2,4,6-Trinitrotoluene, TNT, is an explosive used in munitions production that is known to cause both aplastic and hemolytic anemia in exposed workers. Deaths have been reported secondary to both varieties of anemia. Studies have shown that TNT systemic absorption is significant by both the respiratory and dermal routes. A literature review revealed that the most recent review article on TNT exposure arguing for a TWA drop from the PEL to the TLV was in 1977 -- this article cited anemia issues in addition to other untoward effects of TNT. No studies encountered looked at hemoglobin change or anemia cases in respiratory protected workers, this present effort may be the first. TNT PEL (1.5mg/m^3), REL (0.5mg/m^3), and TLV (0.1 mg/m^3) 8 hr TWAs all with skin notations (based on animal models and TNT urine metabolite extrapolation in TNT workers suggesting important role of skin absorption). The earliest effects of systemic TNT poisoning involve hgb and hematocrit drop. The investigator hypothesized that respiratory protection alone is insufficient to protect TNT workers from the risk of anemia development and hemoglobin concentration drop. A retrospective observational study design was incorporated utilizing a records review of TNT vapor air concentration values and worker Hgb values for 8 sets of workers in respiratory protection at a demilitarization operation from October 2006 to April 2007 in order to observe whether or not respiratory protection provided adequate protection against anemia development and hemoglobin change; and to help characterize the probable role of TNT skin absorption on hemoglobin change and anemia risk. Worker baseline hgbs were compared with their exposure hgbs for statistically significant hgb concentration changes (two-tailed paired t-tests), and anemia cases were recorded. Mean hgb changes within each of the 8 groups of workers were then regressed on mean TNT air concentrations (10 hr TWAs) using air sampling levels that were performed closest in time to exposure hgbs. Statistically significant hgb concentration drops and anemia cases were apparent at values about the REL and PEL in respiratory protected workers. There were no anemia cases or statistically significant hgb drops at values about the TLV, however. For mean TNT air concentrations from 0.12/m 3 to 0.31/m 3 there was strong positive linear association with regard to magnitude of hgb change (r=0.996). The results appear to confirm the necessity of the skin notation for TNT. However, the TLV seems to be protective against the possibility of anemia risk principally by the dermal route in workers who are respiratory protected. A question does still remain, however, as to anemia risk in workers who are below the TLV who may not be using respiratory protection. The absence of a continued linear association between mean TNT air concentrations and mean hgb change above the 0.31 mg/m 3 TNT level most likely reflects a marrow response, as the TNT levels evident in the study are reported to be mainly associated with extravascular hemolysis with a minimal, or non-existent, aplastic component assumed. This study adds evidence to the argument that the TLV should be adopted as the new PEL.

Detta examensarbete presenterar resultatet från en experimentell studie med syfte att undersöka sambandet mellan ventilation i kontor och smittspridning av luftburna virus och bakterier. Fokuset i studien har framför allt riktats mot coronaviruset och även avgränsats till att enbart studera omblandande-, och deplacerande ventilation under den experimentella delen. Studien genomfördes i ett testrum lokaliserat vid Högskolan i Gävle. Syftet för studien har varit att besvara hur exponeringen av luftburna smittämnen förändras i andningszonen när distributionen av tilluften ändras och om placering av smittkällan i sig har någon betydelse. Studien har även haft för avsikt att besvara vilken utav deplacerande eller omblandande ventilation som lämpar sig bäst vad gäller minimering av överföringssannolikheten från en smittad persons andning. För att besvara studiens frågeställningar genomfördes spårgasmätningar och parallellt med spårgasmätningarna granskades även lufthastigheter och temperaturer på flera positioner i rummet. För omblandande ventilation undersöktes två olika riktningar på tilluftsstrålen, som valdes till vertikal och horisontell. För deplacerande ventilation undersöktes två olika inblåsningstemperaturer vilka var 21,3 ˚C och 16 ˚C. Resultatet av studiens experimentella del visade att deplacerande ventilation hade en mindre överföringssannolikhet vid jämförelse med omblandande ventilation. Detta då överföringssanolikheten låg på 0,3–0,5 % för omblandande och 0,1–0,3 % för deplacerande, vilket visar att deplacerande ventilation generellt varit på en lägre nivå oavsett position av smittkällan. Att deplacerande ventilation har en mindre benägenhet att sprida infektioner vidare bland olika individer i samma rum bekräftas också av flera tidigare artiklar som studerat ämnet. Då omblandande ventilation undersöktes visade studiens experimentella del att resultatet vad gäller riktningen på tilluftstrålen hade en inverkan på överföringssannolikheten. Den vertikala tilluftstrålen påverkade forceringen mellan de termiska dockor som placerades framför varandra, vilket resulterade i en minskning på överföringssannolikheten mitt emot de två olika positionerna där de infekterade dockorna satt. För bägge ventilationssystemen - förutom vid vertikal riktning på tilluftstrålen vid omblandande ventilation - visade avståndet mellan smittkällan och frånluftsdonet ha en effekt på smittspridningen. Detta eftersom överföringssanolikheten varit lägre vid placeringen mitt emot smittkällan och diagonalt från smittkällan vilket är ett större avstånd än vad positionering bredvid smittkällan är. Vad gäller deplacerande ventilation har placeringen av smittkällan visat effekt då överföringssannolikheten varit lägre vid placering av smittkällan närmare frånluftdonet samt att det minsta avståndet från smittkällan i det fallet haft lägst överföringssannolikhet. / This thesis presents the results of an experimental study with the aim to investigate the connection between ventilation in offices and spread of airborne viruses and bacteria. The focus is on coronavirus and this thesis only investigates mixed ventilation and displacement ventilation in the experimental part. The study is done in a full scale mook up room located in Högskolan i Gävle. The aim of the study was to answer how the exposure of airborne diseases change in the breathing zone when the distribution of supply air changes and if placement of the source of infection has any affect. The study also aims to investigate if displacement or mixing ventilation is the best choice to minimize transfer probability from an infected persons breath. Tracer gas measurements was done to answer the main questions. The tracer gas measurements were studied parallel to measurements of air velocities and temperatures on several positions in the room. For mixing ventilation, the measurements were done for two different directions of supply air jet, vertical and horizontal. For displacement ventilation measurements are done for two different temperatures on the supply air which was 21,3 ˚C and 16 ˚C. The results of the experimental part of this study showed that displacement ventilation had a lower transfer probability between an infected person and a non-infected person when compared to mixing ventilation. The transfer probability was 0,3 – 0,5 % for mixing ventilation and 0,1 – 0,3 % for displacement ventilation, which shows that displacement ventilation is generally at a lower level than mixing ventilation regardless of the position of the source of infection. The result in this thesis is like results found in the literature review which also shows that displacement ventilation has a lower tendency to spread infections between persons in the same room. The result for mixing ventilation regarding the direction of the supply air jet showed an impact on the transfer probability. The vertical supply air jet was affecting the force of the breath jet between the thermal manikin placed in front of each other, which is done as part of reduction in the transfer probability at the two different positions for the same direction of the supply air jet. For both ventilation systems – except for the vertical direction of the supply air jet in the case of mixing ventilation - the distance between the source of infection and exhaust diffuser has been shown to have an impact on the transfer probability. This means the transfer probability was lower at the location opposite the source of infection and diagonally from the source of infection, which is a greater distance than the location next to the source of infection. In terms of displacement ventilation, the location of the source of infection has shown an effect as the transfer probability was lower when the source of infection was placed closer to the exhaust diffuser and that the minimum distance from the source of infection in that case was the lowest.