Airborne Samples Research Articles

Determination of allergenic load and pollen count of Cupressus arizonica pollen by flow cytometry using Cup a1 polyclonal antibody.

Background: There is an increase in the incidence of pollen related allergy, thus information on pollen schedules would be a great asset for physicians to improve the clinical care of patients. Like cypress pollen sensitization shows a high prevalence among the causes of allergic rhinitis, and therefore it is of interest to use it like a model of study, distinguishing cypress pollen, pollen count and allergenic load level. In this work, we use a flow cytometry based technique to obtain both Cupressus arizonica pollen count and allergenic load, using specific rabbit polyclonal antibody Cup a1 and its comparison with optical microscopy technique measurement. Methods: Airborne samples were collected from Burkard Spore-Trap and Burkard Cyclone Cupressus arizonica pollen was studied using specific rabbit polyclonal antibody Cup a1, labelled with AlexaFluor® 488 or 750 and analysed by Flow Cytometry in both an EPICS XL and Cyan ADP cytometers (Beckman Coulter® ). Optical microscopy study was realized with a Leica optical microscope. Bland & Altman was used to determine agreement between both techniques measured. Results: We can identify three different populations based on rabbit polyclonal antibody Cup a1 staining. The main region (44.5%) had 97.3% recognition, a second region (25%) with 28% and a third region (30.5%) with 68% respectively. Immunofluorescence and confocal microscopy showed that main region corresponds to whole pollen grains, the second region are pollen without exine and the third region is constituted by smaller particles with allergenic properties. Pollen schedule shows a higher correlation measured by optical microscopy and flow cytometry in the pollen count with a p-value: 0.0008E-2 and 0.0002 with regard to smaller particles, so the Bland & Altman measurement showed a good correlation between them, p-value: 0,0003. Conclusion: Determination of pollen count and allergenic load by flow cytometry represents an important tool in the determination of airborne respiratory allergens. We showed that not only whole pollen but also smaller particles could induce allergic sensitization. This is the first study where flow cytometry is used for calculating pollen counts and allergenic load. © 2013 Clinical Cytometry Society.

Airborne Fungi in Tabriz, Comparing Airborne and Clinical Samples of <italic>A. fumigatus</italic> (2011), Survey and Literature Review

Background: Air contamination with fungal spores and the presence of these spores on respiratory tract, especially in industrialized cities with contaminated air, can play an important role on the occurrence of respiratory and coetaneous mycoses, asthma and allergic reactions. This survey was carried out to determine the prevalence of different fungal spores in the atmosphere of Tabriz district. Objectives: The present study aimed to detect fungal air spores in Tabriz environments, and to compare the environmental samples of Aspergillus fumigatus with the clinical isolated samples of this fungus, due to the importance of the dangers of A. fumigatus for public health, particularly for the immunocompromised patients. Materials and Methods: During this survey, the presence of air fungal spores was analyzed using settle plate and prepared culture in Sabouraud’s dextrose agar. Prior identifications were performed using macroscopic characters, and direct microscopy. 262 samples were collected from different areas of the atmosphere of Tabriz district within all four seasons of the year. Fungal colonies were isolated from all air samples and identified using macroscopic and microscopic characters, and slid culture. Results: The main isolated fungal spores from the atmosphere of Tabriz district were Penicillium Sp. (36.6%), Cladosporidium Sp. (26.8%) and Aspergillus Sp. (23.6%). Conclusions: The presence of fungal spores in the atmosphere as a part of air pollution can cause significant problems for human health, particularly in the respiratory tracts.

Elemental characterization of the airborne pollen surface using Electron Probe Microanalysis (EPMA)

Recent worldwide increase in pollinoses has been attributed to the synergy between pollen and pollutants. We used EPMA for the elemental characterization of the airborne pollen surface in order to find out what occurs to the wall of pollen grains when they are together with other atmospheric pollutants. Analyses were performed both to airborne pollen and to pollen that was collected from Acer spp., Platanus spp. and Pinus spp. trees. Airborne samples were assembled using a Hirst-type volumetric spore sampler set in the coastal city of Porto, Portugal. Airborne pollen samples showed major elemental differences when compared to the control pollen sample of the same species, namely in the amounts of Cl, Na and Mg, which very significantly increased on airborne samples, revealing an important influence of the ocean. Mineral dust also contributed to modify the pollen surface, by increasing Si contents on Acer spp. and Platanus spp. airborne pollen. Our results revealed consistent positive effects of the relative humidity and the precipitation in the increase of Cl, Na and Mg relative amounts on the pollen surface. This study shows that pollen grains have the ability to adsorb and/or absorb other materials, which may contribute to enhance pollen's harmful effects on people's health.

Variable Hf[sbnd]Sr[sbnd]Nd radiogenic isotopic compositions in a Saharan dust storm over the Atlantic: Implications for dust flux to oceans, ice sheets and the terrestrial biosphere

Isotopic characterization of aerosol mineral particles (atmospheric dust) of varying sizes is essential in classifying source areas, and for determining the source of dust deposited over oceans and icesheets. However, the effect of atmospheric transport on radiogenic isotopic compositions is not well constrained, making provenance interpretation difficult. In order to investigate the isotopic variability of 176Hf/177Hf, 87Sr/86Sr and 143Nd/144Nd we analyzed eight airborne dust samples in two size fractions collected along a cross-Atlantic transect through a dust storm originating in the Sahara in late 2002. Past measurements of 176Hf/177Hf, 87Sr/86Sr and 143Nd/144Nd of dust have focused primarily on coarse sized particles (<30μm), whereas far field deposition is primarily finer particles (<2μm). Strontium or neodymium isotopic sorting based on distance is not evident in our dataset; however, the combined isotopic ratios of the dust collected suggest a Saharan origin. Hafnium isotopic compositions show an east to west trend towards more radiogenic compositions across the Atlantic, suggesting grain and mineral sorting during dust transport along the ~4000km transect. Transport models with variable dust particle diameter and wind speed demonstrate the preferential depletion of the high-density mineral zircon during transport of dust from the source area. The transport model combined with a simple two component mixing model show that the Hf isotopic composition changes can be explained by the loss of the mineral zircon during transport. Modeling of this “zircon effect” with distance from the dust source in the Hf isotopic composition of marine, terrestrial and glacial dust deposits may reveal additional information concerning dust transport and sources in the geologic past.

Acid-Soluble Internal Capsules for Closed-Face Cassette Elemental Sampling and Analysis of Workplace Air

Airborne particles that are collected using closed-face filter cassettes (CFCs), which are used widely in the sampling of workplace aerosols, can deposit in places other than on the filter and thereby may not be included in the ensuing analysis. A technique for ensuring that internal non-filter deposits are included in the analysis is to collect airborne particles within an acid-soluble internal capsule that, following sampling, can be dissolved along with the filter for subsequent elemental analysis. An interlaboratory study (ILS) was carried out to evaluate the use of cellulosic CFC capsule inserts for their suitability in the determination of trace elements in airborne samples. The ILS was performed in accordance with an applicable ASTM International standard practice, ASTM E691, which describes statistical procedures for investigating interlaboratory precision. Performance evaluation materials consisted of prototype cellulose acetate capsules attached to mixed-cellulose ester filters. Batches of capsules were dosed with Pb-containing materials (standard aqueous solutions, and certified reference material soil and paint). Also, aerosol samples containing nine target analyte elements (As, Cd, Co, Cr, Cu, Fe, Pb, Mn, and Ni) were generated using a multiport sampler; various concentrations and sampling times were employed to yield samples fortified at desired loading levels. Triplicates of spiked capsules at three different loadings were conveyed to each volunteer laboratory; loading levels were unknown to the participants. The laboratories were asked to prepare the samples by acid dissolution and to analyze aliquots of extracted samples by atomic spectrometry in accordance with applicable ASTM International Standards. Participants were asked to report their results in units of μg of each target element per sample. For the elements investigated, inter-laboratory precision and recovery estimates from the participating laboratories demonstrated the utility of the cellulosic capsule inserts for the measurement of sampled trace elements.

A Comparison of Two Sampling Methods for the Detection of Airborne Methylene Bisphenyl Diisocyanate

The purpose of this study was to determine if there was a significant difference between two readily available sampling methodologies for airborne methylene bisphenyl diisocyanate (MDI), which is an essential precursor in the spray-on truck bed lining industry. Seventy-two personal airborne samples of MDI were collected and analyzed from nine spray-on truck bed liner businesses in northern Colorado. Wide ranges of exposure concentrations were encountered during the spray-on application, including concentrations that exceeded the OSHA permissible exposure limit. The highest airborne MDI concentration measured was 690 ppb. A statistically significant difference between field-desorbed and laboratory-desorbed methods was determined. The field-desorbed sampling methodology yielded consistently higher MDI concentrations than the laboratory-desorbed sampling methodology, which suggests that immediate desorption minimizes isocyanate loss and potential underestimations. Results from the analysis of variance also indicated that different facility factors and environmental conditions within each company, such as the use of ventilation or humidity level, affected the MDI concentrations, indicating the potential for better mitigation of exposures using the hierarchy of controls.

First satellite detection of volcanogenic carbon monoxide

Measuring and tracking the gases that vent from an erupting volcano is a project fraught with potential dangers and difficulties. Taking measurements on the ground places researchers in harm's way, as does taking airborne samples. These approaches also may suffer from issues around accurately representing the spatial and temporal shifts in gas emissions rates. As such, satellite‐based remote sensing techniques are becoming a preferred way to assess the dispersion and concentrations of various volcanic gases. Devising a functional remote sensing scheme, however, depends on identifying a satellite sensor that can reliably identify the chemical species in question and pick the volcanic emissions out from the background concentrations. Such efforts have so far been successful for only a few volcanic gases: sulfuric acid, hydrochloric acid, and hydrogen sulfide.

Airborne and Surface-Bound Microbial Contamination in Two Intensive Care Units of a Medical Center in Central Taiwan

Samples of airborne and surface-bound microbial contamination were taken in two intensive care units of a large-scale medical center. Microbial analyses included total bacterial and fungal loads, as well as the four bacterial species of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii. Among the 114 surface samples taken from seven designated surface locations of room and equipment for each patient, P. aeruginosa was the most frequently detected (19.3%) and most abundant (mean count: 4.18 cfu/plate) bacterium, whereas the respirator represented the most heavily contaminated surface location in both total pathogenic bacteria colony counts (272 cfu) and frequency of positive detection (38.2%). P. aeruginosa also represented the most frequently detected (39.1%, n = 46) and abundant (11.52 ± 17.16 cfu/m^3) bacterium in the air samples (n = 46), and was the only bacterium exhibiting a positive correlation of the mean counts between air and surface samples. The data analysis results further suggested a higher value of relative risk among the infected patients in the presence of the pathogens as compared to those in the absence of them, although the evidence of a of correlation for the individual bacterial species between the environmental samples and infected patients was inconclusive. This study also found that the mean airborne counts and the detection frequencies of these bacteria after patient visitation periods were higher than those before visitation, and that the installation of local air ionizers did not lead to any discernible differences in total bacterial and fungal concentrations.

Characteristics of the transformation frequency at the tumor promotion stage of airborne particulate and gaseous matter at ten sites in Japan

We used a high-volume air sampler in the summer of 2007 and the winter of 2008 at ten Japanese sites (Sapporo, Sendai, Maebashi, Tsukuba, Shinjuku, Sagamihara, Shizuoka, Touhaku, Kitakyushu, and Kagoshima) to collect total suspended particulate (TSP) and gaseous matter for evaluation. We evaluated the transformation frequency at the tumor promotion stage of these samples in a cell transformation assay using Bhas 42 cells, which were established from BALB/c 3T3 cells transfected with the v-Ha-ras oncogene. All samples collected from the gaseous matter were negative for transformed foci. There were several patterns of transformation frequency at the tumor promotion stage by area for the TSP samples. At Sapporo, the transformation frequency at the tumor promotion stage was remarkably higher in winter than in summer as well as in winter at the other sites. At six urban cities from Sendai to Shizuoka, the levels of transformed frequencies per μg of suspended particulates in winter were almost the same, and were higher than those of the remaining three sites. At three sites, Touhaku, Kitakyushu and Kagoshima, the transformation results in winter were judged as negative. The characteristics of the transformed frequencies of the compounds adsorbed on particulate matter at the sampling sites were significant in winter. We also studied the correlation between the transformation frequency at the tumor promotion stage of the TSP samples and the results of quantitative analysis of 16 polyaromatic hydrocarbons (PAHs) at the ten sites. We found that the transformation frequency at the tumor promotion stage of airborne samples could not be predicted based on the quantitative results of the PAHs in those samples. These data suggest that direct risk assessment of air samples with a bioassay is more valuable than quantitative analysis of compounds such as PAHs for predicting carcinogenicity.

Quantification of Phases in Lahore (Pakistan) Airborne Particulates by Matrix-Flushing Method

The mass concentrations of eighteen airborne samples collected from Lahore (Pakistan) are found in the range from 595 to 3027μg/m3with average value of 1130 μg/m3. Most of these values are normal and as reported in the literature for other parts of the world. The major phases identified in the samples by the X-ray powder diffraction technique are Albite (Anorthite), Calcite, Clinochlore (Chlorite), Gypsum, Illite, Quartz and Talc which have also been reported by other researchers to be present in the airborne particulates of other world locations. The average weight percentages of the phases (minerals) in the samples are respectively 15.5, 10.6, 23.7, 2.4, 19.1, 20.2, and 8.5. Some of the elements (e.g., boron, cadmium, lithium, manganese, titanium, and zinc) quantified in two samples determined using a spark-source mass spectrometer appear also to derive their origin from man-made activities. However no compound synthesized in the atmosphere is detected by the X-ray diffraction method.

Monitoring of Solid Particulate Airborne Samples from Mountain Snow in Some Sites of the Alps, Italy

In the last decades, few days a week, several city centres in Italyare closed at vehicular traffic in order to limit the presence of particulate matter, often exceeding the limits set by law [1,2]. The particulate matter have an impact on human health [3,4], in the cultural heritage and natural environment deterioration [5,6]. Many studies have been the carried out in air monitoring in urban areas while the targeted surveys to assess the impact on air quality of snow dispersion for ski activities are rare. Thanks to the Autonomous Province of Trento it has been possible to sample the snowpack in some ski areas inItalyand thanks to stratigraphic profiles it has been possible to observe variations of the chemical composition over time. Natural contribution is strictly related to winds and currents movement, for this reason a deep knowledge of these factors can help in the determination of the prevalent trajectories during the year [7,8]. During a penetrometeric and stratigraphic profile on Presena glacier, the main nivo-meteorological features, air temperature and temperature inside the different layers of the snowpack have been measured. Some snow samples has been collected and analyzed by SEM-EDS, ICP-MS and IC. These qualitative and quantitative analyses allow to obtain chemical and mineralogical composition to define the emitting source.

Inhaled Vaccines for the Prevention of Tuberculosis

Tuberculosis a major challenge to global health exacerbated by emerging multi drug resistant (MDR) and extensively drug resistant (X-DR) strains of M. tuberculosis and co-infection with HIV. BCG, the only approved vaccine, has variable protection ranging between 0-80%. Compared to the large number of new vaccine candidates a modest effort has been expended to investigate other routes of administration, such as pulmonary and intranasal. Vaccination by these routes is relevant since TB infection is mainly acquired by inhalation of a few aerosol droplets containing as little as 3-5 viable bacilli. The lungs have many attractive immunological features including bronchoalveolar lymphoid tissue (BALT) and local antigen presenting cells (APCs) sampling airborne pathogens. Aerosol vaccination is a noninvasive method of antigen delivery that may facilitate mass vaccination campaigns. Administration by non-medical personnel and the ability to eliminate transmission of blood borne diseases arising from poor practice in injected procedures in remote areas is beneficial. The current dogma does not include mucosal immunity for protection against TB but its contribution may not be ruled out. The selection of the appropriate antigen, aerosol formulation and inhaler will determine the success of this approach. Dry powder formulations of antigen/ adjuvant combinations have efficiency of delivery, stability and sterility advantages over liquid formulations. Dry powder vaccines can be manufactured as micro particles and nanoparticles prepared with different materials including polymers, sugars and amino acids. Examples of these novel vaccine formulations and their evaluation in animal models are discussed in the present review. The proposed pharmaceutical and clinical advantages of inhaled dry powder vaccines justify further evaluation.

Domestic Mite Antigens in Floor and Airborne Dust at Workplaces in Comparison to Living Areas: A New Immunoassay to Assess Personal Airborne Allergen Exposure

ObjectivesAllergens produced by domestic mites (DM) are among the most common allergic sensitizers and risk factors for asthma. To compare exposure levels between workplaces and living areas a new assay able to measure airborne DM antigen concentrations was developed.MethodsAt workplaces and in living areas, 213 floor dust samples and 92 personal inhalable dust samples were collected. For sensitive quantification of DM antigens, a new enzyme immunoassay (EIA) based on polyclonal antibodies to Dermatophagoides farinae extract was developed. Reactivity of five house dust mite and four storage mite species was tested. All dust samples were tested with the new EIA and with the Der f 1 and Der p 1-EIAs (Indoor Biotechnologies, UK) which detect major allergens from D. farinae and D. pteronyssinus by monoclonal antibodies. Samples below the detection limit in the DM-EIA were retested in an assay variant with a fluorogenic substrate (DM-FEIA).ResultsThe newly developed DM-EIA detects antigens from all nine tested domestic mite species. It has a lower detection limit of 200 pg/ml of D.farinae protein, compared to 50 pg/ml for the DM-FEIA. DM antigens were detected by DM-EIA/FEIA in all floor dust and 80 (87%) of airborne samples. Der f 1 was found in 133 (62%) floor dust and in only 6 airborne samples, Der p 1 was found in 70 (33%) of floor samples and in one airborne sample. Der f 1 and DM concentrations were highly correlated. DM-antigens were significantly higher in inhalable airborne samples from textile recycling, bed feather filling, feed production, grain storage and cattle stables in comparison to living areas.ConclusionsA new sensitive EIA directed at DM antigens was developed. DM antigen quantities were well correlated to Der f 1 values and were measurable in the majority (87%) of airborne dust samples. Some workplaces had significantly higher DM antigen concentrations than living areas.

Evaluation of airborne particle emissions from commercial products containing carbon nanotubes

The emission of the airborne particles from epoxy resin test sticks with different CNT loadings and two commercial products were characterized while sanding with three grit sizes and three disc sander speeds. The total number concentrations, respirable mass concentrations, and particle size number/mass distributions of the emitted particles were measured using a condensation particle counter, an optical particle counter, and a scanning mobility particle sizer. The emitted particles were sampled on a polycarbonate filter and analyzed using electron microscopy. The highest number concentrations (arithmetic mean = 4670 particles/cm(3)) were produced with coarse sandpaper, 2% (by weight) CNT test sticks and medium disc sander speed, whereas the lowest number concentrations (arithmetic mean = 92 particles/cm(3)) were produced with medium sandpaper, 2% CNT test sticks and slow disc sander speed. Respirable mass concentrations were highest (arithmetic mean = 1.01 mg/m(3)) for fine sandpaper, 2% CNT test sticks and medium disc sander speed and lowest (arithmetic mean = 0.20 mg/m(3)) for medium sandpaper, 0% CNT test sticks and medium disc sander speed. For CNT-epoxy samples, airborne particles were primarily micrometer-sized epoxy cores with CNT protrusions. No free CNTs were observed in airborne samples, except for tests conducted with 4% CNT epoxy. The number concentration, mass concentration, and size distribution of airborne particles generated when products containing CNTs are sanded depends on the conditions of sanding and the characteristics of the material being sanded.

An Examination of Blood Lead Levels in Thai Nielloware Workers

ObjectivesThe objectives of this study were to determine the lead levels in blood samples from nielloware workers, to determine airborne lead levels, to describe the workers' hygiene behaviors, and to ascertain and describe any correlations between lead levels in blood samples and lead levels in airborne samples.MethodsBlood samples and airborne samples from 45 nielloware workers were collected from nielloware workplaces in Nakhon Sri Thammarat Province, Thailand. Lead levels were determined by flame atomic absorption spectrometry (FAAS), at a wavelength of 283.3 nm. FAAS was used especially adequate for metals at relatively high concentration levels.ResultsThe geometric mean of the 45 airborne lead levels was 81.14 µg/m3 (range 9.0-677.2 µg/m3). The geometric mean blood lead level of the 45 workers was 16.25 µg/dL (range 4.59-39.33 µg/dL). No worker had a blood lead level > 60 µg/dL. A statistically significantly positive correlation was found between airborne lead level and blood lead levels (r = 0.747, p < 0.01). It was observed that personal hygiene was poor; workers smoked and did not wash their hands before drinking or eating. It was concluded that these behaviors had a significant correlation with blood lead levels (p < 0.001).ConclusionImprovements in working conditions and occupational health education are required due to the correlation found between blood leads and airborne lead levels.

Assessment of chemical and mineralogical characteristics of airborne dust in the Sistan region, Iran

Windblown transport and deposition of dust is widely recognized as an important physical and chemical concern to climate, human health and ecosystems. Sistan is a region located in southeast Iran with extensive wind erosion, severe desertification and intense dust storms, which cause adverse effects in regional air quality and human health. To mitigate the impact of these phenomena, it is vital to ascertain the physical and chemical characteristics of airborne and soil dust. This paper examines for the first time, the mineralogical and chemical properties of dust over Sistan by collecting aerosol samples at two stations established close to a dry-bed lake dust source region, from August 2009 to August 2010. Furthermore, soil samples were collected from topsoil (0–5cm depth) at several locations in the dry-bed Hamoun lakes and downwind areas. These data were analyzed to investigate the chemical and mineralogical characteristics of dust, relevance of inferred sources and contributions to air pollution. X-ray Diffraction (XRD) analysis of airborne and soil dust samples shows that the dust mineralogy is dominated mainly by quartz (30–40%), calcite (18–23%), muscovite (10–17%), plagioclase (9–12%), chlorite (∼6%) and enstatite (∼3%), with minor components of dolomite, microcline, halite and gypsum. X-ray Fluorescence (XRF) analyses of all the samples indicate that the most important oxide compositions of the airborne and soil dust are SiO2, CaO, Al2O3, Na2O, MgO and Fe2O3, exhibiting similar percentages for both stations and soil samples. Estimates of Enrichment Factors (EFs) for all studied elements show that all of them have very low EF values, suggesting natural origin from local materials. The results suggest that a common dust source region can be inferred, which is the eroded sedimentary environment in the extensive Hamoun dry lakes lying to the north of Sistan.

Allergens in urban schools and homes of children with asthma

Most studies of indoor allergens have focused on the home environment. However, schools may be an important site of allergen exposure for children with asthma. We compared school allergen exposure to home exposure in a cohort of children with asthma. Correlations between settled dust and airborne allergen levels in classrooms were examined. Settled dust and airborne samples from 12 inner-city schools were analyzed for indoor allergens using multiplex array technology (MARIA). School samples were linked to students with asthma enrolled in the School Inner-City Asthma Study (SICAS). Settled dust samples from students' bedrooms were analyzed similarly. From schools, 229 settled dust and 197 airborne samples were obtained. From homes, 118 settled dust samples were obtained. Linear mixed regression models of log-transformed variables showed significantly higher settled dust levels of mouse, cat and dog allergens in schools than homes (545% higher for Mus m 1, estimated absolute difference 0.55 μg/g, p < 0.0001; 198% higher for Fel d 1, estimated absolute difference 0.13 μg/g, p = 0.0033; and 144% higher for Can f 1, estimated absolute difference 0.05 μg/g, p = 0.0008). Airborne and settled dust Mus m 1 levels in classrooms were moderately correlated (r = 0.48; p < 0.0001). There were undetectable to very low levels of cockroach and dust mite allergens in both homes and schools. Mouse allergen levels in schools were substantial. In general, cat and dog allergen levels were low, but detectable, and were higher in schools. Aerosolization of mouse allergen in classrooms may be a significant exposure for students. Further studies are needed to evaluate the effect of indoor allergen exposure in schools on asthma morbidity in students with asthma.

충북지역 폐석면광산 인근주민의 석면노출과 건강위해도 평가

To investigate the exposure and health risk assessment for the residents near the D-asbestos mine in Chungbuk, Korea. We analyzed asbestos in the 20 ambient air and 23 activity based samples near the mine. The airborne sample results are showed that 8 of 20 samples ranged between 0.0025 to 0.0029 f/cc (fiber per cubic centimeter) and the others were below the detection limit by phase contrast microscopy (PCM). In addition, asbestos fibers were under the detection limit or not being by transmission electron microscopy (TEM). Based on interview and survey targeting the local residents, we made the activity based sampling (ABS) scenarios fit to the conditions of field. At the same time, we calculated the excess lifetime cancer risk (ELCR) of these ABS scenarios according to the ELCR average value and 95% upper confidence limit (UCL). At the case of weed whacking, soil digging and sweeping yard scenario, 95% UCL of ELCR exceeded the , acceptable risk range for exposure. Based on our study results, it is necessary safety measures such as risk communication, abatement or management of naturally occurring asbestos (NOA).

Endotoxin exposure in inner-city schools and homes of children with asthma

BackgroundEndotoxins are stimulators of the immune system and, despite their potential to protect against allergy, have been associated with early wheezing and asthma morbidity. ObjectiveTo compare inner-city school endotoxin exposure with home endotoxin exposure in children with asthma. MethodsStudents with asthma were recruited from 12 urban elementary schools. Settled and airborne dust samples, linked to enrolled students, were collected from school classrooms, gymnasiums, and cafeterias twice during the academic year. For comparison, settled dust was collected once from the bedrooms of students with asthma. ResultsTwo hundred twenty-nine school settled dust samples and 118 bedroom settled dust samples were collected and analyzed for endotoxin. The median endotoxin concentration for school samples was 13.4 EU/mg (range, 0.7–360.7 EU/mg) and for home samples was 7.0 EU/mg (range = LLOD–843.0 EU/mg). The median concentration within each individual school varied from 6.6 EU/mg to 24.0 EU/mg. One hundred four students with asthma had matched classroom and bedroom endotoxin exposure measurements performed in the same season and demonstrated significantly higher concentrations of endotoxin in the students' classrooms (mean log value, 1.13 vs 0.99, P = .04). The median of the classrooms was 12.5 EU/mg compared with their bedrooms, with a median of 7.0 EU/mg. Within the school environment, no significant difference was seen between the fall and spring samples (mean log value 1.14 vs 1.09; P = .35). ConclusionInner-city children with asthma were exposed to higher concentrations of endotoxin in their classrooms as compared with their bedrooms. Further studies are needed to evaluate school endotoxin exposure as a factor in asthma morbidity.

Development of a PM2.5 sampler with inertial impaction for sampling airborne particulate matter

A simple and low cost PM2.5 impactor for sampling airborne particulate matter was developed, designed and evaluated. The design was an assembly of an acceleration nozzle and an impaction plate. Particles with sufficient inertia were unable to follow air streamlines and impacted on the plate. Smaller particles followed the streamlines, avoided being captured by the plate and could then be collected on a downstream filter. Analytical and numerical models were formulated to predict collection efficiency, flow fields and vectors, and particle trajectories in the impactor. The modeling suggested that an optimal operational domain exists for the PM2.5 impactor. A prototype was then built and tested. The collected particles on the impaction plate and downstream of the PM2.5 impactor were analyzed by using scanning electron microscopy. Experimental results agreed well with the theoretical predictions. Testing of the PM2.5 impactor prototype showed promising results for this airborne particulate matter sampler.