A real-world study was undertaken of the indoor air quality in a recently-built single family home in central Sweden, to establish whether demand controlled ventilation provided superior interior conditions, when compared with other air supply strategies, including the standard used by the Swedish buildings regulator. The property was highly airtight, with ventilation achieved using a forced exhaust system. Extraction was possible from all rooms of the house, and using a Renson Healthbox air handling unit, the rates of air flow from each room could be adjusted either according to a time schedule, or under demand control according to the unit’s sensing of the air quality in individual rooms. Five ventilation modes were evaluated, each for a period of 24 hours. Occupancy of the house was standardised, with test participants. Two separate air quality monitors were deployed to verify whether measurements made at the air handling unit were representative of the conditions that occupants experienced. Key measurements were the stable level of carbon dioxide overnight in an occupied double bedroom and the time taken for that room to refresh to background CO2 level the following day. The time taken for a kitchen/living room to similarly refresh was also examined. The study found that demand controlled ventilation achieved indoor air quality – assessed on carbon dioxide concentration – comparable with rates of fixed ventilation far greater than the regulated standard. In doing so, the air volume exchanged over a representative day was 33 % less than that standard, providing for significant energy savings. The parallel monitoring of air quality inside the room and via the air exhaust duct showed noticeable variation, but indicated the air handling unit under demand control would never ventilate insufficiently, based on its internal CO2 sensors.

Les éléments trace métalliques (ETM) sont des polluants qui sont sources de préoccupations majeures à cause de leurs toxicités et de leurs propriétés cumulatives. Certains d’eux peuvent être cancérogènes. La métropole de Sfax, située au sud de la Tunisie, a été touchée par des rejets et émissions d’ETM depuis des décennies. Plusieurs études ont confirmé que la pollution métallique est principalement d’origine anthropique, liée en particulier aux activités industrielles. Cela présente un risque sur la santé des habitants, particulièrement pour ceux qui sont également exposés par leur métier dans des procédés industriels. L’objectif de cette étude est d’évaluer les risques sanitaires associés à l’exposition professionnelle dans les industries qui manipulent des ETM dans leurs processus de production, en suivant l’approche de l’évaluation des risques sanitaires. Dans ce but, cinq entreprises qui utilisent des métaux comme matière première pour produire une variété de produits métalliques, ont accepté d’adhérer à notre étude. Les métaux qui étaient explorés sont Al, Cr, Ni, Cu, Zn and Pb. Des modèles mathématiques de prédiction des expositions professionnelles aux agents chimiques ont été utilisés pour estimer les concentrations des ETM dans l’air intérieur pour 15 postes différents. Des prélèvements atmosphériques ont été effectués afin de comparer les concentrations prédites à celles mesurées, en utilisant des prélèvements individuels ou sur postes fixes. Finalement, des prélèvements urinaires ont été collectés chez 61 travailleurs afin d’évaluer le lien entre l’excrétion des ETM et les niveaux atmosphériques. Globalement, les estimations des concentrations atmosphériques avaient une bonne concordance avec les valeurs mesurées sur l’ensemble des postes de travail. Des meilleures prédictions ont été trouvées pour certaines activités, en particulier pour des processus de découpage des tôles et de soudures. Les valeurs qui correspondent au 90ème percentile de la distribution de l’exposition ont été utilisées pour le calcul du « interaction-based hazard index HIint » pour évaluer les risques associés aux mélanges d’ETM. Un excès de risque total de cancer a été aussi calculé. Les résultats ont montré des expositions élevées qui peuvent provoquer des pathologies respiratoires, avec un HIint allant jusqu’à 93,6. Les niveaux les plus élevés sont attribués à la soudure à l'arc à l'électrode enrobée et au débitage et cisaillage des tôles. Ces risques augmentent à cause de l’effet synergique qui existe entre Cr, Ni et Cu. Des risques élevés de cancer du poumon et du rein ont été encore démontrés (risque total vie entière de cancer pour les ouvriers exposés : 3.7×10-4). Ce travail montre que les modèles mathématiques peuvent prédire correctement les niveaux d’exposition des ETM dans l’air intérieur pour plusieurs processus de la métallurgie. Ce résultat est intéressant pour aider les différents acteurs pour piloter de manière efficiente les systèmes de surveillance et la réduction des expositions dans ce secteur économique. Des progrès en matière d’hygiène industrielle sont nécessaires dans ce secteur industriel pour minimiser le risque sanitaire élevé auquel sont actuellement exposés les travailleurs concernés / Trace metallic elements (TMEs) are pollutants of great concern even in trace amounts because of their toxicity and cumulative property. Some of them can be carcinogenic. The Sfax metropolis, located in the southern region of Tunisia, has been affected by releases of TMEs for decades. Several studies confirmed that this pollution is predominantly originated from anthropogenic sources, mainly from industrial activities. It represents a threat to the health of residents, particularly for those also exposed during occupational activities in industrial processes. The present study aims to assess health risks associated with occupational exposure in industries handling TMEs in their production processes, following the human health risk assessment approach. To this end, five companies using raw material containing TMEs to produce a variety of metallic products accepted to participate to the study. The metals that were investigated are Al, Cr, Ni, Cu, Zn and Pb. Mathematical models for estimating occupational exposure to chemicals were used to predict indoor air TME exposure levels in 15 different job tasks. Air monitoring was conducted in order to compare the predicted workplace air concentrations versus the direct measured ones, using both workplace-fixed monitors and personal samplers. And finally, urine samples were collected from 61 workers to assess whether TMEs excretion correlate with job exposure levels. Globally, the predicted air estimates relate well with measured concentrations over the whole set of job tasks. Better predictions were found for certain activities, in particular for steel cutting and welding processes. The values that correspond to the 90th percentile of the exposure distribution were then used in the interaction-based hazard index HIint to assess health risks associated with the mixtures of TMEs. Total cancer risk was also investigated. Results showed high exposures for metals that may elicit respiratory conditions, with a HIint reaching 93.6, the highest levels being for the shielded metal arc welding and metal shearing and slitting tasks. The risk is enhanced by a synergetic effect between Cr, Ni and Cu. High risks of lung and kidney cancers were demonstrated (the predicted life-long total cancer risk for exposed workers is 3.7×10-4). This work shows that mathematical models can be accurate in predicting TME airborne exposure levels for several processes in the metallurgic industry, a result that is of interest to help the different stakeholders to monitor efficiently exposure surveillance and abatement. Progress in industrial hygiene is needed in this industrial sector to reduce the high level of health risks currently experienced by the metalworking workers

This thesis pertains to two R&D objectives associated with deploying TMFD sensor technology for meeting AARST-NRPP metrics for Radon (Rn) in-air detection, as well as for monitoring of ultra-trace actinides in air, amidst other Rn-progeny alpha emitting radionuclides. A challenge has persisted over the past 40+ years for detecting trace actinides in air amidst a 100-1000x higher Rn-progeny background. This thesis had a primary aim for addressing this challenge, and developing and assessing for a novel technology solution. Both objectives were successfully met. Methods, designs, and experimental effects of apparatus are discussed for successful Rn and progeny detection for 1-100 pCi/L concentration levels, as well as for Rn-progeny “blind” spectroscopic detection of 10-12 μCi/cc concentrations of actinides (Pu/U/Am) in air. The resulting CTMFD based technology was compared with the state-of-art “Alpha Sentry” CAM system and found to offer superior performance in multiple categories, and ~18x improvement in time to detect (e.g. at 0.02 DAC in 3 hrs vs ~70 hrs for state-of-art) for actinides while also remaining ~100% blind to ~102x higher Rn-progeny background; and, with 1 keV energy resolution vs ~300-400 keV for Alpha Sentry.