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PubMed2004

Heating of indoor dust causes reduction in its ability to stimulate release of IL-8 and TNFalpha in vitro compared to non-heated dust.

UNLABELLED: Dust is a major contaminant of the indoor air environment and may affect human health. Indoor dust accumulates on surfaces including heaters and light fixtures, and will be heated when these devices are used. Heat treatment of the dust may change its biologic properties and in this study we simulated the heat treatment with a dust-heating model (50-250 degrees C). The residual and the non-heated dust from seven samples were tested in cultures of fresh peripheral blood mononuclear cells and in A549 cell culture using the release of TNFalpha and IL-8, respectively, as effect indicators. The endotoxin-content and the particle size distribution of the residual and the non-heated dust suspensions were determined for some of the samples. We found that the residual dust had less ability to induce the release of TNFalpha and IL-8. The cytokine decline pattern was similar for all the dust tested and could partly be explained by the reduction in endotoxin content or possibly by inhibitory decomposition products. No correlation was found between the measured particle size distribution and the decreased cytokine levels. The results in this study suggest that the residual dust promotes reduced cytokine response and thereby a possibly lower inflammation reaction in the airways if suspended and inhaled compared with the non-heated dust. PRACTICAL IMPLICATIONS: Accumulation of indoor dust on electric heaters and light fixtures may produce a bad odor when switched on in the cold season and some people claim respiratory distress during such events. To investigate to what extent the residuals of heated indoor dust represent a health hazard, we measured the effect in cell cultures before and after heat treatment of the dust. The in vitro results imply that the residual dust will cause a lower proinflammatory response in the airways if suspended and inhaled compared with non-heated dust. This is partly explained by heat destruction of inflammatory components in the dust.

Air Pollutants↗
PubMed1999

[Studies on appropriate methods for dust scrubbing from dust-laden gas in shaft kilns of small-sized cement plants].

OBJECTIVE: To study an appropriate method for dust scrubbing from dust-laden gas in the shaft kilns of small-sized cement plants. METHODS: Characteristics of dust-laden gas, including its temperature, dew point, dust concentration, diameters of dust particles and their distribution, as well as fractional dust collection efficiencies of the dust precipitator settling chamber, cyclone, impinging scrubber, impinging-spray scrubber, were measured according to the National Standards for Measurement of Particulate in Exhaust Gas Emitted from the Stationary Pollution Sources and Sampling Methods of Gaseous Pollutants (GB/T16157 - 1996), with a WY-1 In-stack 7-Stage Cascade Impactor for fractional dust collection. RESULTS: The fractional dust collection efficiency of the settling chamber for the particles greater than 12 microm was 72%, while that of the cyclone for the particles of 2 microm, 5 microm and 10 microm were 40.0%, 72.5% and 88.9%, respectively, and that of impinging scrubber was 55.0%, 91.0% and 98.9%, respectively; and that of impinging-spray scrubber were 96.0%, 99.2% and 99.6%, respectively. Results showed that 81% of the dust (by weight) from the shaft kilns were greater than 10 microm, so the settling chamber was effective for the removal of this fraction of dust. But dust particles behind the settling chamber were finer, and about 59% - 69% of them were less than 2 microm in diameters. In that case, the cyclone, impinging scrubber and impinging-spray scrubber could give an overall collection efficiency of 54%, 57% and 96%, respectively. Based on this, the following combination of dust collectors were adopted to meet the national standards for exhaust emission: a settling chamber plus an electrostatic precipitator, a settling chamber plus an impinging-spray scrubber and a settling chamber plus an impinging scrubber. The cement plants could select appropriate dust collectors according to their technical and economical conditions. CONCLUSION: Based on the results of the studies, appropriate dust collectors used to treat dust-laden gas from shaft kilns to meet the national standards for exhaust emission were recommended.

Air Pollutants, Occupational↗
PubMed1986

Dust exposure, dust recovered from the lung, and associated pathology in a group of British coalminers.

The relation between dust exposure, retained lung dust, and pneumoconiosis have been examined in 430 dead coalminers who had participated in a large scale epidemiological survey of respiratory health. The men were divided into three groups depending on the presence of particular lesions in their lungs. Lungs containing no fibrotic lesions in excess of 1 mm were included in the "M" group, those with fibrotic lesions of between 1 mm and 9 mm in diameter were included in the "F" group, and those with any lesion 10 mm or more were categorised as having progressive massive fibrosis (PMF). The men were further divided into four groups according to the rank of coal mined at the colliery of employment. The mean weight of lung dust increased over the pathological range (M----F----PMF) regardless of the rank of coal mined. The men with PMF had not received unusually high exposures to dust in life but were found to have accumulated more dust in their lungs per unit of dust exposure than men without PMF, providing further evidence for differences in the patterns of deposition or clearance, or both, of dust in these men compared with those who do not develop PMF. For men who had mined the higher rank coals there was no difference in the composition of the lung dust between the pathological groups. Lungs from men mining low rank coal, however, showed a striking increase in the proportion of ash over the pathological groups (M, F, and PMF). In men who had mined low rank coal the proportion of ash in the airborne dust to which they had been exposed and in the dust retained in their lungs was, as expected, greater than in men who had worked with higher rank coals. For the same men, and particularly associated with the presence of some dust related fibrosis, the proportion of ash in retained dust was higher than that in the dust to which the men were exposed suggesting the occurrence of selective deposition or retention of the mineral components of dust in this group.

Aged↗
PubMed1993

Relationship between dust mite allergen and human IgA in house dust samples.

Previous investigators have mentioned that human IgA is found in house dust. IgA has also been reported to be present on human skin and hence in human dander. If human dander is the primary source of food for house dust mites, a relationship would be expected between IgA and dust mite allergen (Der f I) concentrations. We wished to learn whether IgA was consistently detectable in house dust and whether IgA and dust mite allergen concentrations were related. Dust samples were collected from the bedrooms of infants enrolled in a prospective study designed to evaluate the relationship between early allergen exposure and childhood allergic disease. One hundred eighty samples were studied: 50 samples were the initial samples collected from the first 50 infants enrolled, 120 samples were monthly samples obtained from 10 other homes, and 10 additional samples were randomly selected for extraction in a nonprotein containing buffer to determine the percentage of total extractable dust protein contributed by IgA. Finally, nine commercial house dust extracts were studied to learn whether they were similar to the dust samples from study houses. Enzyme linked immunosorbent assays (ELISAs) were used to measure human IgA, human secretory IgA (sIgA) and Der f I concentrations in all of the dust extracts. We found that IgA was consistently present in house dust samples ranging from 3.2 to 2,396 micrograms of IgA per gram of dust. A strong correlation (r = .90) was found between IgA and sIgA concentrations. IgA constituted 0.27% to 6.04% of the total protein in dust samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollution↗
PubMed1986

Carbohydrate and protein contents of grain dusts in relation to dust morphology.

Grain dusts contain a variety of materials which are potentially hazardous to the health of workers in the grain industry. Because the characterization of grain dusts is incomplete, we are defining the botanical, chemical, and microbial contents of several grain dusts collected from grain elevators in the Duluth-Superior regions of the U.S. Here, we report certain of the carbohydrate and protein contents of dusts in relation to dust morphology. Examination of the gross morphologies of the dusts revealed that, except for corn, each dust contained either husk or pericarp (seed coat in the case of flax) fragments in addition to respirable particles. When viewed with the light microscope, the fragments appeared as elongated, pointed structures. The possibility that certain of the fragments within corn, settled, and spring wheat were derived from cell walls was suggested by the detection of pentoses following colorimetric assay of neutralized 2 N trifluoroacetic acid hydrolyzates of these dusts. The presence of pentoses together with the occurrence of proteins within water washings of grain dusts suggests that glycoproteins may be present within the dusts. With scanning electron microscopy, each dust was found to consist of a distinct assortment of particles in addition to respirable particles. Small husk fragments and "trichome-like" objects were common to all but corn dust.

Amino Acids↗
PubMed1991

[Does the average dust concentration modify the critical dust dose leading to silicosis?].

This article is based on the established fact that there is a relationship between the probability of the occurrence of silicosis and the inhaled amount of dust, the latter being represented by the concept of "dust dose" which is a product of dust concentration multiplied by the period of exposure. On investigating the "dust dose" values in 179 former coal miners in the East German town of Zwickau, however, we found that the "dust dose" principle does not apply to low to medium dust concentrations. We can now outline our idea of the origin and development of silicosis as follows: Below an initial threshold value of the "dust dose" it is improbable that silicosis will develop. Beyond that value, i.e. at medium dust concentrations, the time that elapses between the beginning of exposure and the onset of the disease is constant, namely, 20 years. However, the "dust dose" values that trigger the disease vary greatly. For dust concentrations beyond a second threshold value matters are as originally expected: the dust dose being constant, the disease will set in the earlier, the higher the dust concentration. To visualize these effects, a smoothing mathematical evaluation method was combined with a variant of the t test.

Adult↗
PubMed1999

Reducing dust, lead, dust mites, bacteria, and fungi in carpets by vacuuming

Old carpets may be reservoirs of dust, lead (Pb), and dust mite allergen. The purpose of this study was to determine if the dust, Pb, dust mite allergen, bacteria, and fungi on the surface of carpets could be reduced by 90% in 1 week with the use of a Hoover Self Propelled Vacuum with Embedded Dirt Finder (HSPF). A high-volume surface sampler (HVS3) was used to measure surface dust and pollutants before and after the use of the HSPF to remove deep dust in carpets 12 to 20 years old in nine middle-class homes and two small offices. The minimum, median, and maximum surface loading for the first and final samples are as follows: first fine dust loading: min 0.32 g/m2, max 14.4 g/m2, median 1.30 g/m2; final fine dust loading: min 0.019 g/m2, max 0.289 g/m2, median 0.102 g/m2; first Pb loading: min 38 &mgr;g/m2, max 3,871 &mgr;g/m2, median 471 &mgr;g/m2; final Pb loading: min 13 &mgr;g/m2, max 2,023 &mgr;g/m2, median 86 &mgr;g/m2; first mite loading: min 0.11 &mgr;g/m2, max 12. 88 &mgr;g/m2, median 2.82 &mgr;g/m2; final mite loading: min 0.06 &mgr;g/m2, max 3.67 &mgr;g/m2, median 0.28 &mgr;g/m2. Data were insufficient to determine if the loadings of bacteria and fungi were reduced a similar amount. Six to 45 min/m2 of vacuuming with the HSPF removed deep dust from these carpets. The median surface loadings of fine dust, Pb, and dust mite allergen in these 11 carpets were reduced by 91, 82, and 94%, respectively, in 1 to 15 h of vacuuming. The loading of the deep dust collected with the HSPF ranged from 8 to 171 g/m2 with a median of 66 g/m2.

Journal Article↗
PubMed1985

Evolution of efficient methods to sample lead sources, such as house dust and hand dust, in the homes of children.

Efficient sampling methods to recover lead-containing house dust and hand dust have been evolved so that sufficient lead is collected for analysis, and to ensure that correlational analyses linking these two parameters to blood lead are not dependent on the efficiency of sampling. Precise collection of loose house dust from a 1-unit area (484 cm2) with a Tygon or stainless steel sampling tube connected to a portable sampling pump (1.2 to 2.5 liters/min) required repetitive sampling (three times). The Tygon tube sampling technique for loose house dust less than 177 microns in diameter was around 72% efficient with respect to dust weight and lead collection. A representative house dust contained 81% of its total weight in this fraction. A single handwipe for applied loose hand dust was not acceptably efficient or precise, and at least three wipes were necessary to achieve recoveries of greater than 80% of the lead applied. House dusts of different particle sizes less than 246 microns adhered equally well to hands. Analysis of lead-containing material usually required at least three digestions/decantations using hot plate or microwave techniques to allow at least 90% of the lead to be recovered. It was recommended that other investigators validate their handwiping, house dust sampling, and digestion techniques to facilitate comparison of results across studies. The final methodology for the Cincinnati longitudinal study was three sampling passes for surface dust using a stainless steel sampling tube; three microwave digestions/decantations for analysis of dust and paint; and three wipes with handwipes with one digestion/decantation for the analysis of six handwipes together.

Adult↗
PubMed1986

Cross-reacting and species-specific determinants on a major allergen from Dermatophagoides pteronyssinus and D. farinae: development of a radioimmunoassay for antigen P1 equivalent in house dust and dust mite extracts.

Two species of mites of the genus Dermatophagoides are common in house dust and make a major contribution to the allergen content of house dust. As judged by skin tests and the radioallergosorbent test, these mites, D. pteronyssinus and D. farinae, demonstrate extensive cross-reactivity. When the major allergen from D. pteronyssinus, antigen P1, was compared with the equivalent allergen from D. farinae, these two proteins were found to have both species-specific and common antigenic determinants. With specifically purified antibodies directed against the common determinants, we developed a radioimmunoassay for these antigen P1 equivalent proteins in mite extracts as well as house dust extracts. The quantity of allergen in dust from 63 houses (255 samples) was measured, and values ranged from less than 100 to greater than 100,000 ng/gm of fine dust. The correlation between antigen P1 equivalent (ng/gm) and the number of mites per gram of dust (identified by microscopy) was very good (r = 0.74; p less than 0.001). Furthermore, this correlation was not affected by the species of mite in the dust sample. Of 9243 mites identified, 95% were of the genus Dermatophagoides, and of these, 16.4% and 18% could be positively identified as D. farinae and D. pteronyssinus, respectively. When the assay for antigen P1 equivalent was applied to isolated components of mite cultures of both species, significant allergen was found in the mite bodies, cuticles, and their excreta (fecal particles). For the house-dust samples, less than 10% of the allergen measured could be explained by the allergen content of mite bodies. Our results demonstrate that a radioimmunoassay for antigen P1 equivalent can provide an accurate and simple means of assessing the quantity of mite-derived allergen in dust-mite extracts, house-dust extracts, or house dust.

Allergens↗
PubMed1987

Seasonal variation in dust mite and grass-pollen allergens in dust from the houses of patients with asthma.

In order to study seasonal variation in dust-mite allergen, we obtained dust samples from bedding, carpet, and/or sofas in 12 houses in central Virginia, monthly, for 1 year. The houses included those of nine patients with asthma of whom six were allergic to dust mites. Dust samples were assayed with an inhibition radioimmunoassay for mite allergen that detects cross-reacting determinants on Der f and Der p I from Dermatophagoides farinae and D. pteronyssinus, respectively. The results are expressed as micrograms of antigen P1 equivalent (AgP1Eq). The results demonstrate that large seasonal variations in allergen, i.e., more than twentyfold, can occur in dust from all sites and are not restricted to the houses of allergic patients. However, dust from some sites, particularly sofas, remained "high" (greater than 10 micrograms AgP1Eq per gram), whereas dust from other sites remained "low" (less than 1 microgram AgP1Eq per gram) throughout the year. Levels of mite allergen generally started to rise in July about 1 month after the rise in humidity. In August to December, the mean levels of AgP1Eq in house dust were highly significantly increased relative to April to May. In keeping with this finding, in 31 of 37 sites, the highest level for the year was observed in August through December. In four sites, mite bodies were counted, and the numbers increased sharply in June to July; however, they decreased in September in parallel with falls in humidity but several months before the fall in mite allergen. Ryegrass-pollen allergen in 12 sites was also assayed in house dust, and pollen-allergen levels demonstrated a sharp increase in May or June that fell back to preseason values within 2 months. Dust was also obtained from the houses of 50 patients with acute or severe asthma. The results on these samples suggest that mite-allergic patients are more likely to have attacks in the fall at a time when their houses have greater than 10 micrograms AgP1Eq per gram of dust. The magnitude of changes observed seasonally within individual houses and of differences between houses within a close geographic area suggests that interpretation of the relationship between allergic symptoms and mite-allergen exposure will require measurement of mite-allergen levels in individual houses.

Asthma↗
PubMed1995

House dust mite allergen levels in dust from schools with smooth and carpeted classroom floors.

A study was conducted to investigate the levels of house dust mite allergen Der p I in classroom floor dust from 49 schools with smooth (n = 18) or carpeted (n = 31) floors. Schools were located in the city of Rotterdam (n = 29) and in a number of small communities in the Province of Gelderland (n = 20). Data on building characteristics of the schools were obtained. Dust samples were analysed for Der p I content, the major allergen of the house dust mite Dermatophagoides pteronyssinus. The results showed that in schools with carpeted classroom floors, larger amounts of settled dust and higher Der p I levels either expressed as concentrations (in ng/g) or loadings (in ng/m2) were found than in schools with smooth classroom floors. However, the levels of Der p I were considerably lower than in dust collected from floors in homes. Although the Der p I levels were low, effects of several building characteristics on the levels were found. Age of the floor cover, the number of classrooms in the school and the presence of damp spots in the building were related to Der p I concentrations and loadings mainly on carpeted floors. Remarkably, schools in the rural area contained significantly more dust and Der p I than schools in the urban area. We conclude that dust from carpeted classroom floors contains more house dust mite allergen than dust from smooth classroom floors, but much less than dust from floors in homes.

Adolescent↗
PubMed2004

The clinical effect of environmental control of house dust mites in 60 house dust mite-sensitive dogs.

The purpose of this study was to evaluate the effects of benzyl benzoate, an acaricide for the control of house dust mites, in 60 house dust mite-sensitive dogs. All dogs showed positive reactions on intradermal skin testing for house dust mites (Dermatophagoides farinae, Dermatophagoides pteronyssinus) alone, or house dust mites with storage mites (Acarus siro, Tyrophagus putrescentiae, Glycophagus domesticus). House dust samples from the owners' houses were collected and sent to the clinic, where the authors performed a test (Acarex test) to semi-quantify the amount of guanine, a house dust mite product. Treatment with benzyl benzoate was repeated until the house dust samples were negative for house dust mite guanine. After treatment, 29 out of 60 house dust mite-sensitive dogs (48%) showed no skin lesions or pruritus. Moderate results were achieved in 22 dogs (36%), with reduced pruritus and minimal skin lesions, but still requiring medication. In 13 dogs, this involved regular treatment (3-4 times a year) with antibiotics and anti-yeast medication, and in eight dogs, immunotherapy was used. One dog was controlled with essential fatty acids as monotherapy and one dog was controlled with immunotherapy and essential fatty acids. In the remaining nine dogs (15%), the pruritus remained the same, and these dogs were controlled with oral corticosteroids. These results indicate that house dust mite elimination is a useful tool in the management of house dust mite-sensitive dogs.

Animals↗
PubMed2003

A study of urban housing demolitions as sources of lead in ambient dust: demolition practices and exterior dust fall.

Demolition of older housing for urban redevelopment purposes benefits communities by removing housing with lead paint and dust hazards and by creating spaces for lead paint-free housing and other community resources. This study was conducted to assess changes, if any, in ambient dust lead levels associated with demolition of blocks of older lead-containing row houses in Baltimore, Maryland (USA). In this article we present results based on dust-fall samples collected from fixed locations within 10 m of three demolition sites. In subsequent reports we will describe dust lead changes on streets, sidewalks, and residential floors within 100 m of the demolition sites. Geometric mean (GM) lead dust-fall rate increased by > 40-fold during demolition to 410 micro g Pb/m2/hr (2,700 micro g Pb/m2 per typical work day) and by > 6-fold during debris removal to 61 micro g Pb/m2/hr (440 micro g Pb/m2 per typical work day). Lead concentrations in dust fall also increased during demolition (GM, 2,600 mg/kg) and debris removal (GM, 1,500 mg/kg) compared with baseline (GM, 950 mg/kg). In the absence of dust-fall standards, the results were compared with the U.S. Environmental Protection Agency's (U.S. EPA's) dust-lead surface loading standard for interior residential floors (40 micro g/ft2, equivalent to 431 micro g/m2); daily lead dust fall during demolition exceeded the U.S. EPA floor standard by 6-fold on average and as much as 81-fold on an individual sample basis. Dust fall is of public health concern because it settles on surfaces and becomes a pathway of ambient lead exposure and a potential pathway of residential exposure via tracking and blowing of exterior dust. The findings highlight the need to minimize demolition lead deposition and to educate urban planners, contractors, health agencies, and the public about lead and other community concerns so that society can maximize the benefits of future demolition activities nationwide.

Baltimore↗
PubMed2000

Reactivity to intradermal injection of extracts of Dermatophagoides farinae, Dermatophagoides pteronyssinus, house dust mite mix, and house dust in dogs suspected to have atopic dermatitis: 115 cases (1996-1998).

OBJECTIVE: To compare reactivities to intradermal injection of extracts of Dermatophagoides farinae, Dermatophagoides pteronyssinus, house dust mite mix, and house dust in dogs suspected to have atopic dermatitis. DESIGN: Retrospective study. ANIMALS: 115 dogs. PROCEDURES: Records of all dogs suspected to have atopic dermatitis that underwent intradermal testing between October 1996 and July 1998 were reviewed. Reactivities to intradermal injection of crude mixed house dust mite (1:25,000 wt/vol) and crude house dust (25 PNU/ml) extracts were compared with reactivities to intradermal injection of individual extracts of D farinae and D pteronyssinus (1:50,000 wt/vol). RESULTS: Ninety dogs were confirmed to have atopic dermatitis including 61 of the 69 dogs with positive reactions to either or both of the individual house dust mite extracts. Intradermal testing with the mixed house dust mite extract had sensitivity of 75%, specificity of 96%, and accuracy of 83%. Intradermal testing with the house dust extract had sensitivity of 30%, specificity of 93%, and accuracy of 56%. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that use of crude mixed house dust mite and crude house dust extracts for intradermal testing in dogs is not as accurate a method of determining house dust mite hypersensitivity as is the use of individual D farinae and D pteronyssinus extracts mainly because of the high percentage of false-negative results. Extracts of individual house dust mites are recommended for intradermal testing of dogs suspected to have atopic dermatitis.

Allergens↗
PubMed2003

Exposure to dust and its particle size distribution in shoe manufacture and repair workplaces measured with GRIMM laser dust monitor.

OBJECTIVES: Owing to a diversified technological process and a great variety of products and materials used in shoe manufacture, workers may be exposed to dusts that contain different chemicals and particles of various shapes and sizes. The aim of this study was to assess the dust exposure, taking account of concentration of particular size fractions according to the European Standard Norm, and to analyze particle size distribution in inhalable dust at selected workplaces in a modern shoe manufacture plant and in a small shoe repair workshop in comparison with other industrial branches. MATERIALS AND METHODS: In these two workplaces, the concentrations of dust, representing the inhalable, thoracic, and respirable fractions, were measured with the GRIMM 1.105 laser dust monitor. RESULTS: The particle size distribution in inhaled dust in the most characteristic workposts was analyzed. In the shoe manufacture plant, the concentrations ranged from 124 microg/m3 (leather cutting out) to 724 microg/m3 (scouring and milling of soles); concentrations of the thoracic and respirable fractions in the same workposts ranged from 74 microg/m3 to 412 microg/m3 and from 24 microg/m3 to 120 microg/m3, respectively. In the shoe repair workshop, the recorded concentrations were higher: the values ranged from 521 microg/m3 (gluing of shoes and soles, zipper exchange and heel abrasion) to 916 microg/m3 (uppers sewing and heel scouring) for the inhaled fraction; from 335 microg/m3 to 499 microg/m3 for the thoracic fraction; and from 88 microg/m3 to 120 microg/m3 for the respirable fraction. The mass median aerodynamic diameters of inhalable dust particles fell within the limits of 6.2-25.0 mm. Dust with the smallest particles (MMAD = 6.2 mm) was observed in shoe brushing and polishing, and with the largest particles (MMAD = 25.0 mm) in uppers sewing. CONCLUSIONS: The modern process of shoe manufacture is characterized by very low concentrations of inhalable dust and its fractions, they are considerably lower than occupational exposure limits in Poland for inhaled (4000 microg/m3) and respirable (2000 microg/m3) dust. In the workplaces under study, a relatively high proportion of extrathoracic fraction of leather dust was found, which supports a hypothesis on a potential etiologic role of this factor in the development of pathologies in the upper airways region.

Air Pollutants, Occupational↗
PubMed1999

Long-range transport of mineral dust in the global atmosphere: impact of African dust on the environment of the southeastern United States.

Soil dust is a major constituent of airborne particles in the global atmosphere. Dust plumes frequently cover huge areas of the earth; they are one of the most prominent and commonly visible features in satellite imagery. Dust is believed to play a role in many biogeochemical processes, but the importance of dust in these processes is not well understood because of the dearth of information about the global distribution of dust and its physical, chemical, and mineralogical properties. This paper describes some features of the large-scale distribution of dust and identifies some of the geological characteristics of important source areas. The transport of dust from North Africa is presented as an example of possible long-range dust effects, and the impact of African dust on environmental processes in the western North Atlantic and the southeastern United States is assessed. Dust transported over long distances usually has a mass median diameter <10 microm. Small wind-borne soil particles show signs of extensive weathering; consequently, the physical and chemical properties of the particles will greatly depend on the weathering history in the source region and on the subsequent modifications that occur during transit in the atmosphere (typically a period of a week or more). To fully understand the role of dust in the environment and in human health, mineralogists will have to work closely with scientists in other disciplines to characterize the properties of mineral particles as an ensemble and as individual particles especially with regard to surface characteristics.

Journal Article↗
PubMed1995

A side-by-side comparison of dust collection methods for sampling lead-contaminated house dust.

The Environmental Protection Agency is required to set a standard for lead-contaminated house dust, but whether dust lead loading (micrograms/ft2) or concentration (micrograms/g) is more predictive of children's blood lead levels, which dust collection method should be used, and which surfaces should be sampled are unknown. Using a random sample of sequential births, we enrolled 205 urban children, 12 to 30 months of age, who had lived in the same house since at least 6 months of age. Samples of dust were obtained from predetermined surfaces in each child's residence using a wipe method and two vacuum methods, the Baltimore repair and maintenance method (BRM) and the dust vacuum method (DVM). Other potential sources of environmental exposure also were analyzed for lead, including soil, water, and paint. In general, dust lead loading is more predictive of children's blood lead levels than is dust lead concentration. Dust lead loading as measured with the BRM sampler explained more of the variation in children's blood lead levels than did wipe loading and DVM loading (13.7, 10.1, and 5.9%, respectively, adjusted for other significant predictors). The partial correlation between BRM lead loading and children's blood lead was significantly different than that for DVM lead loading, but it was not significantly different than that for wipe lead loading. Of the four surfaces measured, noncarpeted floors and interior window sills or wells were significantly associated with children's blood lead levels in multiple regression models. These data indicate that dust lead loading is more predictive of children's blood lead levels than is dust lead concentration and that, to determine if a housing unit is safe for children, noncarpeted floors and interior window sills or window wells should be measured using either the BRM or wipe sampling method.

Air Pollution, Indoor↗