoor air. One source of VOC concentrations in indoor air that has gained considerable attention in public health and environmental regulatory communities is vapor intrusion. Vapor intrusion is the process by which subsurface vapors enter indoor spaces from contaminated soil and groundwater. It has been documented to cause indoor air contamination within hundreds of thousands of communities across the US. Vapor intrusion is well-known to be difficult to characterize because indoor air concentrations exhibit considerable temporal and spatial variability in homes throughout impacted communities. Unexplained variations in field data have not been systematically investigated using theoretical fate and transport processes. This study incorporates the use of numerical models to better understand processes that influence spatial and temporal variability in field data. The overall research hypothesis is that variability in indoor air VOC concentrations can be (partially) explained by variations in building air exchange rate (AER) and pressure differentials between indoor spaces and outdoor spaces. Neither AER nor pressure differentials are currently calculated by existing vapor intrusion numerical models. To date, most vapor intrusion models have focused on subsurface fate and transport processes; however, there is a need to understand the role of aboveground processes in the context of vapor intrusion exposure risks, which are commonly measured as indoor air VOC concentrations. Recent field studies identify these parameters as potentially important and their important role within the broader field of indoor air quality sciences has been well-documented, but more research is needed to investigate these parameters within the specific context of vapor intrusion. To test the overall hypothesis, the dissertation research developed a new vapor intrusion modeling technique that combines subsurface fate and transport modeling with building science approaches for modeling driving forces, such as wind and stack effects. The modeling results are compared with field data measurements from actual vapor intrusion sites and confirms that the research is relevant to not only academic researchers, but also policy decision makers.

En les darreres dècades el nombre d'accidents ocurreguts en la industria química i durant el transport de mercaderies perilloses ha augmentat substancialment, registrant-se en la seva majoria en zones densament poblades. Els núvols de gasos tòxics solen originar-se en aquests accidents i malgrat que són menys probables que altres tipus d'accidents, poden afectar grans extensions i contaminar zones poblades, provocant greus conseqüències. Això comporta un gran repte per a les autoritats civils, que han d'avaluar i decidir l'àrea que cal evacuar i l'àrea en la que s'ha d'implementar el confinament com a mesura de protecció. L'avaluació de l'efectivitat del confinament comprèn tres etapes fonamentals: el càlcul de la dispersió exterior, el càlcul de la concentració interior en funció de la concentració exterior i l'avaluació dels efectes adversos per a la salut. Aquesta tesi s'enfoca principalment en l'estudi de la segona etapa, la qual és funció de la taxa d'infiltració d'aire en les edificacions.Inicialment es va realitzar una extensa revisió bibliogràfica sobre les tres etapes, fent èmfasi en la cerca de models pel càlcul de la concentració interior, la taxa d'infiltració y l'hermeticitat de les vivendes. Posteriorment, a través d'una anàlisi de sensibilitat es trobà que la taxa de renovació d'aire té una gran influencia sobre l'efectivitat del confinament i, a més, atès que aquesta varia per cada edificació, el coneixement de la seva distribució en una població és necessari per a una avaluació adequada de l'efectivitat del confinament, ja que suposar-la constant per a totes les edificacions pot comportar sobreestimacions o subestimacions del radi d'evacuació. Per tant, amb la finalitat d'obtenir una aproximació de la distribució de l'hermeticitat, es va aplicar el model desenvolupat pel Lawrence Berkeley National Laboratory (LBNL), que prové de dades de vivendes nord-americanes, a les vivendes catalanes. De tota manera, els resultats obtinguts es trobaven esbiaixats a les zones climàtiques, essent les prediccions per a vivendes ubicades en zones seques més hermètiques que en zones humides. En el cas de Catalunya, on les tècniques constructives no varien significativament d'una zona a una altra i la majoria de vivendes estan construïdes a base de materials pesats, no és d'esperar una diferència tan marcada com la predita pel model del LBNL. Per tant, es va decidir desenvolupar un model per a les vivendes catalanes utilitzant la base de dades de taxes d'infiltració de vivendes unifamiliars del CETE de Lyon, ja que aquestes vivendes tenen més similitud amb les vivendes catalanes que no pas les nord-americanes.El model desenvolupat, denominat UPC-CETE, permet estimar l'hermeticitat de les vivendes unifamiliars en funció de l'àrea, el número de pisos, l'edat i el tipus d'estructura constructiva: lleugera o pesada. Els valors d'hermeticitat predits amb aquest model foren menors que els obtinguts amb el model del LNBL, tal com s'esperava. Finalment, per tal de validar i millorar el model desenvolupat, es van realitzar mesures de la taxa de renovació d'aire en diverses vivendes de Catalunya i també en habitacions prèviament condicionades per ser utilitzades com a refugi, per tal d'avaluar la reducció guanyada sobre la taxa de renovació de tota la vivenda. Com a mitjana, s'obtingueren reduccions d'un 35% i es trobà que les reduccions més grans tenien lloc en vivendes antigues, amb àrees petites d'una o dues plantes. El model UPC-CETE millorat a partir dels resultats obtinguts en les proves experimentals, s'incorporà a la metodologia per avaluar l'efectivitat del confinament en l'etapa d'estimació de la taxa de renovació d'aire, evitant l'ús d'un valor constant per a totes les vivendes i promovent així l'ús d'una distribució d'aquest paràmetre per secció censal afectada dins la població. / During the last decades the number of accidents in chemical industries and during transportation of hazardous substances has significantly increased, with most of them occurring in highly populated areas. One of the possible accidents is a toxic gas cloud, which although less common than other major hazards could affect larger areas reaching populated zones and producing more severe consequences. This implies then, a great challenge to emergency managers who must plan and decide the areas where protection measures should be implemented: shelter in place and/or evacuation. The assessment of the effectiveness of shelter in place is subjected to three main stages: the calculation of the outdoor gas dispersion, the estimation of indoor concentration from outdoor concentration and the evaluation of human vulnerability. This thesis is mainly focused on the study of the second stage which is primarily a function of buildings leakage.Initially we performed a bibliographic survey with special interest on the models to estimate indoor concentration from outdoor concentration, airtightness of dwellings and ventilation models. Then, through a sensitivity analysis, we found that the air exchange rate has a great influence on the effectiveness of shelter in place. Moreover, since this parameter is different for each building, the knowledge of the distribution of this variable in the affected population would lead to a more accurate assessment of the effectiveness of shelter in place, because if we assume it as a fix value, constant for all buildings, over or underestimations of the evacuation radius may occur. Therefore, with the aim of making an estimation of the airtightness distribution in Catalunya, we applied the model developed by the Lawrence Berkeley National Laboratory (LBNL), a model based on data from North American dwellings, to Catalan dwellings. The results obtained were influenced by climate zones, due to the coefficients of the model, being more airtight the predictions for dwellings located in dry climates than for dwellings in humid zones. In the case of Catalunya, where constructions techniques do not differ significantly from one zone to another and most of the dwellings consist of a heavy structure, a difference such as that predicted by the model of the LBNL is not expected. Consequently, we decided to develop a model for Catalan dwellings using the air leakage database from the CETE de Lyon, since French dwellings are more likely to Catalan dwellings than US dwellings. The model developed, named the UPC-CETE model, predicts the airtightness of single-family dwellings as a function of the floor area, the age, the number of stories and the structure type: light or heavy. The airtihgtness values predicted with this model were smaller than those predicted with the model of the LBNL, as was expected. Finally, in order to validate and improve the model developed we carried out a series of trials to measure the air exchange rate in some Catalan dwellings. Measurements in sealed rooms were also performed with the aim of assessing the reduction gained on the air exchange rate with regards to the air exchange rate of the whole dwelling. On average, we obtained reductions of 35% and found that larger reductions belonged to old dwellings with small floor areas and 1 or 2 stories. The improved model was incorporated on the methodology to assess shelter in place effectiveness on the stage concerning the estimation of the air exchange rate of the dwellings located on the affected zone; therefore, the assumption of a constant value is avoided. These measurements and the model constitute therefore the first proposal for estimating the airtightness distribution of single-family dwellings that could be used by Catalan authorities for emergency response planning.

No description available.

Acute indoor concentrations of benzene and ethanol were evaluated in the California Polytechnic State University San Luis Obispo’s pilot winery workroom. Air samples were collected during four different wine-making activities: fermentation, fermentation with Brix content testing, post-alcoholic fermentation pressing, and storage/finishing. Average workroom benzene concentrations ranged from 0.05 to 0.12 mg/m3. Ethanol concentrations in the winery workroom varied with the activity, ranging from 0.9 to 12 mg/m3. Pressing and fermentation with Brix content testing both led to higher indoor ethanol concentrations than fermentation without Brix content testing and storage/finishing. Tracer gas decay air exchange tests were conducted to determine the air exchange rate of the winery workroom. A single-space mass-balance model was used to estimate the air exchange rate for the entire workroom. The calculated air exchange rates were correlated with wind speeds and wind direction to create a linear model estimating air exchange rates based on wind speed. These air exchange rates and the indoor concentrations of ethanol were used with the single-space mass-balance model to calculate an ethanol emission rate for each activity. Total estimated ethanol emissions for the four activities were 3.1 lbs. ethanol per 1000 gallons of wine produced.

No description available.

This thesis examines the influence of the intensity of pressure strain of structures printed on the value of air permeability. The measurement is carried out using Blower Door Test on six variants using OSB boards as airtightening layers in the building. Part of the research was to verify the suitability of the test chamber and measuring devices for similar purposes and adjustment chamber