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Information about the co-occurrence of halogenated flame retardants (HFRs) and organophosphate esters (OPEs) in the environment of informal waste processing areas is still limited, especially in emerging and developing countries. In this study, OPEs and HFRs including polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), and chlorinated flame retardants (CFRs) were determined in settled dust from Vietnamese e-waste recycling (WR) and vehicle processing (VP) workshops. Pollutant concentrations decreased in the order: OPEs (median 1500; range 230–410,000 ng/g) ≈ PBDEs (1200; 58–250,000) > NBFRs (140; not detected – 250,000) > CFRs (13; 0.39–2200). HFR and OPE levels in the WR workshops for e-waste and obsolete plastic were significantly higher than in the VP workshops. Decabromodiphenyl ether and decabromodiphenyl ethane are major HFRs, accounting for 60 ± 26% and 25 ± 29% of total HFRs, respectively. Triphenyl phosphate, tris(2-chloroisopropyl) phosphate, and tris(1,3-dichloroisopropyl) phosphate dominated the OPE profiles, accounting for 30 ± 25%, 25 ± 16%, and 24 ± 18% of total OPEs, respectively. The OPE profiles differed between WR and VP dust samples, implying different usage patterns of these substances in polymer materials for electric/electronic appliance and automotive industries. Human health risk related to dust-bound HFRs and OPEs in the study areas was low. [Display omitted] • Pollutant levels in dust were in the order: PBDEs ≈ OPEs > NBFRs > CFRs. • Informal e-waste recycling activities were potential source of HFRs and OPEs. • BDE-209, DBDPE, and TPHP were major compounds in e-waste recycling sites. • Vehicle workshop dust had low HFR levels and specific OPE profiles. • OPE sources and emission from vehicle processing should be further investigated. [ABSTRACT FROM AUTHOR]

Previous studies have shown elevated airborne manganese (Mn) in villages adjacent to a Mn alloy production plant in Brazil and negative associations between biomarkers of Mn and children's cognition and behavior. Since small Mn particles may be carried for long distances, we measured manganese (Mn) and lead (Pb) dust fall accumulation in 15 elementary schools, located between 1.25 and 6.48 km from the plant in the municipality of Simões Filho, Bahia, Brazil. Passive samplers (polyethylene Petri dishes) were set in interior and exterior environments. After 30 days, the samplers’ content was solubilized with diluted nitric acid and Mn and Pb levels were analyzed by electrothermal absorption spectrometry. The overall geometric mean and range of Mn and Pb accumulation in dust fall (loading rates) were 1582 μg Mn/m 2 /30 days (37–37,967) and 43.2 μg Pb/m 2 /30 days (2.9–210.4). A logarithmic decrease in interior and exterior Mn loading rates was observed with distance from the ferro-manganese alloy plant. Multiple regression analyses of log-transformed Mn loading rate within the schools showed a positive association with Mn levels in outdoor dust, a negative association with distance from the plant; as well, wind direction (downwind>upwind) and school location (urban>rural) entered significantly into the model. For the interior school environments, located within a 2-km radius from the plant, loading rate was, on average, 190 times higher than the Mn levels reported by Gulson et al., (2014) in daycare centers in Sydney, Australia, using a similar method. Pb loading rates were not associated with distance from the plant and were lower than the rates observed in the same daycare centers in Sydney. Our findings suggest that a significant portion of the children in this town in Brazil may be exposed to airborne Mn at concentrations that may affect their neurodevelopment. [ABSTRACT FROM AUTHOR]

Aiming to identify factors causing the adverse health effects associated with moisture-damaged indoor environments, we analyzed immunotoxicological potential of settled dust from moisture-damaged and reference schools in relation to their microbiological composition. Mouse RAW264.7 macrophages were exposed to settled dust samples ( n = 25) collected from moisture-damaged and reference schools in Spain, the Netherlands, and Finland. After exposure, we analyzed production of inflammatory markers [nitric oxide ( NO), tumor necrosis factor- α ( TNF-) α, interleukin ( IL)-6, and macrophage inflammatory protein ( MIP)2] as well as mitochondrial activity, viability, apoptosis, and cell cycle arrest. Furthermore, particle counts, concentration of selected microbial groups as well as chemical markers such as ergosterol, 3-hydroxy fatty acids, muramic acid, endotoxins, and glucans were measured as markers of exposure. Dust from moisture-damaged schools in Spain and the Netherlands induced stronger immunotoxicological responses compared to samples from reference schools; the responses to Finnish samples were generally lower with no difference between the schools. In multivariate analysis, IL-6 and apoptosis responses were most strongly associated with moisture status of the school. The measured responses correlated with several microbial markers and numbers of particles, but the most important predictor of the immunotoxicological potential of settled dust was muramic acid concentration, a marker of Gram-positive bacteria. [ABSTRACT FROM AUTHOR]

Dust is an important sink for indoor air pollutants, such as polychlorinated biphenyls (PCBs) that were used in building materials and products. In this study, two types of dust, house dust and Arizona Test Dust, were tested in a 30-m 3 stainless steel chamber with two types of panels. The PCB-containing panels were aluminum sheets coated with a PCB-spiked primer or caulk. The PCB-free panels were coated with the same materials but without PCBs. The dust evenly spread on each panel was collected at different times to determine its PCB content. The data from the PCB panels were used to evaluate the PCB migration from the source to the dust through direct contact, and the data from the PCB-free panels were used to evaluate the sorption of PCBs through the dust/air partition. Settled dust can adsorb PCBs from air. The sorption concentration was dependent on the congener concentration in the air and favored less volatile congeners. When the house dust was in direct contact with the PCB-containing panel, PCBs migrated into the dust at a much faster rate than the PCB transfer rate due to the dust/air partition. The dust/source partition was not significantly affected by the congener's volatility. For a given congener, the ratio between its concentration in the dust and in the source was used to estimate the dust/source partition coefficient. The estimated values ranged from 0.04 to 0.16. These values are indicative of the sink strength of the tested house dust being in the middle or lower-middle range. [ABSTRACT FROM AUTHOR]

Objectives: To date, the scientific source materials usually focus on microbial contamination of the museum or library collections themselves, while the exposure of persons who professionally deal with this type of objects in cultural heritage conservation laboratories is ignored.Material and Methods: The study was carried out in 9 naturally ventilated conservation laboratories with no history of water damage. Viable (understood as culturable) bioaerosol stationary samples were collected in both outdoor and indoor environments using 6-stage Andersen impactor. Simultaneously, stationary and personal indoor bioaerosol measurements were carried out using both Gesamtstaubprobenahme an der Person (GSP) and Button filter samplers. These measurements were complemented by evaluation of microbial content in the dust settled on conserved works of art. All impactor, filter, and settled dust samples were quantitatively examined to obtain viable and total concentrations of bacteria and fungi. All isolated microbial strains were taxonomically identified.Results: At workplaces, the concentrations of viable microorganisms in air were below 2000 cfu/m3 and accounted for not more than 5.5% of total microbiota. The study showed that quantitative assessment of viable bioaerosol can be made with an Andersen impactor as well as by using Button and GSP filter samplers, irrespective of whether they are applied for personal or stationary measurements. Compared to the impactor, however, the use of filter samplers for microbial contamination monitoring substantially limits the scope of qualitative information which can be obtained. Size distribution analysis revealed that the largest "load" of microorganisms can penetrate into the respiratory tract between the trachea and terminal bronchi, and thereby may be responsible for allergic inflammations in exposed workers.Conclusions: The precise assessment of microbial hazards in conservation laboratories should comprise control of both viable and total particle counts. The hermetization of such workplaces and control of relative humidity should be implemented and maintained to assure proper hygienic conditions. [ABSTRACT FROM AUTHOR]

The aim of this study was to characterise the contamination in settled dust in French classrooms and to provide an overview of the influencing factors of dust contamination. Cat, dog and dust mite allergens and metals were measured in 51 classrooms at 17 schools. The concentrations of pet allergens in settled dust were generally low (mean value of 0.1 μg.g-1), with carpeted and rug-covered floors presenting higher dust and cat allergen concentrations. The highest metal loadings in dust were observed for manganese (Mn) and copper (Cu), while the lead (Pb) loadings were lower (16 ± 19 μg.m-2) and fell below the French guideline. Higher metal leachability was found for cadmium (Cd), Cu, Pb and strontium (Sr) at values of approximately 80%, which suggest that, in cases of dust ingestion by children, a large proportion should be assimilated through the gastro-intestinal tract. The intra-classroom and intra-school variabilities of the metal concentrations in settled dust were lower than the variability between schools. Classrooms with tiled floors had higher Pb loadings than classrooms with wood or vinyl floors. In addition, wet cleaning less than once a week resulted in greater loadings of Cu and Pb in the settled dust. Lastly, enrichment factors showed that metals in settled dust of classrooms were not only from the contribution of the natural background concentrations in soils. [ABSTRACT FROM AUTHOR]

Indoor air in homes contains a variety of organic agents such as bacteria, endotoxin and fungi. Epidemiological studies have shown links between these components and respiratory problems and the development of allergies. Twenty-eight dwellings located in the Greater Copenhagen area in Denmark were investigated in this study. Temperature, relative humidity and air exchange rate were measured. Dwelling characteristics including floor area, volume of the living room, floor material, year of construction of buildings and floor level were collected. The microbial exposure was measured by quantifying fungi, bacteria and endotoxin concentration in airborne dust collected by Electrostatic Dust fall Collectors (EDCs). The Total Inflammatory Potential (TIP) of the dust was also measured. Significantly higher concentrations of fungi were found in dwellings with high relative humidity (p = 0.03), larger room volume (p = 0.03) and in dwellings located on the second floor or higher (p = 0.02). Small floor area per person and low air exchange rate were significantly associated with increased concentrations of bacteria (both p < 0.01). Spring season (p = 0.01), buildings constructed before the 20th century (p = 0.09) and wooden floor (p = 0.03) were associated with high TIP. In conclusion, people living in smaller dwellings or in dwellings on upper floors are at higher risk of microbial exposure. While TIP was affected by some dwelling characteristics, it was mainly influenced by season. [ABSTRACT FROM AUTHOR]

Due to their low vapor pressure, semi-volatile organic compounds (SVOCs) can absorb onto other compartments in indoor environments, including settled dust. Incidental ingestion of settled dust-bound SVOCs contributes to the majority of daily non-dietary exposure to some SVOCs by human beings. With this pathway in mind, an integrated kinetic model to estimate indoor SVOC was developed to better predict the mass-fraction of SVOC associated with settled dust, which is important to accurately assess the non-dietary ingestion exposure to SVOC. In this integrated kinetic model, the aerosol dynamics were considered, including particle penetration, deposition and resuspension. The newly developed model was evaluated by comparing the predicted mass-fraction of SVOC associated with the settled dust ( X dust ) and the measured X dust from previous studies. Sixty X dust values of thirty-eight different SVOCs measured in residences located in seven countries from four continents were involved in the model evaluation. The X dust value predicted by the integrated kinetic model correlated linearly with the measured X dust : y = 0.93x + 0.09 ( R 2 = 0.73), which indicates that the predicted X dust by the integrated kinetic model are in good match with the measured data. This model may be utilized to predict SVOC concentrations in different indoor compartments, including dust-bound SVOC. [ABSTRACT FROM AUTHOR]

This paper describes a method for dynamic modelling of the interactions of semivolatile organic compounds (SVOCs) with airborne and settled particulate matter in the indoor environment. As part of the framework for dynamic modelling of indoor SVOCs recently proposed by this author, this method is fully compatible with the other components in the framework. With reduced computational complexity, the method is more flexible than the existing dynamic models. Despite the uncertainties in some of the key parameters, the simulation results have revealed important information regarding the general behaviour of SVOC-particle interactions and the role of particulate matter in human exposure to indoor SVOCs. [ABSTRACT FROM AUTHOR]

Objectives: The study was aimed at assessment of exposure to endotoxins, (1→3)-β-D-glucans and mite, cockroach, cat, dog allergens present in settled dust in premises of children as agents which may be significantly correlated with the occurrence of allergic symptoms and diseases in children. Materials and Methods: The study covered 50 homes of one-or two-year-old children in Poland. Samples of settled dust were taken from the floor and the child's bed. The levels of (1→3)-β-D-glucans (floor), endotoxins (floor) and allergens of mite, cat, dog and cockroach (floor and bed) were analyzed. Results: Average geometric concentrations (geometric standard deviation) of endotoxins, (1→3)-β-D-glucans, Der p1, Fel d1, Can f1 and Bla g1 in children homes were on the floor 42 166.0 EU/g (3.2), 20 478.4 ng/g (2.38), 93.9 ng/g (6.58), 119.8 ng/g (13.0), 288.9 ng/g (3.4), 0.72 U/g (4.4) and in their beds (only allergens) 597.8 ng/g (14.2), 54.1 ng/g (4.4), 158.6 ng/g (3.1) 0.6 U/g (2.9), respectively. When the floor was covered with the carpet, higher concentrations of endotoxins, (1→3)-β-D-glucans and allergens (each type) were found in the settled dust (p < 0.05). The trend was opposite in case of allergens (except dog) analyzed from bed dust and significantly higher concentrations were found in the rooms with smooth floor (p < 0.05). Conclusions: Among the analyzed factors only the type of floor significantly modified both the level of biological indicators and allergens. The results of this study could be the base for verifying a hypothesis that carpeting may have a protective role against high levels of cockroach, dog and cat allergens. [ABSTRACT FROM AUTHOR]

Objectives: The main objective of the study was to determine the levels of house dust mite (Der p1), dog (Can f1), cat (Fel d1) and cockroach (Bla g2) allergens in kindergartens localized in an urban agglomeration. Material and Methods: A quantitative analysis of allergens was carried out in settled dust samples collected by vacuuming the floor surface in three kindergartens (N = 84) and children's clothing (N = 36). The samples were collected in spring-summer and autumn-winter periods as well as at the beginning and end of the week. The allergen dust concentration was determined by enzyme-linked immunoenzymatic assay (ELISA). Results: The mean geometric concentrations (±geometric standard deviations) of allergens Der p1, Can f1, Fel d1 and Bla g2 determined in kindergartens were: 0.02±3.21 μg/g of dust; 0.97±4.49 μg/g of dust; 0.30±4.43 μg/g of dust and 0.01±3.08 μg/g of dust, respectively. Younger classrooms (children aged from 3 to 4 years) were characterized by almost twice higher mean concentration of allergen Fel d1, as compared to older classrooms (children aged from 5 to 6 years) (p < 0.05). A significant impact of seasonality on the level of dog allergen Can f1 was found (p < 0.05). No significant weekly variation was found in average concentrations of the allergens. Children who had a dog and/or cat at home were characterized by high concentrations of allergens Can f1 and Fel d1 on their clothes (59.2±5.39 μg Can f1/g of dust; 3.63±1.47 μg Fel d1/g of dust), significantly higher than concentrations of allergens in children who did not have any pets (p < 0.001). Conclusions: Special attention should be paid to keeping the kindergarten rooms tidy and clean and to an appropriate choice of furnishings and fittings which would prevent the proliferation of the house dust mite and accumulation of allergens. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the potential contamination of SARS-CoV-2 in indoor settled dust and surfaces of Amir Al-Muminin hospital in Maragheh, Iran. Samples were taken from surfaces and settled dust using a passive approach and particulate matter (PM) using an active approach from different hospital wards. SARS-CoV-2 was detected in 15% of settled dust samples (N = 4/26) and 10% of surface samples (3/30). SARS-CoV-2 has been detected in 13.8% and 9.1% of the dust samples collected at a distance of fewer than 1 m and more than 3 m from the patient bed, respectively. SARS-CoV-2 was found in 11% of surface samples from low-touch surfaces and 8% from high touch surfaces. The relationship between PM 2.5 , PM 10 , humidity, temperature, and positive samples of SARS-CoV-2 was investigated. A positive correlation was observed between relative humidity, PM 2.5 , and positive SARS-CoV-2 samples. Principal component analysis (PCA) suggested positive correlation between positive SARS-CoV-2 samples, relative humidity, and PM 2.5 . Risk assessment results indicated that the annual mean infection risk of SARS-CoV-2 for hospital staff with illness and death was 2.6 × 10 -2 and 7.7 × 10 -4 per person per year. Current findings will help reduce the permanence of viral particles in the COVID 19 tragedy and future similar pandemics e.g., novel influenza viruses., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved.)

Phthalates (PAEs) are pervasive in indoor environments. In this study, two migration pathways of di-n-octyl phthalate (DNOP) from a source to dust were investigated using microchambers in a thermostatic incubator: (1) mass transfer through direct contact with source surfaces; (2) mass transfer through air. A 20-day emission experiment with settled dust was performed at 30 °C. Significantly higher concentrations were observed in dust that was in direct contact than in dust that was not, which indicated that direct contact enhanced the sorption of the dust on DNOP. The difference between source and non-source surface was low of the migration of the DNOP in the dust. In addition, the temperature and dust loading and diffusion distance were considered. The results suggested that the temperature did not considerably influence the difference between source and non-source surface; however, the difference increased with an increase in dust loading. These results can help understand the mass transfer mechanism of PAEs to implement effective control measures and reduce the human exposure to PAEs in indoor environments. [Display omitted] • Direct contact played an important role in migration of DNOP from source to dust. • Contribution of direct contact of the migration was not extremely high. • Migration via air in the boundary level should not be neglected. • Temperature has little influence on the difference between source and non-source surface. Dust loading had a positive correlation with the difference between source and non-source surface. [ABSTRACT FROM AUTHOR]

Indoor semivolatile organic compounds (SVOCs), present in the air, airborne particles, settled dust, and other indoor surfaces, can enter the human body through several pathways. Knowing the partitioning between gaseous and particulate phases is important in identifying specific pathway contributions and thereby accurately assessing human exposure. Numerous studies have developed equilibrium equations to predict airborne particle/gas (P/G) partitioning in air ( K ) and dust/gas (D/G) partitioning in settled dust ( P ). The assumption that P/G and D/G equilibria are instantaneous for airborne and settled dust phases, commonly adopted by current indoor fate models, is not likely valid for compounds with high octanol-air partition coefficients ( K D ). The assumption that P/G and D/G equilibria are instantaneous for airborne and settled dust phases, commonly adopted by current indoor fate models, is not likely valid for compounds with high octanol-air partition coefficients ( K OA ). Here, we develop steady-state based equations to predict K P and K D in the indoor environment. Results show that these equations perform well and are verified by worldwide monitoring data. It is suggested that instantaneous steady state could work for P/G and D/G partitioning of SVOCs in indoor environments, and the equilibrium is just a special case of the steady state when log K OA < 11.38 for P/G partitioning and log K OA < 10.38 for D/G partitioning. These newly developed equations and methods provide a tool for more accurate assessment for human exposure to SVOCs in the indoor environment.

Settled dust is an important medium for semivolatile organic compound (SVOC) transport indoors. Understanding the mechanism of interaction between SVOCs and settled dust can greatly improve the exposure assessment. This study develops an analytical model to elucidate the mechanism of direct contact between SVOC sources and settled dust. The model incorporates the adsorption of SVOCs onto indoor surfaces, which was ignored in previous numerical models. Based on this model, a hybrid optimization method is applied to determine the key parameters of SVOC transport, i.e., the diffusion coefficient in the dust, the dust-air partition coefficient, and the chamber surface-air partition coefficient. Experiments of direct contact between SVOC source materials containing organophosphorus flame retardants (OPFRs) and settled dust were conducted in chambers. The key parameters were determined by performing curve fitting using data collected from the OPFR chamber tests and from the literature on phthalates. The reliability and robustness of the model and measurement method are demonstrated by the high fitting accuracy and sensitivity analysis. The obtained key parameters are more accurate than those from correlations in prior studies. Further analysis indicates that dust-air partition coefficient plays an important role and the adsorption effect on surfaces cannot be neglected for SVOC transport.

Abstract: For researches on toxic chemicals in settled indoor dust, selection of dust fraction is a critical influencing factor to the accuracy of human exposure risk assessment results. However, analysis of the selection of dust fraction in recent studies revealed that there is no consensus. This study classified and presented researches on distribution of toxic chemicals according to dust particle size and on relationship between dust particle size and human exposure possibility. According to the literature, beyond the fact that there were no consistent conclusions on particle size distribution of adherent fraction, dust with particle size less than 100μm should be paid more attention and that larger than 250μm is neither adherent nor proper for human exposure risk assessment. Calculation results based on literature data show that with different selections of dust fractions, analytical results of toxic chemicals would vary up to 10-fold, which means that selecting dust fractions arbitrarily will lead to large errors in risk assessment of human exposure to toxic chemicals in settled dust. Taking into account the influence of dust particle size on risk assessment of human exposure to toxic chemicals, a new methodology for risk assessment of human exposure to toxic chemicals in settled indoor dust is proposed and human exposure parameter systems to settled indoor dust are advised to be established at national and regional scales all over the world. [Copyright &y& Elsevier]

Indoor microbial exposure has been related to allergy and respiratory disorders. However, the lack of standardized sampling methodology is problematic when investigating dose-response relationships between exposure and health effects. In this study, different sampling methods were compared regarding their assessment of microbial exposures, including culturable fungi and bacteria, endotoxin, as well as the total inflammatory potential (TIP) of dust samples from Danish homes. The Gesamtstaubprobenahme (GSP) filter sampler and BioSampler were used for sampling of airborne dust, whereas the dust fall collector (DFC), the electrostatic dust fall collector (EDC), and vacuum cleaner were used for sampling of settled dust. The GSP assessed significantly higher microbial levels than the BioSampler, yet measurements from both samplers correlated significantly. Considerably higher levels of fungi, endotoxin, and TIP were found in the EDC compared with the DFC, and regarding fungi, the EDC correlated more strongly and significantly with vacuumed dust than the DFC. Fungi in EDC and vacuum dust correlated most strongly with airborne dust, and in particular, the measurements from the EDC associated well with those from GSP. Settled dust from the EDC was most representative of airborne dust and may thus be considered as a surrogate for the assessment of indoor airborne microbial exposure. Practical Implications Significant discrepancies between sampling methods regarding indoor microbial exposures have been revealed. This study thus facilitates comparison between methods and may therefore be used as a frame of reference when studying the literature or when conducting further studies on indoor microbial exposure. Results also imply that the relatively simple EDC method for the collection of settled dust may be used as an alternative to otherwise tedious and time-consuming airborne dust sampling. [ABSTRACT FROM AUTHOR]

Der p 1 is the main allergen of house dust mite Dermatophagoides pteronyssinus, which has routinely been detected in residential dust. However, the procedure for extracting Der p 1 from reservoir dust has not been well defined. The aim of this study was to compare Der p 1 mass fractions in dust extracts prepared using the following extraction buffers: phosphate (pH 7.4), borate (pH 8.0), and ammonium bicarbonate (pH 8.0), all with 0.05 % Tween 20. Twenty-eight dust samples were divided into three aliquots and each portion was extracted with one of the three buffers at room temperature. Der p 1 mass fractions were measured in a total of 84 dust extracts using the enzyme immunoassay (range: 0.1 µg g-1 to 7.53 µg g-1). Statistical methods including intraclass correlation showed a high agreement between Der p 1 mass fractions irrespective of the extracting medium. Our results suggest that all three buffers are suitable for the extraction of mite allergens and routine Der p 1 analysis in dust. [ABSTRACT FROM AUTHOR]

The object of our study was to estimate Pb content in the legally-protected plant Hacquetia epipactis, as well as stinging nettle (Urtica dioica), in the nature reserves laid in the border zone between Poland and the Czech Republic. The following forms of Pb reserves in soil were determined for biotopes of these plants: pseudo-total content and speciation forms, as well as soluble and insoluble forms in dust settled on leaves. Migration of Pb was analyzed from forms directly bioavailable (exchangeable and adsorbed) and indirectly bioavailable (organically bound and carbonates) in soil in the soil-rhizome system. We also assessed the migration of Pb in settled dust system -- leaves. Research shows that H. epipactis has the ability to accumulate Pb in the form of exchangeable and adsorbed Pb from the soil and soluble forms Pb in settled dust on the leaves. [ABSTRACT FROM AUTHOR]

Abstract: The aims of this work were to quantitatively and qualitatively study culturable fungi and bacteria in the air and settled dust in the storerooms of five Polish libraries and archives as well as to estimate the effect of water intrusion on the microbial air quality indoors. In all studied storerooms, the total bioaerosol concentrations at the workplaces ranged from 100 to 1000 cfu/m3. The most prevalent part of the storerooms’ bioaerosol consisted of bacteria, mainly Staphylococcus spp. and Micrococcus spp., followed by filamentous fungi. In four of the studied premises, fungal aerosol concentrations were below 100 cfu/m3. The only exception was observed in the fifth storeroom, which has been periodically flooded with rainwater and where significantly higher concentrations of fungal aerosol were measured. Among the identified fungal species, those of the genus Penicillium were the most numerous. Moreover, Trichothecium laxicephalum and Alternaria tenuis were present in all of the examined storerooms. The other objective of this study was to evaluate the effect of renovation and mechanical cleaning of the flooded storeroom collection on the level of microbial contamination. The obtained results show that both of the applied procedures reduced the concentration of fungal and bacterial aerosols by almost 80% and 50%, respectively. A significant reduction in the number of airborne microbial species was also noted. Hence, if the source of moisture is removed and mechanical cleaning is subsequently applied, the hygienic quality of a storeroom collection can be significantly improved. [Copyright &y& Elsevier]

Abstract: Few studies have assessed in home factors which contribute to airborne endotoxin concentrations. In 85 inner city Baltimore homes, we found no significant correlation between settled dust and airborne endotoxin concentrations. Certain household activities and characteristics, including frequency of dusting, air conditioner use and type of flooring, explained 36–42% of the variability of airborne concentrations. Measurements of both airborne and settled dust endotoxin concentrations may be needed to fully characterize domestic exposure in epidemiologic investigations. [Copyright &y& Elsevier]

Abstract: HVAC filters are in place for extended periods of time and can serve as integrated air samplers. This paper presents a comparison of bacterial and fungal concentrations and communities in HVAC filter dust and other sampling locations in occupied residences and in the unoccupied UTest House. A DNA-based, culture-independent approach was utilized to characterize the microbial communities. Microbial concentrations and communities in HVAC filter dust samples were not statistically different from those in high surface dust samples in occupied homes. Despite the general similarity in the communities, Proteobacteria were present in greater proportion in HVAC filter dust samples than in surface dust samples suggesting the air origin of this phylum. Gram-positive bacteria were present in greater proportion in occupied residences than in an unoccupied test house, confirming the potential association of this group with occupants. HVAC filter microbial communities were not different from those present in a composited month-long indoor air sample providing preliminary evidence that filters could be a viable option for long-term investigation of airborne biological contaminants. [ABSTRACT FROM AUTHOR]

Abstract: As part of the Danish Indoor Environment and Children’s Health (IECH) study, dust samples were collected from 500 bedrooms and 151 daycare centers of children (ages 3 to 5) living on the island of Fyn. The present paper reports results from the analyses of these samples for five phthalate esters (diethyl phthalate (DEP), di(n-butyl) phthalate (DnBP), di(isobutyl) phthalate (DiBP), butyl benzyl phthalate (BBzP), di(2-ethylhexyl) phthalate (DEHP)) and three PAHs (pyrene, benz[a]anthracene (B[a]A) and benzo[a]pyrene (B[a]P)). The three PAHs and DEHP were detected in dust samples from all sites, while DEP, DnBP, DiBP and BBzP were detected in more than 75% of the bedrooms and more than 90% of the daycare centers. The dust mass-fractions of both phthalates and PAHs were log-normally distributed. With the exception of DEP, the mass-fractions of phthalates in dust were higher in daycare centers than homes; PAH mass-fractions in dust were similar in the two locations. There was no correlation among the different phthalates in either homes or daycare centers. In contrast, the PAH were correlated with one another – more strongly so in homes (R 2 =0.80–0.90) than in daycare centers (R 2 =0.28–0.45). The dust levels of several phthalates (BBzP, DnBP and DEHP) were substantially lower than those measured in a comparable study conducted 6–7 years earlier in Sweden. Although usage patterns in Denmark differ from those in Sweden, the current results may also reflect a change in the plasticizers that are used in common products including toys. PAH levels were roughly an order of magnitude lower than those measured in Berlin and Cape Cod residences, suggesting that the Danish sites are less impacted by motor vehicle emissions. [Copyright &y& Elsevier]

Biodeterioration of heritage collections caused by microorganisms is a worldwide problem. To avoid degradation caused by biological contaminants transported into the indoor environment by air, proper bioaerosol protection is required. The aim of this study was to assess the level of microbial contamination of the Auschwitz-Birkenau Museum collection based on qualitative and quantitative analyses of bacteria and fungi isolated from the atmosphere and settled dust of museum storerooms. The obtained results demonstrated that a correctly operated air-conditioning system and limiting the number of visitors in the studied storerooms can significantly inhibit microbial contamination of the air and decrease deposition of bacterial and fungal particulates on exhibit surfaces. The performed analyses confirm that an aerobiological assessment of museum premises is a useful tool in their hygienic evaluation and, if necessary, in decision-making regarding interventions to minimize biological decay of collections. [ABSTRACT FROM AUTHOR]

The work demonstrated the migration of Cr, Ni, Co, Cd, Pb, Cu, Zn, Mn, Fe present in sites of common coltsfoot, common yarrow, stinging nettle growing within the scope of the direct influence of Lagisza Power Station (Suesia, Poland). The superior objective of the research was to determine the accumulation of metals in particular parts of medical plants (roots, leaves, stems, flowers) with reference to the bio-available resources of the investigated metals present in soil and the settled dust on the surface of leaves, as exemplified by sites at variable distances from the punctual emitter. The study included a speciation analysis of the investigated metals in soil according to Rudd, in the four geographical directions (N, S, E, W), in the function of distance from the power station: 50 m, 500 m, 1000 m, 3000 m, 5000 m. By means of this method the research determined the bio-availability of metals from soil to plants. The content of metals in soil and particular morphological parts of plants and in the settled dust (the soluble fraction) was measured by means of the atomic absorption spectrometry method (AAS). The ecotoxicologic characteristic was defined for the chosen species of plants. An increase in the content of the chosen metals in the function of distance in particular species of plants was observed, as a result of the immission of thick particles of dust in the vicinity of the power station. The accumulation of particular metals was also determined by the plant species. [ABSTRACT FROM AUTHOR]

The occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) in a city of Central China were determined in the settled dust and its extracted water phase from different land use types and bus stops in Nanchang City. The physicochemical properties of its water extracted dissolved organic matter (WEOM) were characterized to investigate the effect of fluorescence organic matter on the dust-water partitioning coefficients (K d) using three-dimensional excitation-emission matrix fluorescence spectroscopy combined parallel factor analysis. Results showed that the range of ∑PAHs in settled dust and the extracted water phase was 0.05–15.92 μg·g−1 and 2–211 ng·L−1, respectively. These PAHs mostly came from the combustion of biomass. The risk assessment showed that PAHs in dust had no obvious health risk (less than the magnitude of 10−6). Additionally, the high molecular weight (HMW) PAHs and the low molecular weight (LMW) PAHs were preferentially adsorbed by dust and the dissolved portion, respectively. It was confirmed by the relatively high log K d values of 4.23 for the HMW-PAHs. Pearson correlation analysis suggested that the higher concentration of dissolved organic carbon and humic-like substance were in favor of PAHs in dust released into waters. This study can provide information on pollution control when considering the impact of fluorescent organic matter on the fate and transport of PAHs. [Display omitted] • Partitioning behavior of PAHs between dust and WEOM was investigated. • Higher concentrations of ∑PAHs in both dust and WEOM were from the traffic roads. • LMW-PAHs preferred to dissolve in waters due to their higher solubility. • HMW-PAHs were predominantly existed in dust having a higher log K d value. • Humic-like substance was in favor of PAHs in dust released into waters. [ABSTRACT FROM AUTHOR]

During a repair and reconstruction project of an unpaved highway in a remote region of Alaska, workers discovered, after construction had commenced, that the materials used from a local material site contained asbestos (variously described as tremolite or actinolite). The regional geology indicated the presence of ultramafic rock, which often contains asbestos. Evaluation of asbestos exposure to workers, their equipment, and living quarters was required, as was the possible future exposure of workers and the general public to asbestos already used in the roadway construction. In addition, a decision was needed on whether to use materials from the contaminated site in the future. Of the almost 700 breathing zone air monitoring samples taken of the workers, 3% of the samples indicated exposures at or near 0.1 f/cc by the National Institute for Occupational Safety and Health (NIOSH) 7400 phase contrast microscopy (PCM) procedure. Thirty-six of the PCM samples underwent transmission electron microscopy (TEM) analysis by the NIOSH 7402 procedure, which indicated that about 40% of the fibers were asbestos. After classifying samples by tasks performed by workers, analysis indicated that workers, such as road grader operators who ground or spread materials, had the highest exposures. Also, monitoring results indicated motorist exposure to be much less than 0.1 f/cc. The design phase of any proposed construction project in regions that contain ultramafic rock must consider the possibility of amphibole contamination of roadway materials, and budget for exploration and asbestos analysis of likely materials sites. [ABSTRACT FROM AUTHOR]

A critical evaluation of human exposure to phthalate esters in indoor environments requires the determination of their distribution among the gas phase, airborne particles and settled dust. If sorption from the gas phase is the dominant mechanism whereby a given phthalate is associated with both airborne particles and settled dust, there should be a predictable relationship between its particle and dust concentrations. The present paper tests this for six phthalate esters (DMP, DEP, DnBP, DiBP, BBzP and DEHP) that have been measured in both the air and the settled dust of 30 Berlin apartments. The particle concentration, C Particle, of a given phthalate was calculated from its total airborne concentration and the concentration of airborne particles (PM4). This required knowledge of the particle–gas partition coefficient, K p, which was estimated from either the saturation vapor pressure (p s) or the octanol/air partition coefficient (K OA). For each phthalate in each apartment, the ratio of its particle concentration to its dust concentration (C Particle/C Dust) was calculated. The median values of this ratio were within an order of magnitude of one another for five of the phthalate esters despite the fact that their vapor pressures span four orders of magnitude. This indicates that measurements of phthalate ester concentrations in settled dust can provide an estimate of their concentration in airborne particles. When the latter information is coupled with measurements of airborne particle concentrations, the gas-phase concentrations of phthalates can also be estimated and, subsequently, the contribution of each of these compartments to indoor phthalate exposures. [Copyright &y& Elsevier]

In an effort to better understand the relationship between different fungal sampling methods in the indoor environment, four methods were used to quantify mold contamination in 13 homes with visible mold. Swab, fungal spore source strength tester (FSSST), and air samples (total of 52 samples) were analyzed using both the microscopic (total spore count) and culture-based (CFU count) enumeration techniques. Settled dust samples were analyzed for culturable fungi only, as the microscopic enumeration was restricted by the masking effect. The relationships between the data obtained with the different sampling methods were examined using correlation analysis. Significant relationships were observed between the data obtained from swab and FSSST samples both by the total counting (r = 0.822, p < 0.05) and by the CFU counting (r = 0.935, p < 0.01). No relationships were observed between air and FSSST samples or air and settled dust samples. Percentage culturability of spores for each sampling method was also calculated and found to vary greatly for all three methods (swab: 0.03% to 63%, FSSST: 0.1% to > 100%, air: 0.7% to 79%). These findings confirm that reliance on one sampling or enumeration method for characterization of an indoor mold source might not provide an accurate estimate of fungal contamination of a microenvironment. Furthermore, FSSST sampling appears to be an effective measurement of a mold source in the field, providing an upper bound estimate of potential mold spore release into the indoor air. Because of the small sample size of this study, however, further research is needed to better understand the observed relationships in this study. [ABSTRACT FROM AUTHOR]

Endotoxin, a characteristic external fraction of the outer membrane from Gram-negative bacteria, continuously shed into the environment, is considered as an important risk factor for human health. Our purpose was to study the bacterial species contaminating healthy working environments. Airborne, working surfaces and carpet dust samples were collected from 25 offices. Bacterial species were identified with biochemical ApiSystem® strips. Endotoxin concentrations in settled dust were measured with the kinetic chromogenic Limulus assay. The airborne bacterial level varied from 44-2,511, with a median of 277 cfu/m3. Bacterial contamination on surfaces ranged from 1–1000, with 33 cfu/25 cm2 as median value. On carpets, bacterial concentration ranged from 0.73–185 x 105 cfu/g, with 7.28 x 105 cfu/g as median value. Endotoxin concentration varied from 4.6-116.2 EU/mg, with a median of 20.3 EU/mg. Altogether, 501 bacterial strains were isolated. The species variability was greater in Gram-negative bacteria than in Gram-positive cocci with 41 versus 34 various species. In conclusion, people working in healthy offices can be exposed to large concentrations of airborne and dust bacteria and related endotoxin concentrations, giving a risk of work-related diseases. [ABSTRACT FROM AUTHOR]

Analysis of settled dust collected from carpeting and furnishings is occasionally used by investigators to determine whether an environment contains unusual fungi. Little information is available concerning the types and concentrations of culturable fungi present on textile surfaces in normal residential settings not affected by unusual mold reservoirs, such as from fungal growth sites within the built environment. This study presents the results of the collection and analysis of surface dust from 26 residential environments that were prescreened by interview, physical inspection, and air sampling to limit the surface dust collection to structures in which there was no history of water intrusion, flooding, plumbing leaks, signs of mold growth, or evidence of unusual airborne fungal spore types or concentrations. In those structures found to have no history or indications of water events or unusual fungi, surface dust was vacuumed from prescribed horizontal areas on carpet and textile-covered furnishings. These samples were then subjected to fungal culture, from which viable colonies were enumerated and identified. Based on the study results, it does not appear reasonable that the frequently quoted total fungi concentration exceeding 10 5 CFU/g is definitive evidence that a residential surface is contaminated with unusual amounts of culturable fungi. Collocated samples collected from eight side-by-side carpets sections revealed poor reproducibility. While settled dust sampling may be appropriate for determining the fungal status of a localized area, or as a gross screening tool, using settled dust results alone to establish the presence of unusual fungal types or concentrations within a structure appears to be inappropriate, and using settled dust results with other investigative methods, such as visual observations and air sampling, requires cautious interpretation. [ABSTRACT FROM AUTHOR]

Abstract: Phthalic acid esters and phosphororganic compounds (POC) are generally known as semivolatile organic compounds (SVOCs) and are frequently utilized as plasticizers and flame retardants in commercial products. In the indoor environment, both compound groups are released from a number of sources under normal living conditions and accumulate in air and dust. Therefore, inhalation of air and ingestion of house dust have to be considered as important pathways for the assessment of exposure in living habitats. Especially in the case of very young children, the oral and dermal uptake from house dust might be of relevance for risk assessment. A critical evaluation of indoor exposure to phthalates and POC requires the determination of the target compounds in indoor air and house dust as well as emission studies. The latter are usually carried out under controlled conditions in emission test chambers or cells. Furthermore, chamber testing enables the determination of condensable compounds by fogging sampling. In the case of automobiles, specific scenarios have been developed to study material emissions on a test stand or to evaluate the exposure of users while the vehicle is driving. In this review, results from several studies are summarized and compared for seven phthalic esters and eight POC. The available data for room air and dust differ widely depending on investigated compound and compartment. Room air studies mostly include only a limited number of measurements, which makes a statistical evaluation difficult. The situation is much better for house dust measurements. However, the composition of house dust is very inhomogeneous and the result is strongly dependent on the particle size distribution used for analysis. Results of emission studies are presented for building products, electronic equipment, and automobiles. Daily rates for inhalation and dust ingestion of phthalic esters and POC were calculated from 95-percentiles or maximum values. A comparison of the data with results from human biomonitoring studies reveals that only a small portion of intake takes place via the air and dust paths. [Copyright &y& Elsevier]

Twelve organophosphorus compounds (OPs), which are used for diverse purposes (e.g. as plasticizers and flame retardants), were analysed in settled house dust from 15 indoor environments and in wipe test samples from computer screens and covers. Seven of the substances analysed dominated Swedish imports of OPs in 1999, six of these are also listed as EU High Production Volume Chemicals. Eight of the substances were found in all samples. Tris(2-butoxyethyl)phosphate was the most abundant in most of the samples, with levels ranging from 0.014 to 5.3 g/kg followed by tris(2-chloroethyl)phosphate, tris(chloropropyl)phosphate and tris(1,3-dichloropropyl)phosphate. In wipe test samples from computers, triphenyl phosphate proved to be the main component of the OPs analysed (4.0 μg/m2). Potential sources of these compounds include, inter alia, floor polish, polyvinylchloride floor coverings, upholstery and plastic products. The distribution patterns of the OPs differed between the sites and generally reflected the building materials and consumer products used in their vicinity. [Copyright &y& Elsevier]

Settled dust has been collected inside the main foyers of three University buildings in Wolverhampton City Centre, U.K. Two of the three buildings are located in a street canyon used almost exclusively by heavy duty diesel vehicles. The dust was collected on adhesive carbon spectro-tabs to be in a form suitable for analysis by scanning electron microscope and energy dispersive X-ray analysis. Using these analytical techniques, individual particle analysis was undertaken for morphology and chemistry. Seasonal variations and variations due to location were observed in both the morphological measurements and chemical analysis. Many of the differences appear attributable to the influence of road traffic, in particular, the heavy duty diesel vehicles, travelling along the street canyon. [ABSTRACT FROM AUTHOR]

Phthalate esters (PAEs), as a group of typical semi-volatile organic compounds (SVOCs) with excellent performance as plasticizers, are widely used in indoor products and have been found to harm human health. There are two migration pathways for phthalates from the source to settled dust, namely: direct and non-direct contact with the sources. Therefore, concentrations of phthalates in settled dust have exhibited significant differences in the source and non-source surfaces in past literature. In this study, a porous media model is proposed to characterise the mass transfer mechanism of phthalates from the source into settled dust via two migration pathways. We compared the simulation data with the experimental data in the literature to validate the model, and the simulation results were consistent with the experimental results within an acceptable degree. Based on the model, a certain thickness of settled dust was selected to simulate the dust-phase concentration change of DEHP within 500 days and the concentration difference between source (value of 21,687.33 μg/g) and non-source surfaces (value of 150.32 μg/g) was compared. Then, the difference in the concentration distribution in the dust layer of different mass transfer pathways was visually demonstrated. Dust loading can dominate the mass transfer of phthalates and influence the concentration in dust by affecting the characteristics of the dust layer (porosity and thickness of settled dust). In addition, the solid diffusion coefficient and K oa values of phthalates have a significant influence on the dust-phase concentration and time to reach a steady state. • A porous media model was proposed to characterise PAEs transfer in the dust. • Difference of PAEs in the dust between direct and non-direct transfer was pictured. • Several parameters of dust had a significant effect on PAEs levels. [ABSTRACT FROM AUTHOR]

Concentrations and congener-specific profiles of total 209 polychlorinated biphenyls (PCBs) were investigated in settled dust samples collected from end-of-life vehicle (ELV) processing, urban, and rural areas in northern Vietnam. Concentrations of total 209 PCBs, seven indicator congeners, and twelve dioxin-like PCBs decreased in the order: ELV working > ELV living ≈ urban > rural dusts. Penta- and hexa-CBs dominated the homolog patterns in all the samples with higher proportions in the ELV dusts compared to the urban and rural house dusts. The abundance and pattern of PCBs in the ELV dusts suggest on-going emissions of these compounds related to processing of vehicular oils and lubricants containing PCBs, whereas the presence of PCBs in the urban and rural house dusts indicate long-time releases. However, levels of some PCBs identified as by-products of pigment manufacturing (e.g., PCB-11 and PCB-209) were higher in the urban house dusts than those from other locations, resulting from human activities utilizing paints and pigments. Daily intake doses (ID), non-carcinogenic hazard quotient (HQ), and lifetime cancer risk (CR) of PCBs through dust ingestion were estimated for ELV workers and residents in the studied areas. The workers and children in the ELV sites were estimated to be at higher risk of PCB exposure, however almost all of the HQ < 1 and CR < 10−4 indicate no serious risk related to dust-bound PCBs. Unlabelled Image • Informal end-of-life vehicle processing activities were potential PCB sources. • Σ209PCBs were higher in the ELV dusts than normal house dusts. • Concentrations of PCB-11 were higher in the urban house dusts. • ELV workers and children were at higher risk of exposure to dust-bound PCBs. [ABSTRACT FROM AUTHOR]