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Dust in the home environment is thought to be a potential trigger for increasing allergic diseases, such as allergic rash, rhinitis, asthma, and other conditions, associated with dust mites. To verify the status of dust mite prevalence in indoor surroundings, we collected 189 dust samples from the air conditioner filters (n = 75) and floors (n = 114) of households, schools, and hotels in the Anhui area, China. All samples were measured for dust mite breeding rate and breeding density under light microscopy and analyzed for dust mite species Dermatophagoides farinae 1 (Der f 1) and Dermatophagoides pteronyssinus 1 (Der p 1) allergen using enzyme-linked immunosorbent assay (ELISA). The dust mite breeding rates were 34.67% (26/75) and 20.18% (23/114), respectively, in the dust samples from the floor and air conditioning filters. The breeding density was the highest in households (10/g), followed by schools (9/g) and hotels (4/g). ELISA indicated that the allergen threshold (2.0 µg/g dust) of Der f 1 was exceeded in only two samples and Der p 1 in one sample. Additionally, a questionnaire was used to investigate the health knowledge on allergic diseases involved in indoor facilities, finding that most allergy sufferers were aware that indoor dust might be responsible for their conditions. The findings suggest that regular maintenance of indoor hygiene and cleaning of air-conditioning filters should reduce the risks of exposure to indoor allergens. [ABSTRACT FROM AUTHOR]

Human exposure to flame retardants occurs in microenvironments due to their ubiquitous presence in consumer products and building materials. Recent research suggests higher levels of exposure through elevated surface dust (ESD) compared to floor dust (FD). However, it is unclear whether this pattern is consistent in different microenvironments beyond the home. We hypothesized that time spent in various microenvironments will significantly modify the pattern of human exposure to flame retardant chemicals in ESD and FD. We tested this hypothesis by collecting time activity diaries from 43 participants; and by estimating human exposure to 10 polybrominated diphenyl ether and 8 non-polybrominated diphenyl ether flame retardant chemicals, based on chemical concentrations measured in different microenvironments visited by the participants. The results of paired t-tests show that, with some notable exceptions, estimates of human exposure to most chemicals through ESD are statistically significantly higher for ∑PBDE (p=0.00) and ∑non-PBDEs (p=0.00) than through FD. This study reinforces the need to integrate temporal, locational, and elevation dimensions in assessing human exposure to potentially toxic flame retardant chemicals.

Residual floor dust at an indoor firing range was investigated for the presence of selected heavy metals, and the associated health risks (non-carcinogenic and carcinogenic) were explored. Average heavy metal concentrations decreased in the following order: Pb >> Cu >> Zn > Mn > Cr > Ni > Cd. For the examined floor dust, moderate to significant degrees of enrichment were observed for Ni, Cd, Cr and Zn while extremely high degrees of enrichment were reported for Cu and Pb. Lead was the only heavy metal that exceeded the Hazard Index value of 1 and the potential carcinogenic risks for Cd and Ni were considered acceptable. A potential carcinogenic risk existed for Cr, as denoted by a total lifetime cancer risk value greater than 10-4. [ABSTRACT FROM AUTHOR]

MRCoNS (Methicillin-Resistant Coagulase-Negative Staphylococci) are a group of opportunistic pathogens that possess abilities to survive desiccated environments and resist many antimicrobial drugs. From floor dust collected within community and hospital buildings, 78 penicillin-resistant staphylococci were isolated and confirmed to be coagulase negative. Their antibiotic resistances were investigated according to CLSI guidelines and the presence of the mecA gene. We found 72 isolates (92.31%) classified as MDR (multidrug resistance), of which 9 isolates (11.54%) indicated resistance against 7 classes of antibiotics. Fifty-nine isolates (75.64%) were specified as MRCoNS; 8 isolates (10.26%) from the community, and 51 isolates (65.38%) from the hospital. All isolates survived a week of desiccation with only 2 log10CFU decrease, and were identified as S. warneri, S. arlettae, S. equorum, S. haemolyticus, S. saprophyticus, S. capitis, and S. cohnii. Among them, S. capitis was found only from the hospital, while S. cohnii was the most prevalent species recovered from both places. Nearly all of them possess characteristics of MDR or MRCoNS. With ability-to-survivedesiccation on floor dust, they could become a hidden threat as a crucial source of antibioticresistant genes, which is needed to be monitored to prevent the emergence of multidrug resistant staphylococci with high virulence potential. [ABSTRACT FROM AUTHOR]

Abstract Background Novel brominated flame retardants (NBFRs) have been increasingly used as alternatives to legacy BFRs (e.g., PBDEs and HBCDs) in consumer products, but are liable to emigrate and contaminate indoor dust. In this study, a total of 154 house dust samples including floor dust (FD) and elevated surface dust (ESD) were collected in the biggest metropolitan area (Shanghai) of East China in 2016. Limited information about temporal variation of NBFRs indoors is available, while the period of sampling is influential in human exposure estimates. Levels, temporal variation, and human exposure of seven target NBFRs such as decabromodiphenylethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EHTBB), and bis(2-ethylhexyl) tetrabromophthalate (BEHTEBP) were investigated in indoor house dust. Results Concentrations of ∑7NBFRs ranged from 19.11 to 3099 ng/g with a geomean of 295.1 ng/g in FD, and from 34.74 to 404.6 ng/g with a geomean of 117.9 ng/g in ESD. The geomeans of DBDPE were 219.6 ng/g in FD and 76.89 ng/g in ESD, accounting for 90.5% and 80.5% of ∑7NBFRs. Levels of EHTBB, BTBPE, and DBDPE in FD exceeded significantly those in ESD. The temporal variation in ∑7NBFRs in FD was ranked as summer > winter > autumn > spring. The daily exposure doses (DEDs) of ∑7NBFRs via dust ingestion decreased as: infants > toddlers > children > teenagers > adults. Infants showed the highest DED in FD, 9.1 ng/kg bw/day. Conclusions DBDPE clearly dominated the NBFRs in both FD and ESD, but the concentrations of DBDPE in this study were generally moderate compared with the other international studies. Dust ingestion was the major pathway of human exposure to NBFRs indoors. About eightfold difference in exposure estimates between infants and adults showed that infants faced elevated exposure risks in FD. This study highlighted the necessity to estimate human exposure of NBFRs for different age groups using FD and ESD, respectively.

This study aimed to develop a Korean version of the Environmental Relative Moldiness Index based on the specific distribution of fungal flora in Korea. A total of 126 dwellings were selected for mold sampling, and each was classified as, flooded, water leaks/condensation, or non-water-damaged. Dust on floors was sampled using a vacuum cleaner with a Dustream collector and analysed by quantitative polymerase chain reaction for 36 types of molds included in the Environmental Relative Moldiness Index. The Environmental Relative Moldiness Index value was found to be 19.6 (-6.9-58.8) for flooded houses, 7.5 (-29.2-48.3) for water-damaged houses with leaks/condensation, and 0.8 (-29.2-37.9) for non-damaged dwellings. Significant differences were observed between flooded and non-water damaged dwellings (p<0.001) and between water-damaged and non-water damaged dwellings (p=0.032). The Korean Environmental Relative Moldiness Index consisted of 16 fungal species, which are very similar to those normally found in the Environmental Relative Moldiness Index in Korea (p=0.834). These findings indicate that Environmental Relative Moldiness Index values attributed to dust samples in Korea could be utilized for identification of flooded or water-damaged buildings. The Korean Environmental Relative Moldiness Index could also be a promising tool for inexpensive assessment of long-term fungal exposure in Korean dwellings. [ABSTRACT FROM AUTHOR]

Environmental exposure to endotoxin, Fel d I (cat) allergen and Der p I (house dust mite) allergen have been associated with asthma symptoms and have been measured in the environment using various sampling methods, including the electrostatic dust collector. The objectives of this study were to investigate whether levels of endotoxin and allergens were detectable in electrostatic dust collectors and to examine the correlation of allergen and endotoxin levels between electrostatic dust collectors and vacuum sampling methods (floor dust and mattress dust). Electrostatic cloths, bedroom floor dust and mattress dust samples from a subset of 60 homes were randomly selected from the Health of Occupants of Mouldy Homes study for allergen and endotoxin analysis. Fel d I and Der p I allergens were analyzed by double monoclonal antibody ELISA and endotoxin by the kinetic Limulus amoebocyte lysate assay. An enhanced ELISA method was used to analyze Der p I in the electrostatic cloths. Endotoxin was detected in all samples, however Fel d I and Der p I were not detected in all electrostatic dust collector samples (detection in 53% and 15% of cloths respectively). No correlations were found between cloth and dust samples for endotoxin or Der p I, but moderate-to-strong correlations were found between all three sampling methods for Fel d I (rs = 0.612-0.715, p < 0.001). Poor correlation was found between floor dust and mattress dust samples for Der p I (rs = 0.256, p = 0.048). Electrostatic dust collectors may provide a way to measure airborne dust and allergen. Given the moderate-to-low correlations with vacuum dust sampling, this may present a unique measurement system which, when collected alongside traditional vacuum dust sampling, could provide additional exposure measures. Further studies are required to correlate endotoxin and allergen levels measured by electrostatic dust collector with air sampling and to explore the relationships between these bioaerosols, environmental factors and asthma. [ABSTRACT FROM AUTHOR]

Concentrations of polybrominated diphenyl ethers (PBDEs) and selected novel brominated flame retardants (NBFRs) were measured in indoor dust from the living areas of 18 homes in Basrah, Iraq. This is the first report of contamination of the Iraqi environment with these chemicals. To evaluate the implications for human exposure, samples were collected from both the floor and from elevated surfaces like tables, shelves and chairs. When normalised for the organic carbon content of the dust sample, concentrations in elevated surface dust of BDE-99, BDE-209, pentabromoethylbenzene (PBEB), bis (2-ethylhexyl) 3,4,5,6-tetrabromophthalate (BEH-TEBP), and decabromodiphenylethane (DBDPE) exceeded significantly (p

This study was undertaken to investigate levels of organophosphorus flame retardants (PFRs) and phthalates in floor and road dust from a manual e-waste dismantling facility and nearby communities in Thailand. Concentrations of Σ10 PFRs and Σ6 phthalates in floor dust from the facility were approximately 36–1,700 and 86,000–790,000 ng g−1, whereas those from the communities were about 13–9,200 and 44,000–2,700,000 ng g−1, respectively. The highest content of Σ10 PFRs (9,200 ng g−1) and Σ6 phthalates (2,700,000 ng g−1) in indoor dust was both detected in the dust sampled from a house with no prevailing winds located 350 m northeast of the facility. Levels of Σ10 PFRs and Σ6 phthalates in road dust from the facility were around 1,100–2,100 and 40,000–670,000 ng g−1, while those from the residences were about 650–2,000 and 27,000–650,000 ng g−1, respectively. Concentrations of Σ10 PFRs (2,100 ng g−1) and Σ6 phthalates (670,000 ng g−1) in road dust were greatest in the dust collected from the facility. For the distributional pattern, TBEP (tris (2-butoxyethyl) phosphate) was the main PFR in residential dust, whereas TPP (triphenyl phosphate) was the major PFR in facility dust. TBEP was also found to be the most prominent PFR in all road dust samples. Furthermore, DEHP (di-2-ethylhexyl phthalate) was the most abundant phthalate congener in both floor and road dust samples. Under realistic high-end scenarios of environmental exposure to DEHP, Thai toddlers (25.29 µg kg−1bw day−1) in the adjacent communities were exposed above the US EPA's (United States Environmental Protection Agency) reference dose (RfD) for this congener (20 µg kg−1bw day−1). Our data reveal that the PFR and phthalate-containing products at the residences are a likely substantial source of PFRs and phthalates to the surrounding indoor environment, and humans can be exposed to PFRs and phthalates in their dwellings via the settled floor dust. [ABSTRACT FROM AUTHOR]

Human exposure to flame retardants occurs in microenvironments due to their ubiquitous presence in consumer products and building materials. Recent research suggests higher levels of exposure through elevated surface dust (ESD) compared to floor dust (FD). However, it is unclear whether this pattern is consistent in different microenvironments beyond the home. We hypothesized that time spent in various microenvironments will significantly modify the pattern of human exposure to flame retardant chemicals in ESD and FD. We tested this hypothesis by collecting time activity diaries from 43 participants; and by estimating human exposure to 10 polybrominated diphenyl ether and 8 non-polybrominated diphenyl ether flame retardant chemicals, based on chemical concentrations measured in different microenvironments visited by the participants. The results of paired t -tests show that, with some notable exceptions, estimates of human exposure to most chemicals through ESD are statistically significantly higher for ∑ PBDE ( p = 0.00) and ∑ non-PBDEs ( p = 0.00) than through FD. This study reinforces the need to integrate temporal, locational, and elevation dimensions in assessing human exposure to potentially toxic flame retardant chemicals. [ABSTRACT FROM AUTHOR]

This study characterizes concentrations of polybrominated diphenyl ethers (PBDEs) in floor and road dust from a manual e-waste dismantling facility and adjacent communities in Thailand. Levels of Σ22 PBDEs in floor dust from the facility varied between 1,200 and 43,000 ng g−1, whereas those from adjacent communities were in the range 6.6-2,200 ng g−1. Concentrations of Σ22 PBDEs (43,000 ng g−1) were highest in floor dust collected from the facility. Levels of Σ22 PBDEs and all congeners studied, except for BDE-66, BDE-71, BDE-85, BDE-119, BDE-138, BDE-190 and BDE-191 in facility dust were significantly greater than those in residential dust (P= <0.001-0.017). Moreover, PBDE contents decreased with increasing distance from the facility, revealing that the facility may represent a principal source of PBDEs to the surrounding environment. Levels of Σ22 PBDEs in road dust from the facility varied from 27 to 21,000 ng g−1, while those from the adjacent residences were about 5.4-63 ng g−1. Concentrations of Σ22 PBDEs (21,000 ng g−1) were highest in road dust taken at the facility. The PBDE congener profile for floor dust from the facility was dominated by BDEs 28, 47 and 209, whereas domestic floor dust was predominated by BDEs 206 and 209. Under various scenarios of occupational and environmental exposure to BDE-99 and BDE-209, workers in the facility as well as adults and children in the adjacent communities were exposed below the United States Environmental Protection Agency (US EPA)'s reference doses (RfDs) for BDE-99 (100 ng/kg bw/day) and BDE-209 (7,000 ng/kg bw/day). [ABSTRACT FROM AUTHOR]

OBJECTIVE: To test the hypothesis that the association between levels of mould in floor dust and prevalence of potentially building-related symptoms may depend on the type of ventilation. METHODS: This stratified cross-sectional study is part of the Danish moulds in buildings program (DAMIB), including 503 adolescent schoolboys aged 13–17 years at 15 schools. Besides assessing symptom prevalences in questionnaires, we measured numerous potential risk factors in the school buildings. RESULTS: Stratifying on type of ventilation (natural, exhaust only, or full mechanical ventilation system), the negative effect of high levels of mould in floor dust was more pronounced in rooms with mechanical ventilation system. With a variable combining high level of moulds in floor dust with type of ventilation in the classroom, a significantly increased risk was found for all symptoms in the mechanically ventilated classrooms with high mould concentrations. In multiple logistic regression models, significant odds ratios (OR) ranged from 3.9 [95% confidence interval (95% CI) 1.5–10.1] (nasal congestion) to 17.0 (95% CI 2.1–138) (dizziness). CONCLUSIONS: The combined effect of moulds in dust and ventilation form might be a result of the higher air flow keeping the dust in the breathing zone for a longer time, thereby increasing the exposure for the occupants of the classrooms. It is important in future indoor air research also to focus on the combination effects of risk factors, including the type of ventilation.

This study investigates the particle size distribution of eight polybrominated diphenyl ethers (PBDEs) and five “novel” brominated flame retardants (NBFRs) in settled house dust. Elevated surface dust (ESD) and floor dust (FD) were collected from 5 homes in Birmingham, UK, yielding a total of 10 samples. Each sample was fractionated into three different particle sizes: 125–250 μm (P1), 63–125 μm (P2) and 25–63 μm (P3). Non-fractionated bulk dust samples (BD) were also analysed. BDE-209 predominated, comprising an average 74.3%, 77.3%, 69.2%, and 62.7% ΣBFRs of BD, P1, P2 and P3 respectively. Σ 5 NBFRs contributed 24.2%, 21.5%, 29.0% and 35.3% ΣBFRs, while Σ 7 tri-hepta-BDEs represented 1.5%, 1.2%, 1.7%, and 2.0% ΣBFRs. BEH-TEBP was the predominant NBFR contributing 76.9%, 75.1%, 83.1%, and 83.9% ΣNBFRs in BD, P1, P2 and P3 respectively; followed by DBDPE which contributed 20.1%, 21.9%, 14.1% and 13.9% ΣNBFRs. EH-TBB, BTBPE and PBEB were the least abundant NBFRs. Concentrations of Σ 7 tri-hepta-BDEs and BEH-TEBP in P3 exceeded significantly (P < 0.05) those in P2, with those in P2 exceeding significantly those in P1. In contrast, no significant differences were found between concentrations of BDE-209, EH-TBB, BTBPE, and DBDPE in different particle size fractions. Concentrations of Σ 7 tri-hepta-BDEs, BDE-209, and BEH-TEBP in ESD exceeded significantly those in FD (P < 0.05). Normalising BFR concentrations to organic carbon content, did not alter these findings. This suggests that differences in BFR concentrations between different particle size fractions are caused by variations in particle surface area to volume ratio, rather than by variations in organic carbon content. [ABSTRACT FROM AUTHOR]

This study aimed to compare and assess phthalate contamination in various indoor environments. In this study, 44 floor dust samples from different indoor environments in Delaware, USA were collected and analyzed for 14 phthalates using gas chromatography-mass spectrometry. Phthalates were detected in all dust samples with the total concentration ranging from 84 to 7117 mg kg−1. DEHP (di-2-ethylhexyl phthalate), BzBP (benzylbutyl phthalate), DBP (dibutyl phthalate), and DiBP (di-isobutyl phthalate) were both the most frequently and abundantly detected phthalates. The average concentration of total phthalates in dust from offices, student dorms, gyms, stores, and daycare centers was found to be significantly or insignificantly (P= 0.05) higher than that in dust from houses and apartments. Plastic flooring materials and the application of floor care chemical products were positively associated with total phthalate concentration in floor dust. Toxicological risk assessment indicated that an investigated daycare center in this study was the only indoor environment that may cause the intake amount of DEHP of infants, toddlers, and children via dust ingestion to exceed the reference dose established by the U.S. Environmental Protection Agency (USEPA). Regular monitoring on phthalate contamination in sensitive indoor environments is recommended. [ABSTRACT FROM AUTHOR]

Highlights: [•] Catalytic and chemical processes contributed to the ozone consumption at steady state. [•] Aldehydes were major reaction products from the ozonolysis of SVOCs in dust. [•] A bell shaped curve described the dependency of relative humidity on the reaction rate. [Copyright &y& Elsevier]

Abstract: The demand for phosphorus flame retardants (PFRs) has recently increased as an alternative to polybrominated diphenyl ether (PBDE). PFRs have been detected in house dust, but little is known about the concentrations of PFRs in private homes and the effects on human health. We measured the levels of 10 PFRs in indoor floor dust and upper surface dust from 128 Japanese dwellings of families with children in elementary school. The median (min–max) concentrations (μg/g) of PFRs were as follows: tris(2-butoxyethyl) phosphate (TBOEP), 30.88 (<0.61–936.65); tris(2-chloro-iso-propyl) phosphate (TCIPP), 0.74 (<0.56–392.52); and triphenyl phosphate (TPHP), 0.87 (<0.80–23.35). These values exceeded 50% detection rates, and the rates are median over the LOD in floor dust. The concentrations (μg/g) of TBOEP 26.55 (<0.61–1933.24), TCIPP 2.23 (<0.56–621.23), TPHP 3.13 (<0.80–27.47), tris(2-chloroethyl) phosphate (TCEP) 1.17 (<0.65–92.22), and tributyl phosphate (TNBP) 0.74 (<0.36–60.64) exceeded 50% detection rates in the upper surface dust. A significant positive correlation (P<0.05) between the concentrations of TCIPP and TBOEP was shown in floor dust and upper surface dust (n=48). Estimated median and 95th percentile daily intake was calculated for toddlers and elementary school children and was compared with reference dose values (RfD) from the literature. For TBOEP, the estimated 95th percentile intake from floor dust was 14% of RfD for toddlers and 4% for school children. The estimated intake from upper surface dust was somewhat lower. Estimated median intake of TBOEP and median intake for the other PFRs were less than 1% of the RfD. TBOEP, TCIPP and TPHP were the main PFRs in the dust. The median levels of PFRs are well below the RfD values. [Copyright &y& Elsevier]

Polybrominated diphenyl ethers (PBDEs) are considered harmful to human health because of their toxicities and persistence in environments. In the current study, the distribution and fate of PBDEs in classrooms and computer rooms in 17 elementary schools in South Korea have been described. Eight congeners (brominated diphenyl ether-28, -47, -99, -100, -153, -154, -183, and -209) in air, floor dust, and product surface dust were measured. While ∑8PBDEs in the air in classrooms showed considerable variations (0.659–1600 pg/m3, arithmetic mean ± s.d.: 377 ± 441 pg/m3), those in computer rooms were somewhat similar (134–220 pg/m3, arithmetic mean ± s.d.: 169 ± 40 pg/m3). ∑8PBDEs in floor dust varied over a wide range, from 453 to 45,700 ng/g, for all rooms. Based on congener patterns, two groups were created – CL-1 that is dominated by high-brominated congeners and CL-2 primarily comprising low-brominated congeners – for both air and floor dust of classrooms. Surface dust had low concentrations, ranged from ND to 181, from ND to 128, and from ND to 256 pg/cm2 for desk/chair sets, lockers, and playing tools, respectively. Pearson correlation coefficients were calculated individually for air, floor dust, and surface dust. The results indicate that both surface dust and floor dust may act as a secondary source of PBDEs in indoor environments after emission from facilities. Practical Implications Children have been estimated to have a higher potential exposure to PBDEs than adults. Since children spend most of their day time at school, PBDE distributions in school environments should be a matter of great concern. [ABSTRACT FROM AUTHOR]

This work introduces a spatially resolved quantitative model, based on conservation of mass and first order transfer kinetics, for following the transport and redistribution of outdoor soil to, and within, the indoor environment by track-in on footwear. Implementations of the DIRT model examined the influence of room size, rug area and location, shoe size, and mass transfer coefficients for smooth and carpeted floor surfaces using the ratio of mass loading on carpeted to smooth floor surfaces as a performance metric. Results showed that in the limit for large numbers of random steps the dual aspects of deposition to and track-off from the carpets govern this ratio. Using recently obtained experimental measurements, historic transport and distribution parameters, cleaning efficiencies for the different floor surfaces, and indoor dust deposition rates to provide model boundary conditions, DIRT predicts realistic floor surface loadings. The spatio-temporal variability in model predictions agrees with field observations and suggests that floor surface dust loadings are constantly in flux; steady state distributions are hardly, if ever, achieved. [ABSTRACT FROM AUTHOR]

In this stratified cross-sectional study in eight‘wet’ and seven‘dry’ schools, 1024 adolescent school children reported potentially building-related symptoms (BRS) in self-administrated questionnaires. From their classrooms dust samples were collected from floors, ventilation ducts, and air; settled dust was collected in cardboard boxes over a period of 5 months. Measurements of temperature, relative humidity and CO2 were performed. BRS were strongly associated with personal factors like recent airway infections, hay fever, asthma and psycho-social work load, but also to molds in floor dust and presence of mechanical ventilation. The association between molds in floor dust and BRS has in stratified analyses shown a strong association among adolescent school boys, and no association among adolescent school girls using multivariable analyses controlling for relevant confounders. In contrast to the menstruating school girls, the symptoms among the small group of not yet menstruating girls were associated with the levels of molds in floor dust. Their symptom prevalences were very similar to those of the boys. This finding makes us suggest a new hypothesis: The higher endogenous estrogen levels of sexually matured adolescent females seems to protect them from the effects of molds in dust, despite their overall higher symptom prevalence. In this cross-sectional epidemiological study of adolescent school children we found independent significant positive associations betweenbuilding-related symptomsand viable molds in floor dust in boys and non-menstruating girls. In contrast, no such associations were seen among menstruating girls. The identification of these two susceptible groups adds further support the relevance of minimizing sources of dust and mold exposure. [ABSTRACT FROM AUTHOR]

A newly developed dustfall device that collects airborne dust by sedimentation has been evaluated in Danish schools. Dust collected over 140 days was compared with airborne dust sampled during single school days and settled floor dust sampled at the end of a school day. Measurements of culturable fungi in air samples corresponded well to those from the dustfall collector in mechanically but not naturally ventilated rooms. Levels ofβ(1→3)glucan and culturable fungi in dust from the dustfall collector and settled floor dust did not agree well. Up to 10 times moreβ(1→3)glucan per milligram dust was found in the dustfall collectors than in settled floor dust. Only in dust from the dustfall collector was the mass concentration of culturable fungi (cfu/mg) significantly correlated with the degree of dampness. The culturability of fungi in the 140-day dustfall samples tended to be lower than in other types of samples. Nonetheless, the results indicated that the dustfall collector can be used to estimate the median concentration of airborne culturable fungi, provided identical sampling periods are used for all samples. The collector is cost effective and simple to use. Traditional ways of assessing exposure to microorganisms by sampling airborne dust or dust from floors have several disadvantages. In the present paper, a new sampler, the dustfall collector, which collects airborne dust by sedimentation over a period of months, is introduced. Tests of this collector indicate that it can be used to estimate the mean concentration of airborne culturable fungi but notβ(1→3)glucan over a long period and that the method can differentiate between buildings with different levels of water damage. [ABSTRACT FROM AUTHOR]

Studies investigating the effect of exposure to indoor allergens and endotoxin on human respiratory health usually take dust samples only at one single point of time and consider them to be representative for the indoor biocontaminant burden during a time period of several years. This singly measured biocontaminant concentration is related to adverse respiratory outcomes such as asthma, wheeze or others. We analysed two repeated measurements of mite and cat allergens in mattress and living room floor dust as well as endotoxin concentrations in living room floor dust. The repeated samples were taken over a time period of about 6 years. We investigated the repeatability over time of their concentrations by determining correlation coefficients and computing within- and between-home variance components. Our analysis was based on the population of a study on Indoor Factors and Genetics in Asthma (INGA) being carried out in 1995/96 and followed up in 2000/01. Complete data were available from 152 participants. The measured allergen concentrations were low and a considerable percentage of the values was below the limit of detection. The crude Spearman's rank correlation coefficients between the two measurements taken in 1995/96 and 2000/01 ranged from 0.32 to 0.61 for the dust mites allergens, from 0.21 to 0.44 for cat allergen and from 0.35 to 0.51 for endotoxin. Correlations were higher if measurements were performed on the same floor or the same mattress at both sampling time-points. The within-home variance for all measured biocontaminant concentrations was of about the same order as the between-home variance. For studies like ours with low allergen and endotoxin concentrations, the repeatability of these concentrations over a time period as long as 6 years is low and a single measurement does not accurately reflect the true long-term exposure in the homes. [ABSTRACT FROM AUTHOR]

A method was developed to analyse linear alkylbenzene sulfonates (C10–C13 LAS) in vacuumed floor dust in office buildings by the use of HPLC chromatography. Floor dust was sampled with a specially designed vacuum cleaner and fractionated into fibres and particles. The content of LAS in the particle fraction of floor dust sampled from seven different public buildings varied between 34 μg LAS g−1 dust and 1500 μg LAS g−1 dust, while the content of the fibre fractions was generally higher with up to 3500 μg LAS g−1 dust. The use of a cleaning agent with LAS resulted in increases approximately 30% of the amount of LAS in the floor dust after floor wash relative to just before floor wash. However, the most important source of LAS in the indoor floor dust appeared to be residues of detergent in clothing. Thus, a newly washed shirt contained 2960 μg LAS g−1 clothing. The analysis of the office dust samples indicated that LAS (and probably other detergents) might be of importance for the indoor environment. [Copyright &y& Elsevier]

Microorganisms residing in the human respiratory tract can be exhaled, and they constitute a part of environmental microbiotas. However, the expiratory microbiota community and its associations with environmental microbiotas remain poorly understood. Here, expiratory bacteria and fungi and the corresponding microbiotas from the living environments were characterized by DNA amplicon sequencing of residents' exhaled breath condensate (EBC) and environmental samples collected from 14 residences in Nanjing, China. The microbiotas of EBC samples, with a substantial heterogeneity, were found to be as diverse as those of skin, floor dust, and airborne microbiotas. Model fitting results demonstrated the role of stochastic processes in the assembly of the expiratory microbiota. Using a fast expectation-maximization algorithm, microbial community analysis revealed that expiratory microbiotas were differentially associated with other types of microbiotas in a type-dependent and residence-specific manner. Importantly, the expiratory bacteria showed a composition similarity with airborne bacteria in the bathroom and kitchen environments with an average of 12.60%, while the expiratory fungi showed a 53.99% composition similarity with the floor dust fungi. These differential patterns indicate different relationships between expiratory microbiotas and the airborne microbiotas and floor dust microbiotas. The results here illustrated for the first time the associations between expiratory microbiotas and indoor microbiotas, showing a potential microbial exchange between the respiratory tract and indoor environment. Thus, improved hygiene and ventilation practices can be implemented to optimize the indoor microbial exposome, especially in indoor bathrooms and kitchens.

Indoor dust has been postulated as an important matrix for residential pesticide exposure. However, there is a lack of information on presence, concentrations and determinants of multiple pesticides in dust in residential homes close to treated fields. Our objective was to characterize the spatial and temporal variance of pesticides in house dust, study the use of doormats and floors as proxies for pesticides in indoor dust and identify determinants of occurrence and concentrations. Homes within 250 m from selected bulb fields were invited to participate. Homes within 20 km from these fields but not having agricultural fields within 500 m were selected as controls. House dust was vacuumed in all homes from floors (VFD) and from newly placed clean doormats (DDM). Sampling was done during two periods, when pesticides are used and not-used. For determination of 46 prioritized pesticides, a multi-residue extraction method was used. Most statistical analyses are focused on the 12 and 14 pesticides that were detected in >40% of DDM and VFD samples, respectively. Mixed models were used to evaluate relationships between possible determinants and pesticides occurrence and concentrations in DDM and VFD. 17 pesticides were detected in more than 50% of the homes in both matrixes. Concentrations differed by about a factor five between use and non-use periods among homes within 250 m of fields and between these homes and controls. For 7 pesticides there was a moderate to strong correlation (Spearman rho 0.30-0.75) between concentrations in DDM and VFD. Distance to agricultural fields and air concentrations were among the most relevant predictors for occurrence and levels of a given pesticide in DDM. Concentrations in dust are overall higher during application periods and closer to fields (<250 m) than further away. The omnipresence of pesticides in dust lead to residents being exposed all year round., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background Previous studies have shown a high prevalence of atopic diseases among school children in the community of Sør-Varanger. Moreover, animal dander followed by pollen and house dust mite, were the most common allergens in skin prick texts. Objective To assess the allergen content in homes (living-rooms and mattresses) and classrooms of children living in an arctic area at 70° north. The presence of allergens in homes and schools and their relationship to atopy was of particular interest. Methods Dust samples from 38 homes and seven schools in northern Norway were collected by vacuum cleaning. The presence of allergens of dog, birch, timothy. Cladosporium herbarum, codfish and hen egg-white was investigated by radio-allergosorbent test (RAST) inhibition and the presence of major allergens of cat Felis domesticus (Fel d I) and house dust mites (HDM) Dermatophagoides pteronyssinus (Dcr p I) and Dermatophagoides farinae (Der f I) by enzyme-linked immunosorbent assay (ELISA). Results Mattresses contained significantly more dust per unit area than living-rooms and classrooms. No statistically significant differences in allergen content for dog, birch, timothy, Cladosporium, codfish and hen egg-white were seen between HDM-sensitized and non-atopic children. Most dust samples contained dog allergens with the highest allergenic activity found in living-rooms of those keeping dogs. An increased level of Fel d I was detected in only one of 38 samples from living-rooms (this family kept a cat) and in 25 of 38 samples from mattresses with ranges from 24 to 84 ng/m². The highest concentrations were found in mattresses of children keeping cats. Increased levels (≥: 25 ng/m²) of Der p I were found only in homes and virtually only in mattresses of HDM-sensitized children. An increased level of Der fl was found in only one case, i.e. in the mattress of an HDM-sensitized child where additionally Der p I and HDMs were demonstrated microscopically. When relating Der p I to HDM-sensitization an odds ratio of more than 16 (95% CI: 1.6-394.3) was found. All extracts from living-rooms included codfish allergens. Low RAST inhibition values were detected for hen egg-white, Cladosporium, birch and timothy pollen in most samples. Furthermore, the study demonstrated that dust from schools was relatively free of allergens. Conclusion Previous findings indicating that the main allergen exposure problem in this geographical area is that of pet allergens were confirmed. [ABSTRACT FROM AUTHOR]

The presence of indoor allergetis in Finnish homes was studied for the first time. Dust samples (n=30) were collected by vacuuming a 1 m² area from a living-room carpet in 30 apartments divided into three groups: homes with cats (n = 10), homes with dogs (n = 10). and homes without pets (n = 10). The levels of major cat (Fel d 1). dog (Can f 1), and house-dust-mite (Der p 1) allergens were analyzed by two-site ELISA methods. Der p 1 levels were below the detection limit in all dust samples. In the homes with cats or dogs, Fel d 1 and Can f 1 levels ranged from 147 to 2800 µg/g (geometric mean 567 µg/g), and from 86 to 1400 µg/g (geometric mean 296 µg/g), respectively, being slightly higher than those reported elsewhere. Low allergen levels, mainly below 3 (µg/g. were also detected in the homes without pets, indicating the transfer of allergens from place to place. However, in 25% of these samples, allergen levels exceeded the proposed threshold levels for cat or dog sensitization. The presence of pets was the most significant factor affecting cat and dog allergen levels in the house dust, and other factors, such as the amount of dust collected, residential time, and cleaning habits, had no or only a weak effect on allergen levels. [ABSTRACT FROM AUTHOR]

The levels of Cd, Cr, Cu, Fe, Mn, Pb and Zn were determined in floor dusts from mechanical (MRWs) and battery repairing workshops (BRWs) in Yazd, Iran. The study aimed to evaluate the anthropogenic contribution to the presence of heavy metals (HMs), the possible sources and the related risks that could arise from occupational exposure in the studied workplace microenvironments. Among the analyzed heavy metals, Cu, Pb and Zn exhibited enhanced concentrations in the floor dusts. The EF calculations showed an extremely severe enrichment of HMs, especially for Cd, Cu and Pb, while floor dusts were characterized as "extremely polluted" with regards to those metals. In any case, both EF and I geo values were significantly higher in the BRWs. These results were also supported by NIPI and PLI values, while contour maps of PLI values in both MRWs and BRWs outlined workshops in N-NE part of Yazd as more impacted compared to other spatial locations. Principal component analysis (PCA) and Pearson's correlation outscored workshops activities as the principal sources of heavy metals. The health risk assessment suggested considerable non-carcinogenic risks regarding Pb in the BRWs which exhibited HQ ing (mean 2.91) and HI (mean 3.03) values higher than safe level. Regarding carcinogenic risks, CR values for both Cd and Cr were below the safe level (1.0 × 10−6). The occupational exposure to Pb was evaluated through the predicted BLL values, where with averages of 3.33 μg/dl and 21.4 μg/dl for MRWs and BRWs workers, respectively, indicated a severe Pb exposure for BRWs workers. Unlabelled Image • Cu, Pb and Zn exhibited the higher concentrations in the floor dusts. • Floor dusts from BRWs presented substantially higher heavy metal contents. • Cd, Cu, Pb and Zn were the metals originating from workshops activities. • Pb was the dominant contributor to cumulative non-carcinogenic risk. [ABSTRACT FROM AUTHOR]

The occurrence levels of eight polybrominated diphenyl ethers (PBDEs) and four novel brominated flame retardants (NBFRs) were determined and compared in indoor dust from different microenvironments (21 homes, 23 offices and 16 day care centers) in Beijing, China. Concentrations of ∑ 8 PBDEs in dust were 430-17,000 ng/g, 690-8600 ng/g, and 90-2300 ng/g for homes, offices, and day care centers, respectively, and were dominated by BDE-209. Concentrations of ∑ 4 NBFRs ranged from 310 to 17,000 ng/g, 300 to 4300 ng/g, and not detected to 500 ng/g for homes, offices, and day care centers, respectively, and were dominated by bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (BEH-TEBP) and decabromodiphenylethane (DBDPE) across microenvironments. The results showed an increasing detection and elevated concentration of NBFRs (especially BEH-TEBP), indicating that monitoring of NBFRs in dust samples should be of concern in future studies. A notable finding was that the BFR concentrations in dust samples from day care centers were generally one order of magnitude lower than those from homes and offices in the present study. This implies that previous estimates of toddler exposure via dust ingestion on data from homes may be overestimated. Concentrations of BDE-209 and ∑ 8 PBDEs were found to be significantly higher in elevated surface dust than floor dust from day care centers. The estimates of daily intakes of BFRs via dust ingestion for Chinese adults and toddlers using Monte Carlo analysis were 2-5 orders of magnitude lower than the corresponding reference daily intakes., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Markers for microbial groups are commonly measured in house dust samples to assess indoor exposure to microbes in studies on asthma and allergy. However, little is known about the sources of different microbes. A better understanding of the nature and origin of microbes present in the immediate environment of human beings is crucial if one wants to elucidate protective as well as adverse effects on human health. Objective: To determine the extent to which the bacterial composition of mattress and floor dust reflects the presence of the human body in relation to other environmental sources. Methods: House dust and skin surface swab samples of occupants in 4 homes were collected and analyzed for their bacterial content, using a culture-independent methodology. Bacterial sequences analyzed from the different house dusts and skin surface swabs represented random samples of bacteria present in a given sample. Highly similar sequences were grouped to assess biodiversity and to draw conclusions about the sources of bacteria. Results: The bacterial flora in the house dust samples was found to be highly diverse and dominated by gram-positive bacteria. To a considerable extent, the presence of different bacterial groups was attributed to human sources. In the individuals'' mattress dust samples, 69% to 88% of the bacterial sequences analyzed were associated with human origins. The respective percentages for the individual floor dusts ranged from 45% to 55%. Conclusion: Our study indicates that human-derived bacteria account for a large part of the mainly gram-positive bacterial content in house dust. [Copyright &y& Elsevier]

The lead particle content of floor dust in a housing unit scheduled for interior lead paint hazard removal was characterised microscopically to identify the contributing source(s) of the lead. It was hypothesised that elevated levels of lead in the dust resulted from the deterioration of the lead-based paint on the indoor surfaces. The question of lead particle source attribution was addressed using a combination of scanning electron microscopy (SEM) and energy dispersive X-rayspectroscopy (EDS). SEM/EDS provided data on the size, shape, and composition of the individual lead-containing dust particles. The floordusts which were analysed contained a variety of lead particle typesand eight of these types from several rooms exhibited unique morphological and/or chemical characteristics. These were variously classified as lead paint particles. The lead levels in the floor dusts prior to the abatement were >/= 100 5 g-ft-2. The floor dust lead concentrations immediately following the abatement were all less than the pre-abatement levels, but a re-sampling 2 months after the abatement found that the amount of lead in two of the rooms was approximately 3 and 4.5 times higher than the levels prior to the abatement. SEM/EDS analysis of the floor dusts samples collected 2 months after the abatement showed that in these two rooms the constituent particulate lead differed from that in any of the pre-abatement dusts. Following attempts to identify possible sources of recontamination, it was found that this previously unidentified particulate lead was consistent in form with lead scraped from the interior of one of the radiators which had been removed from the complex some time after the abatement. Residual water spilling from the radiators during the course of removal was, in all likelihood, the cause of the unexpectedly elevateddust lead levels. [ABSTRACT FROM AUTHOR]