Household Vacuum Cleaner Research Articles

Network Analysis of Two-Stage Customer Decisions with Preference-Guided Market Segmentation

Abstract Network-based analyses have shown their effectiveness in understanding customer preferences through interactions and relationships between customers and products, particularly for tailored product design. There is limited research on applying this analysis to diverse customers with varied preferences. This paper introduces a market-segmented network modeling approach, guided by customer preference, to explore heterogeneity in customers' two-stage decision-making process: consideration-then-choice. In heterogeneous markets, like household appliances, even customers with similar characteristics or purchasing similar products can exhibit different decision-making processes. Therefore, In this method, we segment customers into groups based on preferences rather than just characteristics, allowing for more accurate choice modeling. Using Joint Correspondence Analysis, we identify associations between customer attributes and preferred products, characterizing market segments through clustering. We then build individual bipartite customer-product networks and apply the Exponential Random Graph Model to compare the product features influencing customer considerations and choices in various market segments. Using a US household vacuum cleaner survey, our method detected different customer preferences for the same product attribute at different decision-making stages. The market-segmentation model outperforms the non-segmented benchmark in prediction, highlighting its accuracy in predicting varied customer behaviors. This study underscores the vital role of preference-guided segmentation in product design, illustrating how a deeper understanding of customer preferences at different decision stages can inform and refine design strategies, ensuring products are more closely aligned with the dynamic needs and tastes of diverse markets.

HYKYHT: A versatile, affordable, and open-source 3D-printed liquid aspiration system

This paper aims to provide the details for making affordable single and multichannel liquid aspirators for wet labs. A liquid aspirator is a basic laboratory device that can cost several hundred Euros. We present a < €25 3D print solution that performs equally well in daily lab routines and is compatible with various vacuum sources, including an aquarium pump or household vacuum cleaner. Presently, commercial aspirators cost more than a decent entry-level 3D printer capable of producing all the parts listed in this manuscript. The models were designed with Tinkercad, with easy printing and minimal support in mind. The versatility and the ultra-low-cost solution we presented could ease the daily workflow of researchers in various research fields. Furthermore, it is valuable to high school or undergraduate student labs and community wet labs for science enthusiasts, where funding is generally limited.

An AIGC-empowered methodology to product color matching design

With the emergence of various generative AI applications, artificial intelligence-generated content (AIGC) demonstrates positive potential for design activities. However, few scholars have proposed a practical AIGC-based design methodology. This paper introduces an AIGC-empowered methodology for product color-matching design. ChatGPT generates target imageries describing the design features, and Midjourney constructs a shape sample database based on these imageries, identifying representative shapes through consumer perceptual questionnaires. Meanwhile, three Midjourney-based color image generation methods are proposed to generate color images that match the target imageries, and an application is developed to extract the dominant colors from these images. Finally, based on the color harmony theory, the optimal color combinations are derived from the extracted dominant colors and applied to the representative shape to generate color-matching alternatives. AHP-based expert evaluation (Evaluation_1) and consumer perceptual evaluation (Evaluation_2) are employed to ascertain the optimal design solution. This paper uses the household vacuum cleaner as an example to demonstrate the proposed color-matching methodology. Consistent evaluation results are obtained, supported by a significant Pearson correlation coefficient. Research findings suggest that AIGC has the potential to revolutionize traditional product color-matching design. Additionally, the methodology highlights the collaborative potential between generative AIs and conventional computer-aided design tools.

Sampling method for house dust using a mop and determination of OPFRs, phthalates, and alternative plasticisers in house dust

ABSTRACT Semi-volatile organic compounds (SVOCs), such as phthalates and organophosphate flame retardants (OPFRs), are used in plastic products and electrical and electronic applications as plasticisers or flame retardants. There has been a growing concern that exposure to SVOCs can have an adverse impact on human health. Several large-scale epidemiological studies employ the sampling of house dust using household vacuum cleaners as the standard method. However, in this method, house dust samples might be contaminated by flame retardants and plasticisers because of the presence of these chemicals in the plastic materials of cleaners. Therefore, this study aimed to develop a low-cost, easy-to-distribute sampling method to collect house dust using a mop and analyse OPFRs, phthalate esters, and alternative plasticisers in house dust. Our findings show that the proposed mop sampling method can be easily distributable and lower contamination from a sampling tool. Moreover, the proposed house dust sampling method is extremely useful for a large-scale survey such as a cohort study.

Characteristics and sources of Pb exposure via household dust from the urban area of Shanghai, China

Household dust has been considered as an important pathway for children's environmental Pb exposure. Shanghai was one of the first cities in China that removed Pb from petrol and has been shown in our previous study to have the lowest childhood blood Pb levels in China. This study therefore examines household dust Pb (PbHD) in Shanghai in order to determine the extent and exposure risks of PbHD. Household vacuum cleaner dust samples (n = 40) were collected and analyzed for total Pb concentration, bio-accessible Pb concentration and Pb isotopic compositions (PbIC). The mean concentration of PbHD was 195 mg/kg, which is between 7 and 10 times the Pb concentration of background soil samples from Shanghai. Among the investigated homes, those living in neighborhoods with lower average estate prices have higher dust Pb exposure risks for children. Bio-accessibility of Pb in household dust ranged between 53 and 91%, with a mean value of 71%. Analysis of PbIC of household dust samples (208Pb/206Pb: 2.1096 ± 0.0054; 207Pb/206Pb: 0.8648 ± 0.0025) are a close match to PbIC of coal combustion and solid waste incineration and fit well with those of outdoor air PbIC and urban surface soil PbIC of Shanghai. The study shows that children living in Shanghai are subject to PbHD exposure, with children living in the homes with lower average price having increased susceptibility to PbHD exposure. The data indicate that PbHD is derived primarily from contemporary coal combustion and solid waste incineration rather than common legacy Pb sources (e.g., Pb petrol and paint). Practices including closing doors and windows on days with poor air quality or high wind and preventing shoe wearing inside homes will aid in minimizing outdoor surface soil and ambient particulate intrusion indoors.

Airborne SARS-CoV-2 in home and hospital environments investigated with a high-powered air sampler

BackgroundThe initial aim was to study the effects of face masks worn by recently infected individuals on the airborne spread of SARS-CoV-2, but findings motivated us to proceed with comparing the presence of SARS-CoV-2 in air samples near infected individuals at home with those near infected intensive care unit (ICU) patients.AimTo assess the presence of SARS-CoV-2 in the air of homes of infected individuals and in ICU rooms of critically ill patients with COVID-19 who were undergoing different forms of potential aerosol-generating medical procedures.MethodsA high-volume air sampler method was developed that used a household vacuum cleaner with surgical face masks serving as sample filters. SARS-CoV-2 RNA was harvested from these filters and analysed by polymerase chain reaction. Fog experiments were performed to visualize the airflow around the air sampler. Air samples were acquired in close proximity of infected individuals, with or without wearing face masks, in their homes. Environmental air samples remote from these infected individuals were also obtained, plus samples near patients in the ICU undergoing potential aerosol-generating medical procedures.FindingsWearing a face mask resulted in a delayed and reduced flow of the fog into the air sampler. Face masks worn by infected individuals were found to contain SARS-CoV-2 RNA in 71% of cases. SARS-CoV-2 was detected in air samples regardless of mask experiments. The proportion of positive air samples was higher in the homes (29/41; 70.7%) than in the ICU (4/17; 23.5%) (P < 0.01).ConclusionSARS-CoV-2 RNA could be detected in air samples by using a vacuum cleaner based air sampler method. Air samples in the home environment of recently infected individuals contained SARS-CoV-2 RNA nearly three times more frequently by comparison with those obtained in ICU rooms during potential aerosol-generating medical procedures.

Design and simulation of components of vacuum forming machine using household vacuum cleaner

Plastic products ranging from toothbrushes to smartphones are an inseparable commodity in daily human life and their impact cannot be underestimated. This paper aims to design and simulate the vacuum forming process using readily available materials in context of Nepal. Vacuum forming process is a thermoforming process where the heated plastic sheet derives the shape of the mold through the application of vacuum and is used to make packaging products and other household products. Simulations were done to find out the optimum distance between the plastic sheet and the heater, arrangement of the wire in the heater, load bearing capacity of the design and the flow of vacuum in the arrangement. Nichrome wire coiled as heater coil is used as the heating material and laid in a spiral path with the plastic sheet 35mm below provided the best heating results and 1800W vacuum cleaner provided the necessary pressure of 85-90kPa and velocities of 100- 115m/s while the steel posts provided adequate strength.

Efficiency of an Air Cleaner Device in Reducing Aerosol Particulate Matter (PM) in Indoor Environments.

Indoor air quality (IAQ) in household environments is mandatory since people spend most of their time in indoor environments. In order to guarantee a healthy environment, air purification devices are often employed. In the present work, a commercial household vacuum cleaner has been tested in order to verify its efficiency in reducing the mass concentration and particle number of aerosol particulate matter (PM). The efficiency has been tested measuring, while the instrument was working, PM10 (particles with aerodynamic diameter less than 10 μm), PM2.5 (particles with aerodynamic diameter less than 2.5 μm), PM1 (particles with aerodynamic diameter less than 1 μm), and 7 size-fractions in the range between 0.3 and >10 μm. Measurements have been carried out by means of a portable optical particle counter instrument and simulating the working conditions typical of a household environment. It has been found that the tested commercial device significantly reduces both PM concentrations and particle number, especially in the finest fraction, i.e., particles in the range 0.3–0.5 μm, allowing an improvement of indoor air quality.

Short-, medium-, and long-chain chlorinated paraffins in South African indoor dust and cat hair

Polychlorinated n-alkanes or chlorinated paraffins (CPs) contain a magnitude of structural isomers and are categorized as short-chain (SCCPs), medium-chain (MCCPs), and long-chain (LCCPs) CPs, according to the carbon chain lengths. In this study the ƩSCCPs, ƩMCCPs, and ƩLCCP concentrations are reported for South African indoor dust and pet cat hair. The median concentrations of the ƩCPs (C9–C37) ranged from 33 to 663 μg/g for freshly collected dust (FD), 36–488 μg/g for dust collected from household vacuum cleaner bags (VD), and 1.2–15 μg/g for cat hair (CH) samples. MCCPs were the dominant CP group, followed by SCCPs and LCCPs. The ƩMCCP concentration ranged from 13 to 498 μg/g in dust and 0.6–6.5 μg/g in cat hair. SCCPs with shorter carbon chains and lower chlorine substitution were observed in cat hair. LCCPs with carbon chains > C20 were detected in dust and hair samples, possibly indicating the use of wax grade LCCP formulations. Non-traditional Kendrick mass defect plots were used to obtain information on the magnitude of CPs and provide evidence of possible interfering compounds. This is the first report on the occurrence of SCCPs, MCCPs, and LCCPs in the South African indoor environment.

HEPA급 필터 등급에 따른 가정용 진공청소기의 미세먼지방출량 연구

HEPA급 필터 등급에 따른 가정용 진공청소기의 미세먼지방출량 연구

Short-chain and medium-chain chlorinated paraffins in Canadian house dust and NIST SRM 2585.

A method for the analysis of short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) in house dust was developed. The method is based on sonication extraction, sample cleanup by solid phase extraction (SPE), and separation and detection by gas chromatography coupled with mass spectrometry (GC/MS) operated in electron capture negative ion (ECNI) chemical ionization mode. The method is sensitive, with method detection limits (MDLs) down to 0.22μg/g for SCCPs and 0.55μg/g for MCCPs. The overall recoveries of the method were 104 (± 11)% and 108 (± 16)% for SCCPs and MCCPs, respectively. The method was successfully applied to the analysis of SCCPs and MCCPs in NIST standard reference material (SRM 2585, organic contaminants in house dust) and a subset of house dust samples collected under the Canadian House Dust Study (CHDS). Average concentrations of SCCPs and MCCPs in SRM 2585 (n = 12 replicates) were 7.58 (± 0.43) μg/g for SCCPs and 16.4 (± 2.1) μg/g for MCCPs, respectively. A comparison was made between CP concentrations in paired dust samples collected using two different methods from the same homes: fresh or "active" dust (FD) collected by technicians and a sample taken from the household vacuum cleaner (HD). Spearman rank analysis showed a significant positive correlation (p < 0.01) between FD and HD samples for both MCCPs and SCCPs. CPs were detected in every house dust sample (n = 48 HD samples), with median (range) concentrations of 6.2 (4.0 - 57) μg/g and 19 (5.9-901) μg/g for SCCPs and MCCPs, respectively. Widely scattered CP levels and 100% detection frequency in this preliminary set of 48 HD samples suggest a wide variability in Canadian household exposures to CPs.

Size-resolved particle measurements of polybrominated diphenyl ethers indoors: Implications for sources and human exposure.

Polybrominated diphenyl ethers (PBDEs) are flame retardant polymer additives that are widely detected in outdoor and indoor environments. Release of PBDEs from consumer products leads to high concentrations indoors, but mechanisms of release are poorly understood. Although ingestion of dust is a well-studied indoor PBDE exposure route, the importance of inhalation exposure is uncertain. To address these unknowns, dust was collected from household vacuum cleaners, and suspended particulate matter was collected from the same homes in St. John's, Newfoundland, Canada, using a cascade impactor. Size-fractionated particulate matter samples (0.01-18 μm diameter) were analyzed for PBDEs. The sum of PBDEs in all particulate matter ranged from 8.7 ± 0.5 to 15.7 ± 0.5 pg/m3 , with >50% of PBDE mass in respirable particulate matter (<1 μm). Mass loadings as a function of particle size suggested that both abrasion and off-gassing led to the presence of PBDEs in particulate matter. Variability in the particulate matter mass loadings indicated that emission mechanisms were both product- and location-dependent. Congener profiles in colocated vacuum dust and particulate matter samples were different, indicating that vacuum dust cannot accurately predict PBDE congeners in respirable particulate matter. A calculated lower limit inhalation exposure to PBDEs (0.19 ng/d) is lower than exposure via diet or ingestion of dust, although the different biochemical pathways for inhalation compared with ingestion may have different biological effects. The present study highlights the importance of contaminant analysis in size-fractionated particulate matter to assess human exposure via inhalation compared with traditional vacuum dust methods. Environ Toxicol Chem 2018;37:481-490. © 2017 SETAC.

Expanding the number of phthalates monitored in house dust

ABSTRACTPhthalates have been used as plasticisers for several decades in various industry and consumer products. A method was developed for the determination of 13 not commonly monitored phthalates in household dust. The method was based on solvent extraction using sonication, sample clean-up by solid phase extraction (SPE), and analysis using isotope dilution gas chromatography-tandem mass spectrometry (GC/MS/MS). The method was applied to the analysis of dust samples collected using two vacuum sampling techniques from 38 urban Canadian homes: a sample of fresh or ‘active’ dust (FD) collected by technicians and a composite sample taken from the household vacuum cleaner (HD). Spearman rank correlations between HD and FD samples were significant for six phthalates with median concentrations above their method detection limits (MDLs), suggesting that the HD samples provide comparable results with FD samples. Seven phthalates were detected and quantified in a Canada-wide set of 126 household dust samples, among which six phthalates were detected at frequencies higher than 87%, with median (range) concentrations of 1.9 (<0.42–240) (μg/g) for diisohexyl phthalate (DIHxP), 3.8 (<0.16–260) (μg/g) for di-n-heptyl phthalate (DHepP), 6.6 (<1.1–1170) (μg/g) for diisooctyl phthalate (DIOP), 1.1 (<0.12–390) (μg/g) for di-n-octyl phthalate (DOP), 6.3 (<0.16–430) (μg/g) for dinonyl phthalate (DNP), and 1.8 (<0.18–850) (μg/g) for di-n-decyl phthalate (DDP). High detection frequencies and widely scattered concentration levels of these phthalates in this preliminary set of 126 samples suggested a high variability in potential exposure to phthalates in Canadian homes. NIST SRM 2585 (organic contaminants in house dust) was also analysed; eight phthalates were detected, with concentrations ranging from 6.0 μg/g for DOP to 79 μg/g for DIHxP. The results from SRM 2585 may contribute to the certification of phthalate concentration values in this SRM.

Application of water-soluble nanofilters for collection of airborne Mycobacterium tuberculosis DNA in hospital wards

A simple inexpensive technique for collection of airborne biomarkers of nosocomial infections is described. Biomarkers were collected on water-soluble electrospun nanofilters attached to a household vacuum cleaner from 6-10m(3) of air in 10-15min within several wards of a tuberculosis clinic. Filters were then dissolved in water and tested for the presence of the IS6110 and regX3 genes of Mycobacterium tuberculosis (MTB) using real-time polymerase chain reaction. It was demonstrated that trace amounts of airborne MTB DNA (>3gene copies/m(3)) were always present in the air and on the surfaces in the wards occupied with tuberculosis patients having positive smear tests.

Non-PBDE halogenated flame retardants in Canadian indoor house dust: sampling, analysis, and occurrence.

An analytical method was developed for the measurement of 18 novel halogenated flame retardants in house dust. Sample preparation was based on ultrasound-assisted solvent extraction and clean up with solid phase extraction (SPE). Sample extracts were analyzed by gas chromatography-mass spectrometry (GC/MS) operated in electron capture negative ion (ECNI) chemical ionization mode. Baseline data from 351 fresh (active) dust samples collected under the Canadian House Dust Study (CHDS) revealed that five out of 18 target chemicals were present with detection frequencies higher than 90%. Median (range) concentrations for these five compounds were as follows: 104 (<1.5-13,000) ng/g for 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB), 8.5 (<1.7-2390) ng/g for 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), 10.2 (<1.7-430) ng/g for hexabromobenzene (HBB), 2.9 (<1.2-1410) ng/g for syn-dechlorane plus (syn-DP) and 5.6 (<1.9-1570) ng/g for anti-dechlorane plus (anti-DP). A comparison of two sampling methods in a subset of 40 homes showed significant positive correlations between samples of "active" dust and samples taken directly from the household vacuum cleaner for all target compounds having median values above their corresponding method detection limits (MDLs). In addition, the method was also applied to the analysis of the targeted compounds in National Institute of Standards and Technology (NIST) standard reference material (SRM 2585, organic contaminants in house dust). Results from the current study could contribute to the potential certification of target chemicals in SRM 2585.

Abstract 831: In utero polycyclic aromatic hydrocarbons exposure and genome-wide DNA methylation modifications at birth in children who develop acute lymphoblastic leukemia

Abstract Introduction Previously, residential dust content of polycyclic aromatic hydrocarbons (PAHs) was associated with an increased risk of acute lymphoblastic childhood leukemia (ALL), and PAHs exposure levels have been associated with differentially methylated regions (DMRs) in candidate genes studies. Thus, we hypothesized that in utero exposure to residential PAHs may be associated with genome-wide DMRs in genes that may influence ALL development. Methods PAHs were measured in dust samples collected using a high-volume surface sampler or household vacuum cleaners from homes of California Childhood Leukemia Study participants who have lived in the same home since diagnosis. The different PAHs were summed according to their toxic equivalency. DNA was extracted from archived neonatal blood spots of participants, then treated with bisulfite and assayed on Illumina Infinium 450K genome-wide DNA methylation arrays. Following removal of cross-reacting probes, SNP-related and polymorphic CpGs, we analyzed the association of residential PAH levels with methylation intensity of 319,265 CpGs in two independent case-only datasets (model #1: set 1 cases n = 84, set 2 cases n = 51). We used a false discovery rate with random resampling to reduce the number of false-positive findings and cross-validated the results between sets. This first step of the analysis gave 11 significant and sign concordant CpGs. Then we assessed interactions between case/control status and PAHs levels with methylation intensities at those 11 CpGs in set 1 (model #2: total cases and controls n = 306). Models were adjusted for cell mixture, sex, gestational age, race and the first 2 principal components of the models’ residuals. Results In model #1, methylation levels at 11 CpGs were significantly associated with residential PAH levels and sign concordant in both sets with a corresponding q-value &amp;lt; 10−08. In model #2, the interaction terms between PAH and case/control status were significant (p&amp;lt;0.05) in 7 of these 11 CpGs, and the 3 most significant were: cg13484813 (p &amp;lt;0.001) in LGR5 (chr12q21.1) which is differentially expressed in pre-B cell vs. leukemia cells; cg23196133 (p &amp;lt;0.01) in ZBTB4 (chr17p13.1) which is a transcription factor linked to p53; and cg07617339 (p &amp;lt;0.01) in ATF6B (chr6p21.3) which encodes a transcription factor. Conclusions For the first time, our genome-wide methylation investigation found that residential PAH levels were associated with 11 CpGs at birth among children who later developed ALL. Moreover, the future cases had significantly different DNA methylation responses to PAH exposures than the unaffected controls for 7 CpGs. This may suggest a case/control difference present at birth in the sensitivity to PAHs in particular cell-cycle and tumor-suppressor genes. These CpGs may be good candidates to further investigate with respect to leukemogenesis. Citation Format: Semira Gonseth, Todd P. Whitehead, Ritu Roy, E. Andres Houseman, Adam J. de Smith, Mi Zhou, Seung-Tae Lee, Margaret R. Wrensch, Stephen M. Rappaport, Catherine Metayer, Joseph L. Wiemels. In utero polycyclic aromatic hydrocarbons exposure and genome-wide DNA methylation modifications at birth in children who develop acute lymphoblastic leukemia. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 831. doi:10.1158/1538-7445.AM2015-831

Concentrations of Persistent Organic Pollutants in California Children's Whole Blood and Residential Dust.

We evaluated relationships between persistent organic pollutant (POP) levels in the blood of children with leukemia and POP levels in dust from their household vacuum cleaners. Blood and dust were collected from participants of the California Childhood Leukemia Study at various intervals from 1999 to 2007 and analyzed for two polybrominated diphenyl ethers (PBDEs), two polychlorinated biphenyls (PCBs), and two organochlorine pesticides using gas chromatography-mass spectrometry. Due to small blood sample volumes (100 μL), dichlorodiphenyldichloroethylene (DDE) and BDE-153 were the only analytes with detection frequencies above 70%. For each analyte, depending on its detection frequency, a multivariable linear or logistic regression model was used to evaluate the relationship between POP levels in blood and dust, adjusting for child's age, ethnicity, and breastfeeding duration; mother's country of origin; household annual income; and blood sampling date. In linear regression, concentrations of BDE-153 in blood and dust were positively associated; whereas, DDE concentrations in blood were positively associated with breastfeeding, maternal birth outside the U.S., and Hispanic ethnicity, but not with corresponding dust-DDE concentrations. The probability of PCB-153 detection in a child's blood was marginally associated with dust-PCB-153 concentrations (p = 0.08) in logistic regression and significantly associated with breastfeeding. Our findings suggest that dust ingestion is a source of children's exposure to certain POPs.

가정용 진공청소기 사용에 의한 부유 미세먼지와 부유 미생물의 배출특성

가정용 진공청소기 사용에 의한 부유 미세먼지와 부유 미생물의 배출특성

사이클론 청소기 내부 유동에 관한 수치해석적 연구

가정용 진공청소기는 기본적으로 집진장치(dust collector), 프리 필터(pre filter), 모터(motor), 배기 필터(exhaust filter)의 구조를 가지며, 흡입된 먼지가 포함된 공기는 이러한 구조를 지나 깨끗한 공기가 되어 대기로 방출된다. 본 연구에서는 실생활에 사용되고 있는 구조가 다른 2개의 사이클론 청소기를 선정하여 사이클론 청소기 내 집진장치의 내부 공기 유동에 대해 전산유체역학을 적용하여 집진성능을 평가하고자 하였다. 사이클론 콘(cyclone cone) 영역에서 공기의 유선(streamline)을 해석한 결과, 사이클론 콘 영역에서 상당한 선회수를 가지는 것을 확인하였다. 특정 형상의 청소기에 대한 전산해석 결과에서 출구에서의 속도 분포가 매우 불균일한 결과를 나타내었고 이로 인해 집진성능에 악영향이 나타남이 파악되었다. 이 문제를 해결하기 위해 집진장치 형상에 추가적으로 배플을 설치하여, 달라진 속도 분포에 의한 속도 RMS (Root Mean Square) 값의 개선을 평가하였다. General household vacuum cleaners consist of dust collector, pre filter, motor and exhaust filter, and the filtered clean air is discharged to the atmosphere. By using the CFD methods, we estimated the internal flow in two types of commercial cyclone vacuum cleaners to evaluate the dust collection performance. From the analysis, it was known that the number of revolution had higher values in cyclone cone region. CFD analysis in a specific showed non-uniform velocity distribution at outlet, which results in the deterioration of particle collection performance. In order to improve flow condition, the installation of baffle was proposed and the values of velocity RMS were estimated.

Polycyclic aromatic hydrocarbons in residential dust and risk of childhood acute lymphoblastic leukemia

Several polycyclic aromatic hydrocarbons (PAHs) are known or probable human carcinogens. We evaluated the relationship between PAH exposure and risk of childhood acute lymphoblastic leukemia (ALL) using concentrations in residential dust as an exposure indicator. We conducted a population-based case-control study (251 ALL cases, 306 birth-certificate controls) in Northern and Central California from 2001 to 2007. We collected residential dust using a high volume small surface sampler (HVS3) (n=185 cases, 212 controls) or by sampling from participants׳ household vacuum cleaners (n=66 cases, 94 controls). We evaluated log-transformed concentrations of 9 individual PAHs, the summed PAHs, and the summed PAHs weighted by their carcinogenic potency (the toxic equivalence). We calculated odds ratios (ORs) and 95% confidence intervals (CI) using logistic regression adjusting for demographic characteristics and duration between diagnosis/reference date and dust collection. Among participants with HVS3 dust, risk of ALL was not associated with increasing concentration of any PAHs based on OR perln(ng/g). Among participants with vacuum dust, we observed positive associations between ALL risk and increasing concentrations of benzo[a]pyrene (OR perln[ng/g]=1.42, 95% CI=0.95, 2.12), dibenzo[a,h]anthracene (OR=1.98, 95% CI=1.11, 3.55), benzo[k]fluoranthene (OR=1.71, 95% CI=0.91, 3.22), indeno[1,2,3-cd]pyrene (OR=1.81, 95% CI=1.04, 3.16), and the toxic equivalence (OR=2.35, 95% CI=1.18, 4.69). The increased ALL risk among participants with vacuum dust suggests that PAH exposure may increase the risk of childhood ALL; however, reasons for the different results based on HVS3 dust samples deserve further study.