A timed exposure diffusive sampler (TEDS) sensitive enough to measure hourly averages of nitrogen dioxide (NO2) at low parts per billion levels was developed for use in epidemiological studies. TEDS can be used for a variety of atmospheric pollutants. TEDS was tested in the laboratory against known concentrations of NO2 and against well established NO2 measurement systems. It was then tested in the field against the Environmental Protection Agency's reference method for measuring NO2. The TEDS method appears well suited to epidemiological investigations of air quality and extends previous work in this area by offering improved time resolution of changes in pollutant concentration at a cost sufficiently low to permit its use in large scale studies. The TEDS method also shows potential for miniaturization for use in personal sampling.

In February 1994, EPA proposed to "refine" its carbon monoxide (CO) hot spot model, CAL3QHC, to increase its accuracy and reliability. Currently, this proposal includes using hourly meteorological data recorded at airports near the modeling sites instead of the worst case conditions now recommended as a modeling default. The analysis in this study has shown that airport data should be used only on a situational basis as discrepancies exist between airports and local intersections. It is unclear if the added meteorological data will improve CAL3QHC's performance. This study also compares actual CO concentrations and their corresponding meteorology with the worst case modeling defaults. The highest CO levels are occurring at calms (wind speed less than one meter per second) which are not able to be modeled with the current Gaussian dispersion equation in CAL3QHC. Given the findings of this analysis and the lack of other scientific evidence supporting the proposed refinements, recommendations for developing an alternative model improvement plan are outlined. / Graduation date: 1995

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xv, 134 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 133-134).

Thesis (Ph. D.)--Oregon Graduate Institute, 2000.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Doctor of Philosophy(PhD), / Airborne fungi are ubiquitous in the environment and human exposure is inevitable. Such fungi differ greatly in their taxonomic, physical, ecological and pathogenic characteristics. Currently, 69 000 species have been taxonomically classified and more than 80 of these are recognised to be aeroallergen sources. Many strategies have evolved to sample, identify and interpret fungal exposure to these species, however no strategy serves all purposes as exposure is a complex and dynamic process confounded by spatial, temporal and geographic variations in airborne counts, in addition to the inadequacies of the immunodiagnostic techniques available. To date, the interpretation of personal exposure and sensitisation to fungal allergens has been restricted to a few select species and the contribution of other genera, airborne hyphae and fragmented conidia to allergic disease are all poorly understood. The aim of the thesis was to utilize the Halogen Immunoassay (HIA) to diagnose fungal allergic sensitisation, to investigate the distribution and factors influencing allergens of fungi in the air and to understand what is actually inhaled in exposure settings. The novelty of the HIA derives from its unique ability to provide allergen sources that are actively secreted by the collected fungal spores and hyphae, which are bound to protein binding membranes (PBM) and then immunoprobed. In Chapter 2, the HIA was compared to the commercial in vitro Pharmacia UniCap assay (CAP) and the in vivo skin prick test (SPT), using 30 sera from subjects SPT positive to Aspergillus fumigatus and/or Alternaria alternata and 30 who were SPT negative to these fungi but sensitised to non-fungal allergens. Sera were analysed by CAP and the HIA against A. alternata, A. fumigatus, Cladosporium herbarum and Epicoccum purpurascens and compared statistically. Between 3% and 7% of SPT negative sera were identified to have specific IgE towards A. fumigatus and A. iv alternata, respectively. For the SPT positive sera, significant associations were found between the HIA and CAP scores for all fungal species tested (P<0.0001). Correlations between the HIA and SPT however, were weakly correlated for A. alternata (rs = 0.44, P<0.05) but not for A. fumigatus. In Chapter 3, personal exposure to indoor fungal aerosols was examined using the HIA to identify the fungal components that people were allergic to. Personal air sampling pumps (PASs) collected airborne fungal propagules onto PBMs for 2.5 hours indoors (n=21). Collected fungi were incubated overnight in a humid chamber to promote the germination of conidia. The membranes were then immunostained with pooled human Alternaria species-positive sera. All air samples contained fungal hyphae that expressed soluble allergens and were significantly higher in concentration than counts of conidia of individual well-characterised allergenic genera. Approximately 25% of all hyphae expressed detectable allergen compared to non-stained hyphae (P<0.05) and the resultant localisation of immunostaining was heterogeneous among hyphae. Fungal conidia of ten genera that were previously uncharacterised as allergen sources accounted for 8% of the total conidia that demonstrated IgE binding. In Chapter 4, the number and identity of fungi inhaled by 34 adults in an outdoor community setting was measured over 2 hour periods by people wearing Intra-nasal air samplers (INASs) and compared to fungal counts made with a Burkard spore trap and filter air samplers worn on the lapel. Using INAS, the most prevalent fungi inhaled belonged to soil borne spores of Alternaria, Arthrinium, Bipolaris, Cladosporium, Curvularia, Epicoccum, Exserohilum, Fusarium, Pithomyces, Spegazzinia, Tetraploa and Xylariaceae species, in addition to hyphal fragments. These results showed that inhaled exposure in most people varied in a 2-fold range with 10-fold outliers. In addition, the INAS and personal air filters agreed more with each other than with Burkard spore trap counts. The analysis was further confounded by different sampling efficiencies, locations of devices and ability to visualise and count fungal propagules. In Chapter 5, a double immunostaining technique based on the HIA was developed and applied to the conidia, hyphae and fungal fragments of A. alternata, A. fumigatus and Penicillium chrysogenum to discriminate between sources of allergens, v using IgE and to identify the fungi, using a fungal-specific antibody. The localisation of immunostaining was heterogeneous between both conidia and the state of germination with greater concentrations of double immunostaining detected following germination for each fungal species (P<0.0001). Fragmented A. alternata hyphae and morphologically indiscernible fragments could be identified for the first time using this technique. In Chapter 6, the factors affecting the release of allergen from the spores of eleven different species were studied. For nine of eleven species, between 5.7% and 92% of spores released allergen before germination. Ungerminated spores of P. chrysogenum and Trichoderma viride did not release detectable allergen. After germination, all spores that germinated eluted allergen from their hyphae. Upon germination there was a significant increase in the percentage of spores eluting detectable allergen (P<0.0001) and the localisation of allergen along the hyphae varied between species. Increased elution of allergen post germination might be a common feature of many species of allergenic fungi following inhalation. Additionally, Chapter 6 explored the extent to which inhaled spores or hyphae germinate after deposition in the nasal cavity and thus cause exposure to allergens. Twenty subjects had their noses lavaged at three separate intervals, (1) at the beginning of the experiment, (2) after one hour indoors and (3) after one hour outdoors. The recovery of spores and hyphal fragments from the nasal cavity varied between individuals and was significantly greater after outdoor exposures. Germinated fungal spores were recovered often in high concentrations for Aspergillus-Penicillium species, however the proportion between ungerminated and germinated spores were much lower for other genera recovered. Conclusions: Our analysis of cultured and wild-type fungi presents a new paradigm of natural fungal exposure, which in addition to commonly recognized species, implicates airborne hyphae, fragmented conidia and the conidia of a much more diverse range of genera as airborne allergens. Exposure is heterogeneous between individuals in the same geographic locality and the spectrum of fungal genera inhaled differs with the method of analysis. Many of the spores inhaled are likely to be allergenic, however upon germination there is an increased elution of allergen and this might be a common vi feature of many fungal species following inhalation. This project also provides novel techniques to diagnose fungal allergy by immunostaining wild-type fungi to which a patient is exposed with the patient’s own serum. Such an immunoassay combines environmental with serological monitoring on a patient specific basis and potentially avoids many problems associated with extract variability, based on the performance of current diagnostic techniques for fungal allergy.

Across Canada, and around the world, very large amounts of pesticides are produced and applied to agricultural crops each year. Although pesticide usage is declining, they are still a necessary part of industrial agriculture. Numerous pesticides have been quantified in the atmosphere, at high levels near regions of use and at lower, but still significant levels in remote regions. Some of the most persistent pesticides have been banned, but others continue to be used despite their persistence and potential for long-range transport (LRT). We have applied and refined an XAD-2 resin-based passive air sampler (PAS) to study the concentrations of pesticides in the atmosphere. A set of laboratory experiments measured the equilibria sorption coefficients for chemicals on XAD-2 resin, allowing the determination of a new predictive equation for equilibria sorption coefficients, and thus interpretation of the range of applicability of both XAD-based PAS and active air samplers (AAS). A set of field experiments were performed to compare the data obtained by both PAS and AAS, and to study the temporal trends of a wide range of pesticides in an agricultural area of southern Ontario. Because it is now apparent that XAD-PAS sampling rates can vary between compounds and with temperature, we also determined new compound-specific sampling rates for pesticides in the XAD-PAS. The XAD-PAS were deployed in two transects across Canada, one from the Great Lakes region to the Canadian Arctic, and one across southern British Columbia in four different mountain regions and at different elevations. The air concentrations of current-use pesticides were correlated with regions of their use in both transects. The variation of air concentration with elevation was correlated with local, ground-level sources in British Columbia. The LRT of pesticides was determined from the north-south transect, and correlated to their atmospheric half-lives. Historic-use pesticides such as hexachlorobenzene and hexachlorocyclohexane were found to have relatively uniform distributions in the Canadian atmosphere, while further evidence of α-hexachlorocyclohexane evaporation from oceans was observed in both transects.

Across Canada, and around the world, very large amounts of pesticides are produced and applied to agricultural crops each year. Although pesticide usage is declining, they are still a necessary part of industrial agriculture. Numerous pesticides have been quantified in the atmosphere, at high levels near regions of use and at lower, but still significant levels in remote regions. Some of the most persistent pesticides have been banned, but others continue to be used despite their persistence and potential for long-range transport (LRT). We have applied and refined an XAD-2 resin-based passive air sampler (PAS) to study the concentrations of pesticides in the atmosphere. A set of laboratory experiments measured the equilibria sorption coefficients for chemicals on XAD-2 resin, allowing the determination of a new predictive equation for equilibria sorption coefficients, and thus interpretation of the range of applicability of both XAD-based PAS and active air samplers (AAS). A set of field experiments were performed to compare the data obtained by both PAS and AAS, and to study the temporal trends of a wide range of pesticides in an agricultural area of southern Ontario. Because it is now apparent that XAD-PAS sampling rates can vary between compounds and with temperature, we also determined new compound-specific sampling rates for pesticides in the XAD-PAS. The XAD-PAS were deployed in two transects across Canada, one from the Great Lakes region to the Canadian Arctic, and one across southern British Columbia in four different mountain regions and at different elevations. The air concentrations of current-use pesticides were correlated with regions of their use in both transects. The variation of air concentration with elevation was correlated with local, ground-level sources in British Columbia. The LRT of pesticides was determined from the north-south transect, and correlated to their atmospheric half-lives. Historic-use pesticides such as hexachlorobenzene and hexachlorocyclohexane were found to have relatively uniform distributions in the Canadian atmosphere, while further evidence of α-hexachlorocyclohexane evaporation from oceans was observed in both transects.

Indoor air quality investigations often focus on air and settled dust samples to assess chemical and biological contamination. Although the information provided by these techniques is useful, HVAC filters represent a new option for investigating contaminants in the indoor environment. This dissertation explores the potential use of HVAC filters as long-term, passive samplers by investigating the contaminants found in HVAC dust and other indoor locations and by evaluating the likelihood that HVAC filters will capture indoor particles. A field investigation of heavy metal and culturable microbial contaminants found in air, settled dust and HVAC filter dust corroborated the hypothesis that HVAC filters hold promise as a sampling mechanism in residences. However, several factors including filter efficiency, HVAC cycling and particle size seemed to influence the results. Also, it was unclear how the composition of the microbial communities varied with sampling location. Subsequently, the bacterial and fungal communities present in several sampling locations within residences and in an unoccupied test house were investigated. In residences, the microbial communities encountered in HVAC filter dust were not different from those in high surface dust. High efficiency HVAC filters also seem to be a viable alternative to long-term air sampling. Occupants influence the composition of the microbial communities in residences and are viii associated with Actinobacteria and Firmicutes, while Proteobacteria dominate the air samples and might have an outdoor air origin. A fate analysis to assess the magnitude of the different particle removal mechanisms revealed that small and large particles are likely to deposit on surfaces, while intermediate sized particles stay suspended in air longer. HVAC filters can collect particulate matter over a broad size range and may be effective overall samplers of particle-bound contaminants. Nevertheless, filter efficiency and air recirculation rate are important parameters that influence the likelihood that filters will capture particles, while air exchange rate has little effect. The results from this study indicate that HVAC filters can be used as an alternative to traditional indoor sampling mechanisms for contaminants associated with particles.

No description available.