Asthma is a common chronic disorder in Western countries and is increasing in prevalence in both children and adults. Although genetic risk for atopy is an important factor for the development of asthma, it does not explain the tremendous increase in prevalence seen in recent decades. Environmental exposures in early life that affect immune maturation appear to be the key factors for the development of asthma. The indoor environment is a likely candidate since infants spend 90% of the time indoors at a time when immune deviation usually occurs. Exposure to indoor pollutants represents a potentially modifiable cause of allergic sensitization and asthma. In this context, it becomes important to establish which environmental factors might influence the development of asthma in predisposed individuals. Allergic reactions to certain environmental allergens such as house dust mites, cats, and cockroaches, have shown a high level of association with asthma prevalence, but in the last five years increasing attention is being paid to indoor environmental factors, other than allergens, that may be involved in the development of this disorder. The potential irritants include nitrogen dioxide, environmental tobacco smoke, formaldehyde, volatile organic compounds, and particulate matter (PM[subscript]2.5;10).The aim of the study was to examine the nature of the relationship between asthma and environmental exposure to indoor environmental irritants.A population based case-control study had been carried out in Perth, Western Australia. The study population consisted of young children (N = 192) aged between 6 months and 3 years old. Cases (n = 88) were asthmatic children who attended the Accident and Emergency Department at Princess Margaret Hospital for Children and were discharged with asthma as a primary diagnosis. Controls (n = 104) were children in the same age group as cases ++ / who had never been diagnosed with asthma, identified from birth records accessed through the Health Department of Western Australia. Information, regarding the respiratory conditions experienced by the study children and characteristics of the home, was collected using a standardised questionnaire. The questionnaire consists of questions about potential risk factors for asthma and these factors were grouped in three categories. The first category included information on personal and social factors such as age and gender of the child, and mother's and father's educational level. The second category was related to personal susceptibility factors such as child's allergy, parental and sibling's asthma, eczema and hay fever. The last category included environmental exposure in the house such as parental and visitors smoking inside the house, exposure to gas heating and cooking, kerosene space heaters, open fireplaces, and pets. Other questions related to environmental exposure were the presence of air conditioning, humidifiers, and type of floor covering in the child's bedroom and the living room. Measurements of indoor nitrogen dioxide (NO[subscript]2), formaldehyde (HCHO), volatile organic compounds (VOCs), particulate matter (PM[subscript]10), and house dust mite exposure were made on two occasions over one year, winter (middle June through September 1998) and summer (December 1998 through March 1999), Indoor temperature and relative humidity were also measured. The atopic status of the children was assessed by skin prick tests to common allergens.The study results indicated that age, gender, family history of asthma, atopy and domestic exposure to indoor environmental factors were significant predictors of asthma early in life. The study found that indoor exposure to formaldehyde, volatile organic compounds and house dust mite significantly increased the risk of ++ / having asthma. Presence of air conditioning appeared to be a protective factor for asthma.In conclusion, the study results confirmed the role of susceptibility factors in asthma and show that indoor environmental factors contribute as risk factors for asthma in early stage of fife. The observation that exposure to indoor air pollutants in early childhood is associated with asthma suggests the possibility that irritants in indoor air might be involved in the initiation phase of asthma. Since the quality of the indoor environment is potentially modifiable there might be opportunities for intervention to reduce asthma symptoms. In order to counteract the increasing prevalence in asthma, the significance of the indoor environment where children grow and spend most of their time need to be given greater attention.

<p>Indoor navigation could be used in many applications to enhance performance in</p><p>its specific area. Anything from serious life critical tasks like aiding firefighters or</p><p>coordinating military attacks to more simple every day use like finding a desired</p><p>shop in a large supermarket could be considered. Smartphones of today introduce</p><p>an interesting platform with capabilities like existing, more clumsy, indoor</p><p>navigation systems. The iPhone 3GS is a powerful smartphone that lets the programmer</p><p>use its hardware in an efficient and easy way. The iPhone 3GS has a</p><p>3-axis accelerometer, a 3-axis magnetometer and hardware accelerated image rendering</p><p>which is used in this thesis to track the user on an indoor map. A particle</p><p>filter is used to track the position of the user. The implementation shows how</p><p>many particles the iPhone will be able to handle and update in real time without</p><p>lag in the application.</p>

Thesis (Ph. D.)--University of Texas Health Science Center at Houston, 2005. / Includes bibliographical references (leaves 376-393). Also available online via the Texas Medical Center website (http://digitalcommons.library.tmc.edu/).

Over the last 20 years, navigation has almost become synonymous with satellite positioning, e.g. the Global Positioning System (GPS). On land, sea or in the air, on the road or in a city, knowing ones position is a question of getting a clear line of sight to enough satellites. Unfortunately, since the signals are extremely weak there are environments the GPS signals cannot reach but where positioning is still highly sought after, such as indoors and underwater. Also, because the signals are so weak, GPS is vulnerable to jamming. This thesis is about alternative means of positioning for three scenarios where gps cannot be used. Indoors, there is a desire to accurately position first responders, police officers and soldiers. This could make their work both safer and more efficient. In this thesis an inertial navigation system using a foot mounted inertial magnetic mea- surement unit is studied. For such systems, zero velocity updates can be used to significantly reduce the drift in distance travelled. Unfortunately, the estimated direction one is moving in is also subject to drift, causing large positioning errors. We have therefore chosen to throughly study the key problem of robustly estimating heading indoors. To measure heading, magnetic field measurements can be used as a compass. Unfortunately, they are often disturbed indoors making them unreliable. For estimation support, the turn rate of the sensor can be measured by a gyro but such sensors often have bias problems. In this work, we present two different approaches to estimate heading despite these shortcomings. Our first system uses a Kalman filter bank that recursively estimates if the magnetic readings are disturbed or undisturbed. Our second approach estimates the entire history of headings at once, by matching integrated gyro measurements to a vector of magnetic heading measurements. Large scale experiments are used to evaluate both methods. When the heading estimation is incorporated into our positioning system, experiments show that positioning errors are reduced significantly. We also present a probabilistic stand still detection framework based on accelerometer and gyro measurements. The second and third problems studied are both maritime. Naval navigation systems are today heavily dependent on GPS. Since GPS is easily jammed, the vessels are vulnerable in critical situations. In this work we describe a radar based backup positioning system to be used in case of GPS failure. radar scans are matched using visual features to detect how the surroundings have changed, thereby describing how the vessel has moved. Finally, we study the problem of underwater positioning, an environment gps signals cannot reach. A sensor network can track vessels using acoustics and the magnetic disturbances they induce. But in order to do so, the sensors themselves first have to be accurately positioned. We present a system that positions the sensors using a friendly vessel with a known magnetic signature and trajectory. Simulations show that by studying the magnetic disturbances that the vessel produces, the location of each sensor can be accurately estimated.

Cultural heritage and human comfort: The issue of indoor climate in historic buildings in the twentieth centuryI

The report treats the development and evaluation of a three dimensional user distribution model for a real network simulator. The simulator is used to create realistic predictions of real networks with the use of high resolution maps including a building data base and network data and also an advanced radio model for LTE. Previously all simulations have been performed with a two dimensional user distribution, i.e. all users situated on the ground level. Since it is considered plausible that many LTE users will be indoors in buildings with multiple floors, several three dimensional user distribution models with users not only on the ground floor but also on the higher floors has been developed and implemented in the simulator. The models all account for the change in path loss and SINR to be expected and have been compared in computational time and credibility. The simulations show that by the use of such a three dimensional model there is a significant improvement at low loads but at high loads the interference becomes dominant and the results show a deterioration and approaches the results of the ordinary two dimensional model. The seventh and last model to be investigated shows a desirable computational speed that still does not compromise too much with the accuracy and detailing of the model and is therefore recommended for normal use.

Indoor navigation could be used in many applications to enhance performance in its specific area. Anything from serious life critical tasks like aiding firefighters or coordinating military attacks to more simple every day use like finding a desired shop in a large supermarket could be considered. Smartphones of today introduce an interesting platform with capabilities like existing, more clumsy, indoor navigation systems. The iPhone 3GS is a powerful smartphone that lets the programmer use its hardware in an efficient and easy way. The iPhone 3GS has a 3-axis accelerometer, a 3-axis magnetometer and hardware accelerated image rendering which is used in this thesis to track the user on an indoor map. A particle filter is used to track the position of the user. The implementation shows how many particles the iPhone will be able to handle and update in real time without lag in the application.

Many chemicals off-gas or leech into indoor environments from sources such as consumer products, furnishings, and building materials. An understanding of the pathways from the sources to human exposure is vital in order to implement control strategies and lower exposure. Objects containing Brominated flame retardants (BFRs), one class of semivolatile organic compounds (SVOCs), burn more slowly during combustion. BFRs, especially polybrominated diphenyl ethers (PBDEs), are used in electronic devices including casings and circuit boards. Heat from internal circuitry increases the BFR vapor pressure and the partition coefficient, enhancing its transport out of the substrate and into the indoor environment. In this work, a computer tower in an office setting provides a case study to examine the emissions of, and exposure to, PBDEs. the case of a computer tower, the cooling fan increases the mass transfer coefficient, further increasing emissions. During computer use, the emission rate of PBDEs from the interior of the case is more than double the emission rate from the exterior of the case due to elevated internal temperatures and higher mass transfer due to the cooling fan. The concentration of PBDEs in the room air increases 40 - 80% for every 5°C increase inside the computer case, depending on the PBDE congener. Such enhanced emissions are a concern since recent studies have shown adverse health effects of PBDEs on human health. The major contributions of this work are: A model was developed that is useful for SVOC emissions for various heat and mass transfer situations, including diffusion through the slab and convective boundary conditions on each side of the slab, which may be simplified if the situation warrants; A systematic propagation of the uncertainties and variability of the model parameters was accomplished by using a Monte Carlo method for the input of the parameters into the model; A polydisperse indoor particle distribution was used as a sink, identifying the size-discretized particle phase PBDE concentration; An exposure assessment showed that the inhalation pathway for PBDEs in the gas and particulate phases is relevant and that the particulate phase exposure is dominant. / text

Ozone (O₃) and oxides of nitrogen (NO[subscript x]) are ubiquitous pollutants in many urban areas around the world. Though they mostly originate outdoors, human inhalation exposure to these pollutants largely occurs indoors, because of the large fraction of our time spent inside buildings. Exposure to O₃ and nitrogen dioxide (NO₂) has been associated with decreased respiratory function, onset of asthma, and cardiovascular events. Through laboratory testing, field exposure and modeling, this study evaluates the feasibility and long-term efficiency of using passive removal materials (PRMs) both indoors and outdoors for removal of O₃ and NO[subscript x]. Three photocatalytic coatings used outdoors and four indoor building materials were tested for their capacity to remove NO[subscript x] and O₃. Since materials outdoors experience a wider range of environmental conditions than indoors, their effects on NO[subscript x] removal by photocatalytic coatings were evaluated through full factorial experiments representative of summertime outdoor conditions in Southeast Texas. Photocatalytic coatings were also exposed to real outdoor environments for a year to assess their long-term viability. Indoor materials were exposed to real indoor environments for a six-month period and tested monthly for their capacity to remove O₃. Carbonyl emissions from these materials before and after exposure to O₃ were also tested at regular intervals during the six-month period. Finally, removal capacity of NO and NO₂ by new indoor building materials was tested as well. For outdoor PRMs, results suggest that the effect of certain environmental parameters (contact time, relative humidity, temperature) on NO[subscript x] removal effectiveness are consistent across different photocatalytic coatings, while other effects are coating specific. The type of semiconductor used and resistance to wear of the coating are important factors in its ability to retain removal efficacy over time. For indoor PRMs, two of the four materials tested, an activated carbon mat and perlite-based ceiling tiles, exhibited consistent O₃ removal effectiveness over time with low carbonyl emissions, both before and after ozonation. All materials except for activated carbon mat had higher post-ozonation than pre-ozonation emissions. Post-ozonation emissions were dominated by nonanal. Simulation of the use of indoor and outdoor PRMs on a model building through multi-zone/CFD modeling showed that indoor PRMs alone could lead to concentration reductions up to 18 % for O₃ and 23 % for NO₂ in rooms of the model building selected. Addition of PRMs on the outside of the building led to small reductions in pollutant concentrations in the air infiltrating into the building, leading to negligible changes in indoor concentrations. / text

Microorganisms found in the indoor environment of retail stores are not well studied, despite potentially serious human exposure implications. In this study, filters from central heating, ventilation, and air-conditioning (HVAC) units were used to collect a time-integrated sample of the airborne indoor microbiome in 14 U.S. retail stores. The microbial communities recovered from the filter dust samples were analyzed with pyrosequencing to characterize the fungal and bacterial microbiome present. The objectives of this work were to: (1) characterize the microbial communities present in retail stores, (2) delineate relationships between the indoor microbiome and building or environmental parameters, and (3) evaluate the use of HVAC filter dust as a sample location for indoor microbial investigations. The microbiome in retail stores was observed to be diverse with 4,771 and 1,577 unique operational taxonomic units for bacteria and fungi, respectively. The diverse microbial community detected over time in the same store could not be fully explained by seasonal trends. That indicates that even when utilizing a long-term sampling approach like HVAC filter samples, the indoor microbiome cannot be completely characterized by a single sampling event. The bacterial community in retail stores was influenced by the outdoor microbiome and microbiota commonly associated with human skin. Physical location of the retail stores had some influence on the bacterial microbial community present and strongly impacted the fungal community recovered. Air exchange rate did not influence the observed bacterial or fungal communities. In a comparison to five other indoor air samplers, passive samplers including HVAC filter dust and settled dust captured a higher diversity of the microbial community. The collection of a more diverse sample may allow detection of potentially pathogenic microorganisms. However, there was significant difference in the microbial community structures recovered between samplers in the same sampling event which suggests sampling methodology has an impact on the inferred microbiome recovered. The overall results from this study indicate that retail stores harbor a diverse microbial community that varies over time. / text