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At least 55 records · Page 3Linked to original sources
PubMed1994

House dust mite allergen in bedroom floor dust and respiratory health of children with asthmatic symptoms.

The purpose of this study was to investigate the effects of house dust mite allergen in bedroom floor dust on respiratory health of children with asthmatic symptoms. Two hundred and twenty eight school children with reported attacks of shortness of breath with wheezing in the past year and/or with doctor-diagnosed asthma, were included in the study. Data on home characteristics, both past and present, were obtained. These included data on allergen avoidance measures because of the child's respiratory health. Dust samples were taken from the child's bedroom floor, and the allergen Der p I of the house dust mite Dermatophagoides pteronyssionus was measured. Health diaries were kept over 4 weeks. Acute respiratory symptoms and medication usage were recorded daily. Peak expiratory flow (PEF) was measured using Mini-Wright peak flow meters three times daily. Levels of Der p I in dust from carpeted floors were significantly higher than in dust from smooth floors. We found a positive relationship of Der p I levels, in floor dust collected from carpeted floors, with PEF-variability and also with the prevalence of wheeze, shortness of breath, and attacks of shortness of breath with wheezing during the observation period. The effects on peak flow variability was larger in children allergic to house dust than in children not allergic to house dust. Peak flow variability was significantly increased at exposure levels well below 10,000 ng Der p I.g-1 dust, which has been suggested to be a "threshold" for increased risk symptoms among sensitized asthmatics.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗
PubMed2006

[Research on impact of dust event frequency on atmosphere visibility variance: a case study of typical weather stations locating in the dust route to Beijing].

Relationship between dust event frequency and atmosphere visibility deviation is analyzed by using the data of daily visibility and various dust events in Beijing and other 13 typical weather stations locating in the dust events route to Beijing from 1971 to 2000. Results show that the visibility variance increases a standard deviation in the response to the dust event frequency decrease once. The influence of dust event to visibility comes from the high-frequency change of wind velocity. The change of wind velocity in one standard deviation can result in dust event frequency increasing by 30%. The high-frequency changes of near-surface wind influence the occurrence of dust event, and also the fluctuation of daily visibility deviation. The relationship between abnormal low visibility event and visibility deviation is in significant positive correlation. The increase of wind average distance leads to the enhance frequency of dust event and consequently the abnormal low visibility event. There are different relationships between abnormal low visibility event and floating dust, sandstorm and flying-dust respectively.

Air Pollutants↗
PubMed1997

Log-additive versus log-linear analysis of lead-contaminated house dust and children's blood-lead levels. Implications for residential dust-lead standards.

The Environmental Protection Agency has been mandated to develop a health-based standard for lead in residential dwellings in the United States. Prior estimates of the relationship between residential dust-lead levels and children's blood-lead concentrations have usually been obtained by using a log-linear regression of blood-lead concentration on levels of lead-contaminated house dust. It remains unknown, however, whether the log-linear model or a frequently cited alternative, the log-additive model, is the preferable regression method for analyzing these data. Secondary analysis of the Lead-in-Dust Study data was undertaken to compare log-additive with log-linear regression analysis for the purpose of developing a health-based dust lead standard. Specifically, we were interested in comparing the log-additive and log-linear analyses in their ability to characterize adequately the relationship of dust-lead loading on various surfaces with blood-lead concentrations among urban children and to develop a predictive model to estimate the risk that a child will develop an elevated blood-lead level on the basis of a known level of dust lead. We used two dust sampling methods, the Baltimore Repair and Maintenance (BRM) vacuum method and the wipe method, to compare the log-linear and log-additive models. The log-linear model was consistently superior to the log-additive model in its ability to explain the variability in the observed blood-lead concentrations of the studied children, for both the wipe sampler and the BRM sampler. In addition, the log-additive model often predicted only a limited increase in the probability of blood-lead concentrations exceeding 10 micrograms/dl as a result of doubling the dust-lead loading exposure, whereas the log-linear model consistently demonstrated a significant increase in the probability of blood-lead concentrations exceeding 10 micrograms/dl. BRM lead loading explained additional variability in blood lead above and beyond that explained by wipe loading for both carpeted and uncarpeted floors. In contrast, wipe-lead loading explained significant additional variability after adjustment for BRM loading for both uncarpeted floors and interior window sills. Although BRM loading better predicted children's blood-lead concentrations than did wipe loading, these differences were not statistically significant. We conclude that the log-linear model explained a greater percentage of the variability in blood-lead concentrations than did the log-additive model, indicating that the log-linear model should be the default model of choice for developing a dust-lead standard.

Air Pollution, Indoor↗
PubMed2003

Simultaneous extraction of di(2-ethylhexyl) phthalate and nonionic surfactants from house dust. Concentrations in floor dust from 15 Danish schools.

Static extraction, supercritical fluid extraction (SFE), pressurized liquid extraction (PLE) and Soxhlet extraction were compared for simultaneous extraction of di(2-ethylhexyl) phthalate (DEHP) and nonionic surfactants from house dust. Homogenized office floor dust from a vacuum cleaner dust bag ("standard dust") was used for the evaluation. One portion of the extracts was used for analysis of nonionic surfactants with LC-MS and another portion was used for DEHP analysis with GC-MS. The extraction yield of DEHP was comparable for all the methods whereas SFE and PLE were the most efficient extraction techniques for the nonionic surfactants. The PLE extraction was found most suitable as a routine method for simultaneous extraction of both types of compounds and was used in a field study of floor dust from 15 Danish schools. The mean concentration of DEHP in the school dust samples was approximately 4 times higher than observed in other studies of dust from homes in different countries. The concentrations of nonionic surfactants were one order of magnitude lower than soap and linear alkylbenzene sulfonates measured in other studies of floor dust from offices and other public buildings. However, for the first time nonionic surfactants have been identified in house dust.

Chromatography, Liquid↗
PubMed2001

Effects of physical interventions on house dust mite allergen levels in carpet, bed, and upholstery dust in low-income, urban homes.

House dust mite allergen exposure is a postulated risk factor for allergic sensitization, asthma development, and asthma morbidity; however, practical and effective methods to mitigate these allergens from low-income, urban home environments remain elusive. The purpose of this study was to assess the feasibility and effectiveness of physical interventions to mitigate house dust mite allergens in this setting. Homes with high levels of house dust mite allergen (Der f 1 + Der p 1 > or = 10 microg/g dust by enzyme-linked immunosorbent assay) in the bed, bedroom carpet, and/or upholstered furniture were enrolled in the study. Carpets and upholstered furniture were subjected to a single treatment of either dry steam cleaning plus vacuuming (carpet only) or intensive vacuuming alone. Bed interventions consisted of complete encasement of the mattress, box spring, and pillows plus either weekly professional or in-home laundering of nonencased bedding. Dust samples were collected at baseline and again at 3 days (carpet and upholstery only) and 2, 4, and 8 weeks posttreatment. We compared pretreatment mean allergen concentrations and loads to posttreatment values and performed between-group analyses after adjusting for differences in the pretreatment means. Both dry steam cleaning plus vacuuming and vacuuming alone resulted in a significant reduction in carpet house dust mite allergen concentration and load (p < 0.05). Levels approached pretreatment values by 4 weeks posttreatment in the intensive vacuuming group, whereas steam cleaning plus vacuuming effected a decrease that persisted for up to 8 weeks. Significant decreases in bed house dust mite allergen concentration and load were obtained in response to encasement and either professional or in-home laundering (p < 0.001). Between-group analysis revealed significantly less postintervention house dust mite allergen load in professionally laundered compared to home-laundered beds (p < 0.05). Intensive vacuuming and dry steam cleaning both caused a significant reduction in allergen concentration and load in upholstered furniture samples (p < 0.005). Based on these data, we conclude that physical interventions offer practical, effective means of reducing house dust mite allergen levels in low-income, urban home environments.

Allergens↗
PubMed1995

Evaluation of dust and dust mite nasal provocation.

BACKGROUND: The relevance of positive epicutaneous tests to dust mite in patients with perennial rhinitis is often not apparent clinically. OBJECTIVE: We attempted to assess and compare intranasal challenges with both dust and dust mite allergens in skin test positive patients with perennial symptoms. METHODS: Thirteen patients allergic to both dust and dust mite by prick testing were challenged intranasally with each allergen at 2-week intervals. Nasal provocation was performed stepwise to a maximum dose of 2,000 pnu (dust) and 500 pnu (mite). The control group was composed of seven symptomatic patients with negative skin tests. RESULTS: Control patients were uniformly clinically unresponsive to maximum dose. Allergic patients varied considerably in sensitivity but all reacted clinically to at least the final dose with an early response. There were no obvious late phase reactions. Both dust and mite provoked an early phase increase of eosinophil cationic protein in the nasal secretions of control patients. For allergic patients there were early increases of eosinophil cationic protein, prostaglandin D2 and leukotriene C4. Late phase elevations were not observed. CONCLUSION: Dust and mite skin test-positive patients with perennial rhinitis had similar early phase responses to intranasal challenge both clinically and with elevations of inflammatory mediators. Clinically unresponsive control patients did show elevated eosinophil cationic protein levels suggesting a possible nonspecific, non-IgE mediated affect of both dust and mite allergens on the nasal mucosa.

Adult↗
PubMed2002

House dust mites and their allergens at selected locations in the homes of house dust mite-allergic patients.

BACKGROUND: Knowledge of the occurrence of house dust mites (HDM) and their allergens in domestic locations is important when planning intervention. OBJECTIVE: The aim of this study was to describe the distribution of HDMs and their allergens before intervention in multiple locations in the homes of newly diagnosed HDM-allergic patients with a known high Der 1 concentration in their mattress dust. METHODS: Dust was collected from ten locations in the homes of eight HDM-allergic patients. Dust was analysed for allergen content with ELISAs for Der f 1, Der p 1 and Der m 1; and HDM were counted. Total allergen concentrations ( micro g Der 1/g dust) were expressed as the sum of Der f 1, Der p 1 and Der m 1. RESULTS: On mattresses the median concentration was 86 micro g Der 1/g dust (range 30-288) and 188 mites/g dust (range 12-1910). Der 1 exceeded 10 micro g/g dust in mattresses (8/8), duvets/pillows (3/8), a bedroom carpet (1/1), a living room carpet (1/6), upholstered furniture (2/8) and a curtain (1/5). Uncarpeted floors, upholstered furniture, bookshelves and walls had significantly lower Der 1 concentration than the mattresses. The relative contribution of Der p 1, Der f 1 or Der m 1 to Der 1 was related to homes, rather than to the location. Der m 1 only occurred in minute amounts. CONCLUSION: For HDM intervention, our results indicate that priority should be given to the removal of allergens from mattresses, and in addition from carpets, duvets/pillows and upholstered furniture. Dust from walls, uncarpeted floors, bookshelves and curtains appear to contribute insignificantly to the domestic HDM allergen load.

Animals↗
PubMed2003

Dust size distribution for dust acoustic waves in a magnetized dusty plasma.

A reasonable normalization for a magnetized dusty plasma with many different dust grains is adopted, which varies self-consistently with the system parameters. A Zakharov-Kuznetsov equation for small but finite amplitude dust acoustic waves is obtained for magnetized dusty plasma which contains different dust grains by using the reductive perturbation technique. We study the dust size distribution. Some comparisons are made between dusty plasma in which the dust size distribution is considered, and the monosized dusty plasma in which there is only one kind of dust grain whose size is the average dust size. This suggests that both soliton velocity and width are larger than that for monosized dusty plasma, but its amplitude is smaller than that for monosized dusty plasma. If there are positively charged dust grains, compressive solitary waves may exist. The velocity, amplitude, and width of a soliton in multidimensional form for a magnetized dusty plasma which contains many different dust grains are studied as well.

Journal Article↗
PubMed2004

Permeability of synthetic and feather pillows to live house dust mites and house dust.

BACKGROUND: Previous studies have demonstrated significantly higher house dust mite (HDM) allergen levels from synthetic pillows, compared to feather pillows. Reasons for these differences could be lower permeability of feather pillow coverings to allergen in dust, greater HDM penetration of synthetic pillow covering, or both. OBJECTIVES: To determine the permeability of synthetic and feather pillow coverings to live HDMs and house dust. METHODS: Twenty live adult HDMs were seeded on top of two types of synthetic pillow covering (one standard polyester and one newer polyester/cotton type) and one type of feather pillow coverings with adequate food supply below in sealed culture dishes, kept at 23 degrees C and 70% relative humidity. After 24 and 48 h live HDM numbers remaining on top of the coverings were enumerated microscopically. Three aliquots of fine house dust (each in triplicate) were placed on top of the synthetic and feather pillow coverings, shaken gently for 30 min and penetrated dust was collected and weighed. RESULTS: After 24 h, all 20 HDMs had penetrated the standard synthetic pillow coverings, and no HDMs had penetrated either the feather pillow or the new synthetic pillow coverings after 24 or 48 h. Dust permeability (% of applied dust) for the standard synthetic, new type synthetic and feather pillow coverings were 0.88%, 0.07%, and 0.07%, respectively. This compared to 0.02% for a commercial occlusive pillow cover. CONCLUSIONS: These findings of total permeability of standard synthetic pillow coverings to live HDMs, and their greater permeability to house dust could explain their reported higher HDM allergen levels, compared to feather pillow coverings. Newer types of synthetic pillow coverings are similar to feather pillow coverings in their permeability to live HDMs and house dust.

Allergens↗
PubMed1997

Measurement error and its impact on the estimated relationship between dust lead and children's blood lead: Members of the Rochester Lead-in-Dust Study Group.

OBJECTIVE: Lead-contaminated house dust is a major contributor to lead intake among urban children, but the reliabilities of various dust lead measurement methods and their impact on the estimated correlations between dust lead and children's blood lead levels are unknown. METHODS: Repeated field measurements of lead-contaminated dust from children's homes were taken from 16 housing units using five dust lead measurement methods. Estimates of measurement error were used to obtain reliability ratios for the dust lead measurements, which were then used to correct estimated correlations between lead-contaminated dust and children's blood lead. RESULTS: Reliability varied over methods and surface types (from 0.0 to 0.8), but wipe loading and the BRM vacuum loading methods generally had greater reliability. Technician effects, inadvertent field exposure to lead, contamination of collection equipment, and laboratory instrument error were found to contribute little to total measurement error. Corrected correlations between blood lead and wipe loading measurements were 7 to 104% higher than uncorrected correlations. The multiple R2 and partial R2 for a wipe composite measurement in a multivariate regression model increased from 0.43 to 0.64 and from 0.053 to 0.26, respectively, after correction for measurement error bias. CONCLUSIONS: Variation in lead deposition within small areas and variations in collection inherent to the devices are major contributors to measurement error. Measurement error causes dramatic underestimation of correlation between lead-contaminated house dust and children's blood lead.

Air Pollution, Indoor↗
PubMed1987

Children's blood lead and exposure to lead in household dust and water--a basis for an environmental standard for lead in dust.

Good quantitative evidence on the role of lead in household dust as a source of exposure to children has been lacking. A study of 495 children in Edinburgh, Scotland shows a significant relationship between lead in dust vacuumed from the floors of the children's homes and their blood lead levels. A multiple regression analysis incorporating drinking water and household dust estimates that a 1,000 micrograms g-1 increase in dust lead concentration would increase blood lead by 1.9 micrograms dl-1, for a child with the median population blood lead of 10.1 micrograms dl-1. Dust lead concentration is a more useful predictor of blood lead than lead loading. The sanding or blow-lamp stripping of old paint is found to be an important source of the higher household dust lead concentrations. Finally, the dust lead-blood lead relationship is used to derive a standard for lead in house dust, as no such standard exists for this exposure route.

Child↗
PubMed2003

Inhaled endotoxin and organic dust particulates have synergistic proinflammatory effects in equine heaves (organic dust-induced asthma).

BACKGROUND: Equine heaves is a naturally occurring organic dust-induced asthma characterized by airway neutrophilia, mucus hypersecretion and obstructive lung dysfunction. However, the relative role of different dust components in disease severity remains unclear. OBJECTIVE: This study investigated the relative contribution of inhaled endotoxin and organic dust particulates (mainly mould spores) in inducing heaves in heaves-susceptible horses. METHODS: Control and heaves-susceptible horses received inhalation challenges with hay dust suspension (HDS) before and after lipopolysaccharide (LPS) depletion. Heaves-susceptible horses also received inhalation challenge with HDS particulates with and without the addition of LPS and were housed in two separate dusty environments during which mould and endotoxin exposure was measured. The airway inflammatory and functional response to each challenge was measured. RESULTS: Depletion of endotoxin from HDS attenuated the airway neutrophilia and abrogated the airway dysfunction induced in heaves horses by inhaled HDS. The airway response was re-established by adding back LPS to the depleted HDS, confirming that the attenuation in airway response was due specifically to endotoxin depletion. Interestingly, the magnitude of alteration in airway response following endotoxin depletion and add-back was greater than that which could be attributed solely to endotoxin per se, indicating that the LPS activity was enhanced by the other dust components. Consistent with this possibility, washed particulates harvested from HDS enhanced the airway response to inhaled LPS in heaves horses. Heaves horses given two different hay/straw challenges had a significantly different severity of airway inflammation and dysfunction, despite airborne dust and endotoxin concentrations in the horses' breathing zones being similar. CONCLUSION: Although inhaled endotoxin appears not to be the only determinant of disease severity in heaves, it does contribute significantly to the induction of airway inflammation and dysfunction. This contribution is largely via the synergistic action of inhaled endotoxin and organic dust particulates, although other soluble dust components also contribute to a lesser degree.

Animals↗