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PubMed2001

A multi-element profile of housedust in relation to exterior dust and soils in the city of Ottawa, Canada.

This paper presents multi-element profiles of indoor dust versus exterior soils and dusts from 50 residences located in 10 neighborhoods across Ottawa, the capital city of Canada. Mercury concentrations were determined using nitric-sulphuric acid digestion and cold vapor AAS. Concentrations of 31 other elements were determined using nitric-hydrofluoric acid digestion and ICP-MS. Comparisons of household dust, garden soil and street dust at the individual residence scale and at the community scale were based on a consistent 100-250-microm particle size fraction. Results showed housedust samples to contain significantly higher concentrations of many key elements, including lead, cadmium, antimony and mercury, than either street dust or garden soil samples. Also, housedust profiles revealed a distinct multi-element signature in relation to exterior dust and soil samples. Interestingly, garden soil contained higher concentrations of aluminum, barium and thallium than either house or street dust. Geometric mean concentrations (mg/kg) of these elements in household dust/garden soil were: lead 233/42; cadmium 4.42/0.27; antimony 5.54/0.25; mercury 1.728/0.055; aluminum 24281/55677; barium 454/763; and thallium 0.14/0.29. Street dust contained lower geometric mean concentrations than garden soil for 23 out of a total of 32 elements. In general, indoor/outdoor concentration ratios varied widely from one element to another, and from one residence to another within the community. In the case of Ottawa, which is a city with a low concentration of heavy industries, it would be difficult-to-impossible to accurately predict indoor dust concentrations based on exterior soil data. It is concluded that dust generated from sources within the house itself can contribute significantly to exposures to certain elements, such as lead, cadmium, antimony and mercury.

Canada↗
PubMed1999

Fungal extracellular polysaccharides in house dust as a marker for exposure to fungi: relations with culturable fungi, reported home dampness, and respiratory symptoms.

BACKGROUND: Epidemiologic studies have demonstrated an association between indoor fungal growth and respiratory symptoms. However, in only a few studies was fungal exposure actually measured. OBJECTIVE: The purpose of this study was to evaluate the measurement by enzyme immunoassay of extracellular polysaccharides of Aspergillus and Penicillium species (EPS-Asp/Pen ) in house dust as a marker for fungal exposure and to study the relations between EPS-Asp/Pen levels and home dampness and respiratory symptoms in children. METHODS: Extracts of house dust samples from bedroom and living room floors and mattresses from homes of 31 children with chronic respiratory symptoms and 29 children with no chronic respiratory symptoms were analyzed for EPS-Asp/Pen. RESULTS: EPS-Asp/Pen were readily detectable (40 to 46,513 nanogram equivalent/g dust) in 161 house dust extracts, with highest concentrations in living room floor dust. EPS-Asp/Pen levels were 2 to 3 times higher on carpeted floors than on smooth floors. EPS-Asp/Pen were significantly correlated with total culturable fungi (r = 0.3 to 0.5) and with house dust mite allergens (r = 0.3 to 0.5). EPS-Asp/Pen levels in living room floor dust were positively associated with occupant-reported home dampness. This was not observed for EPS-Asp/Pen in bedroom floor and mattress dust. EPS-Asp/Pen levels in living room floor dust were positively associated with respiratory symptoms. EPS-Asp/Pen in bedroom floor and mattress dust showed a reversed association with respiratory symptoms, possibly because of allergen-avoidance measures taken in the bedroom. CONCLUSION: The enzyme immunoassay for fungal EPS-Asp/Pen may be a useful method for exposure assessment of indoor fungi.

Antigens, Fungal↗
PubMed2001

Comparison of two floor mat lead dust collection methods and their application in pre-1950 and new urban houses.

This study investigated commercial floor mats as an alternative method to assess lead in residential dust in inner-city houses. Mats were placed for 3 weeks in interior entry-ways of 34 row houses built before 1950 and 17 new row houses in Baltimore City. A high volume sampler (an HVS3 floor model cyclone-based vacuum) and a hand-held portable cyclone sampler were used in the laboratory to collect side-by-side samples of mat dust. Both devices yielded comparable estimates of lead dust deposition, dust lead concentration, and dust deposition on field mat samples and had similar sampling efficiencies on mats spiked with various types of standard reference materials. The older houses had significantly higher daily lead dust deposition (mean = 130 micrograms/ft2/day by HVS3) than the newer houses (mean = 9 micrograms/ft2/day by HVS3), due to higher dust lead concentrations (mean = 1149 ppm vs mean = 107 ppm by HVS3) and not to differences in daily dust deposition (mean = 118 mg/ft2/day vs mean = 87 mg/ft2/day by HVS3) [corrected]. Mats were found to be a feasible method for the collection of dust that has accumulated for a known amount of time. Current wipe and vacuum methods do not allow for the estimation of dust deposition rates. Further research is needed to understand the role of floor mats as a risk assessment tool.

Air Pollution, Indoor↗
PubMed2005

Perfluorinated sulfonamides in indoor and outdoor air and indoor dust: occurrence, partitioning, and human exposure.

Perfluorinated alkyl sulfonamides (PFASs) which are used in a variety of consumer products for surface protection were investigated through a comprehensive survey of indoor air, house dust, and outdoor air in the city of Ottawa, Canada. This study revealed new information regarding the occurrence and indoor air source strength of several PFASs including N-methylperfluorooctane sulfonamidoethanol (MeFOSE), N-ethylperfluorooctane sulfonamidoethanol (EtFOSE), N-ethylperfluorooctane sulfonamide (EtFOSA), and N-methylperfluorooctane sulfonamidethylacrylate (MeFOSEA). Passive air samplers consisting of polyurethane foam disks were calibrated and used to conduct the indoor and outdoor survey. Indoor air concentrations for MeFOSE and EtFOSE (1490 and 740 pg m(-3), respectively) were about 10-20 times greater than outdoor concentrations, establishing indoor air as an important source to the outside environment. EtFOSA and MeFOSEA concentrations were lower in indoor air (40 and 29 pg m(-3) respectively) and below detection in outdoor air samples. For indoor dust, highest concentrations were recorded for MeFOSE and EtFOSE with geometric mean concentrations of 110 and 120 ng g(-1), while concentrations for EtFOSA and MeFOSEA were below detection and 7.9 ng g(-1) respectively. MeFOSE and EtFOSE concentrations in house dust followed levels in indoor air. However, resolution of the coupled air and dust data (for the same homes) was not successful using existing KoA-based models for surface-air exchange. The partitioning to house dust was greatly underpredicted. The difficulties with existing models may be due to the high activity coefficient of PFASs in octanol and/or a situation where the dust is greatly oversaturated with respect to the air due to components of the dust being contaminated with PFASs. A human exposure assessment based on median air and dust concentrations revealed that human exposure through inhalation (100% absorption assumed) and dust ingestion were approximately 40 and approximately 20 ng d(-1), respectively. However, for children the dust ingestion pathway was dominant and accounted for approximately 44 ng d(-1).

Air Pollutants↗
PubMed2001

Ochratoxin A in airborne dust and fungal conidia.

Farm workers are often exposed to high concentrations of airborne organic dust and fungal conidia, especially when working with plant materials. The purpose of this investigation was to study the possibility of exposure to the mycotoxin ochratoxin A (OTA) through inhalation of organic dust and conidia. Dust and aerosol samples were collected from three local cowsheds. Aerosol samples for determination of total conidia and dust concentrations were collected by stationary sampling on polycarbonate filters. Total dust was analysed by gravimetry, and conidia were counted using scanning electron microscopy. A method was developed for extraction and determination of OTA in small samples of settled dust. OTA was extracted with a mixture of methanol, chloroform, HCl, and water, purified on immunoaffinity column, and analysed by ion-pair HPLC with fluorescence detection. Recovery of OTA from spiked dust samples (0.9-1.0 microg/kg) was 74% (quantitation limit 0.150 microg/kg). OTA was found in 6 out of 14 settled dust samples (0.2-70 microg/kg). The total concentration of airborne conidia ranged from < 1.1 x 10(4) to 3.9 x 15(5) per m3, and the airborne dust concentration ranged from 0.08 to 0.21 mg/m3. Conidia collected from cultures of Penicillium verrucosum and Aspergillus ochraceus contained 0.4-0.7 and 0.02-0.06 pg OTA per conidium, respectively. Testing of conidial extracts from these fungi in a Bacillus subtilis bioassay indicated the presence of toxic compounds in addition to OTA. The results show that airborne dust and fungal conidia can be sources of OTA. Peak exposures to airborne OTA may be significant, e.g., in agricultural environments.

Agriculture↗
PubMed2001

Determination of gallic acid in wood dust as an indicator of oak content.

A high-performance liquid chromatography (HPLC) method was developed for the detection of extracted gallic acid in wood dust. Gallic acid is a polyphenol present in carcinogenic oak wood dust, but not in beech, ash, pine or spruce dusts, as confirmed by HPLC analyses. The method involved the extraction of gallic acid from the oak dust, followed by liquid chromatographic analysis. The correlation coefficient for the share of oak dust vs. the gallic acid concentration of wood dust was 0.995. The method was tested with oak wood dust samples collected on polycarbonate membrane filters during an 8 h workshift in a floor board factory, where the dust content of the air samples was determined gravimetrically. The oak dust and the gallic acid concentrations varied from 0.2 to 13.8 mg m-3 and from 0.03 to 3.8 micrograms m-3, respectively. These parameters were linearly correlated with a correlation coefficient of 0.95. The airborne gallic acid determination is a useful technique to confirm occupational exposure to oak wood dust, a recognized human carcinogen.

Carcinogens↗
PubMed1989

Chemical evolution of interstellar dust, comets and the origins of life.

It now appears that the chemical evolution of the pre-solar system interstellar dust ensures that a major fraction of comets is in the form of complex organic molecules at least partially of a prebiotic nature and that the submicron interstellar dust preserves its chemical integrity as result of forming a very tenuous low density comet structure whose solid matter occupies approximately 1/5 of the total volume. This low density micro structure further provides a physical basis for comets bringing a significant fraction of the original interstellar organic molecules to the earth unmodified by the impact event. Finally, the evidence for a large number of comet collisions with the early earth ensured that the major organic molecular budget on the earth's surface was "continuously" supplied along with water well before 3.8 billion years ago which is the earliest date for life. The chemistry and morphological structure of a comet nucleus as an aggregate of interstellar dust is used to provide comparisons with a variety of comet Halley results: the density of the nucleus and of the dust; the dust cloud model and its consequences on the production of C+ and CN in the coma by small organic grains; the surface albedo and the low nucleus heat conductivity and high surface temperature; the appearance of 10(-14) g and 10(-17) g dust particles along with higher masses; the mass spectra of dust and infrared spectroscopy as evidence for complex organic grain mantles and of very small (approximately 0.01 micrometer) carbonaceous and silicate grains; the appearance of small grains resulting from breakup of larger grains. The cosmic ray dosage of a comet nucleus during its 4.5 billion years in the Oort cloud appears to be many orders of magnitude less than the dosage of the preaggregated interstellar dust by ultraviolet photons except perhaps in the outer few meters of the nucleus of a new comet. The heat conductivity calculated for aggregated dust is certainly less than 10(-4) that of crystalline ice. This, in combination with the interstellar dust microstructure, provide a basis for showing that solar heating of the interior of a nucleus is lower than previously estimated.

Carbon↗
PubMed2003

Effects by 8-bromo-cyclicAMP on basal and organic dust-induced release of interleukin-6 and interleukin-8 in A549 human airway epithelial cells.

Inhalation of organic dust from a swine-confinement building leads to an intense inflammatory reaction with an increased number of inflammatory cells and mediators in the upper and lower respiratory tract of previously unexposed subjects. In vitro the dust induces cytokine release from epithelial cells and alveolar macrophages. It is known that intracellular cyclic AMP (cAMP) contributes to the regulation of inflammatory responses. We therefore investigated whether 8-Bromo-cAMP, a cell membrane-permeable cAMP analogue, would influence release of the cytokines interleukin-6 (IL-6) and IL-8 in a human airway epithelial cell line, A549, exposed to a suspension of the organic dust, and to a supernatant prepared by centrifugation (at low g-force) of a suspension of dust. The large particulate matter was thus sedimented, leaving bacteria, whole and cell wall constituents in the supernatant. Cytokine release was measured with enzyme-linked immunosorbent assay (ELISA). The cytokine release induced by a supernatant was 23% (IL-6) and 27% (IL-8) of the release induced by a dust suspension. 8-Bromo-cAMP (1 mM) doubled basal IL-6 release and IL-6 release induced by a dust supernatant (P<0.01), and increased IL-6 release induced by a dust suspension by 19% (P<0.05). 8-Bromo-cAMP did not affect basal IL-8 release, partially inhibited (28%) the release of IL-8 induced by a dust suspension (P<0.01), but increased IL-8 release induced by a dust supernatant by 13% (P<0.05). In summary, expression of the cytokines IL-6 and IL-8 is differentially regulated by 8-Bromo-cAMP, both with regard to basal and dust-induced release. The results indicate that 8-Bromo-cAMP attenuated IL-8 release by affecting signaling transductions induced by the particulate fraction.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2000

Personal sampling in parallel with open-face filter cassettes and IOM samplers for inhalable dust--implications for occupational exposure limits.

Parallel personal sampling was carried out with the open-face filter cassette and the IOM sampler for inhalable dust for nine types of organic dust. Parallel samples numbering 749 were obtained from 152 plants. Extremely large values and outliers were disregarded, and the remaining data for each type of dust were divided into subsets according to type of product or work task, and analyzed with the aid of linear regression. The coefficient of regression for each subset ranged between 0.2 and 0.7. Hypothetical occupational exposure limits (OELs) for inhalable dust were calculated based on the linear relation obtained between the dust concentrations measured with the open-face filter cassette and the IOM sampler. The fraction of person days with time-weighted average (TWA) concentrations exceeding the calculated hypothetical OELs for inhalable dust was obtained from the distribution of measured TWA inhalable dust concentrations. Based on the results of this study and the difference in sampling efficiency for large particles between the two samplers, it was concluded that the numerical value of the OEL for inhalable dust may be set at approximately twice the numerical value of the corresponding limit value for "total dust." Additional consideration of recently discovered health effects, and technical and economical factors may result in other numerical values of future OELs for inhalable dust.

Air Pollutants, Occupational↗
PubMed2002

Occupational exposure to cotton dust in cottonseed oil mills.

Air samples were collected at breathing height in the hulling-separation department of a modern cottonseed oil mill in Uzbekistan. The average elutriated mass concentration measured by standard cotton dust samplers was 4.6 mg/m3, much lower than the average total dust concentration measured by stationary personal samplers, 12.49 mg/m3, and by personal samplers attached to workers, 14.53 mg/m3. Differences in readings among the vertical elutriators, stationary personal samplers, and roving personal samplers are attributed to the distinct sampling nature and dynamics of these samplers. The data suggest that most of the dust consisted of particles larger than 15 microm, the particle size cutoff of the vertical elutriator. Differences in readings among stationary and roving personal samplers are statistically significant, presumably representing biased sampling by the roving personal samplers of regions characterized by high dust concentration (due to machines malfunctioning), the nonstatic nature of the sampling, and the interaction between the sampler and the worker (the personal cloud). Cotton dust concentrations in the hulling-separation room were nonuniform, peaking in front of and between the huller-separator pairs. The high total mass readings show that workers were exposed to very high levels of nonthoracic airborne dust, which upon inhalation tends to deposit in the extrathoracic airways. The high elutriated mass concentrations suggest that workers were exposed to respirable cotton dust at levels higher than 1 mg/m3 mean concentration, the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) for cotton dust. Regressions between dust concentrations measured by stationary vertical elutriators and by personal samplers attached to workers serve for estimating the potential occupational exposure to cotton dust of workers in the hulling-separation room.

Air Pollutants, Occupational↗
PubMed2005

Characteristics of road dust from different sampling sites in northern Taiwan.

Road dust contributes a large percentage of the atmosphere's suspended particles in Taiwan. Three road dust samples were collected from downtown, electrical park, and freeway tunnel areas. A mechanical sieve separated the road dust in the initial stage. Particles > 100 microm were 75%, 70%, and 60% (wt/wt), respectively, of the samples. Those particles < 37 microm were resuspended in another mixing chamber and then collected by a Moudi particle sampler. The largest mass fraction of resuspended road dust was in the range of 1-10 microm. Ultrafine particles (< 1 microm) composed 33.7, 17, and 7.4% of the particle samples (downtown, electrical park, and freeway tunnel, respectively). The road dust compositions were analyzed by inductively coupled plasma (ICP)-atomic emissions spectroscopy and ICP-mass spectrometry. The highest concentration fraction contained more aluminum (Al), iron (Fe), calcium (Ca), and potassium than other elements in the road dust particle samples. Additionally, the sulfur (S) content in the road dust from the electrical park and freeway tunnel areas was 2.1 and 3.4 times the downtown area sample, respectively. The sulfur originated from the vehicle and boiler oil combustion and industrial manufacturing processes. Furthermore, zinc (Zn) concentration in the tunnel dust was 2.6 times that of the downtown and electrical park samples, which can be attributed to vehicle tire wear and tear. Resuspended road dusts (< 10 microm) from the downtown and freeway tunnel areas were principally 2.5-10 microm Al, barium (Ba), Ca, copper (Cu), Fe, magnesium (Mg), sodium (Na), antimony (Sb), and Zn, whereas arsenic (As), chromium (Cr), and nickel (Ni) were predominant in the ultrafine particle samples (< 1 microm). Al, Ba, and Ca are the typical soil elements in coarse particles; and As, and Cr and Ni are the typical fingerprint of oil combustion and vehicle engine abrasion in ultrafine particles. There was a special characteristic of resuspension road dust at electrical park, that is, many elements, including As, Ba, Ca, cadmium, Cr, Cu, Fe, manganese (Mn), Ni, lead (Pb), S, vanadium (V), and Zn, were major in ultrafine particles. These elements should be attributed to the special manufacturing processes of electric products.

Air Pollutants↗
PubMed1986

Laboratory evaluation of RDM-201 Respirable Dust Monitor.

The current paper discusses the results of laboratory experiments conducted to evaluate the GCA Respirable Dust Monitor RDM-201 in comparison with the standard Gravimetric Respirable Dust Sampler (GRDS). The samplers were compared in parallel within the atmosphere of an inhalation chamber laden with Arizona Fine Road Dust (AFRD). A wide range of dust concentrations (i.e., from 0.17 to 32:81 mg/m3) was used in the experiments. Sampling time varied from 15 to 120 min. There was a high agreement between the two GRDSs, particularly for samples with dust weight larger than 0.5 mg. The correlation and linearity between the RDM-201 display reading and the actual weight of dust on the instrument's filter were quite high for dust samples larger than 0.5 mg, but dropped significantly for samples less than 0.5 mg. Considering the extremely high dust concentration required to collect a minimum of 0.5 mg of respirable dust within 1-min sampling time of the RDM-201's automatic sampling mode, it was concluded that the use of automatic mode intended for quick evaluation of dusty atmosphere is impractical under most ordinary dusty conditions. The RDM-201 manual mode can be used, however, as reliably as a GRDS, for extended sampling times for assessment of TWAC of respirable dust in the atmosphere of a workplace, providing that a minimum of 0.5 mg sample is collected on the filter.

Air Pollutants, Occupational↗
PubMed1987

Capillary gas chromatography of cotton dusts associated with human pulmonary function studies.

The effects of geographical area of growth and cotton variety on pulmonary activity have been evaluated through human volunteer exposure studies conducted by NIOSH and USDA at the Cotton Quality Research Station, Clemson, S.C. These studies demonstrate that carding California cottons releases dust with less human pulmonary activity than dust released from the corresponding Mississippi cottons. Dust released from Texas cottons grown in 1982 was considerably less active than the dust from Texas cottons grown in 1983. Distinct differences in the chemical compositions of the Mississippi, Texas, and California cardroom dusts were found. Aqueous extracts of the dusts were freeze-dried and then derivatized. Capillary gas chromatography revealed that the California dust extracts and the 1982 Texas dust extract were characterized by relatively higher levels of malic acid, whereas the Mississippi dust extracts and the 1983 Texas dust extracts were characterized by relatively higher mannitol levels.

Byssinosis↗
PubMed1989

Reduction of airborne radioactive dust by means of a charged water spray.

An electrostatic precipitator based on charged water spray technology has been used in an underground uranium mine to control long-lived radioactive dust and short-lived aerosol concentration in a mine gallery where dust from a rock breaking/ore transportation operation was discharged. Two main sampling stations were established: one upstream of the dust precipitator and one downstream. In addition, dust samplers were placed at different locations between the dust discharge and the end of the mine gallery. Long-lived radioactive dust was measured using cascade impactors and nylon cyclone dust samplers, and measurement of the radioactivity on the samples was carried out by conventional methods. Radon and thoron progeny were estimated using standard techniques. Experiments were conducted under a variety of airflow conditions. A maximum radioactive dust reduction of about 40% (approximately 20% caused by gravitational settling) at a ventilation rate of 0.61 m3/sec was obtained as a result of the combined action of water scrubbing and electrostatic precipitation by the charged water spray electrostatic precipitator. This represents the optimum efficiency attained within the range of ventilation rates investigated. The dust reduction efficiency of the charged water spray decreased with increasing ventilation rate, i.e., decreasing air residence time, and hence, reduced dust cloud/charged water droplets mixing time.

Air Pollutants, Occupational↗
PubMedDate not supplied

Comparison of endotoxin assays using agricultural dusts.

Endotoxins from gram-negative bacteria pose a significant respiratory hazard. Establishing dose-response relationships is problematic because there are no standard procedures for sampling and analysis. The goal of this study was to compare endotoxin analyses in six laboratories using Limulus-based assays for analysis of organic dusts from three agricultural environments: chicken barns, swine barns, and corn processing facilities. For each dust generation experiment 14 side-by-side air samples were collected on 37-mm glass fiber filters at flows of 1.8 L/min. Each laboratory was randomly allocated two filters from each of seven experiments per dust type. Three laboratories used the QCL-1000 endpoint assay, and three used the kinetic-QCL method. To eliminate variability among different lots, a single lot of Limulus amebocyte lysate for endpoint assays and one similar lot for kinetic assays was provided. Precision of assays performed within labs was very good, with pooled coefficients of variation for replicate samples ranging from 1 to 11% over all labs and all dust types. There were significant differences between laboratories for all three dust types (p < 0.01). The pattern of differences between labs varied by dust type. For chicken dust, labs using the endpoint method reported higher results than those using kinetic methods. For swine and corn dusts, labs using the kinetic method reported the highest endotoxin values. For chicken dust, results from all labs except A and B were highly correlated (r = 0.86-1.00). For swine dust, only labs B and E, and C and D were correlated. For corn, A, B, and D were significantly correlated with most other labs. In conclusion, statistical differences in performance between laboratories were apparent and may be related to the extraction and analytical methods. The results of this study will be useful for standardization of sampling and analysis of airborne endotoxin in agriculture.

Agriculture↗
PubMed1998

Exposure to dust and its particle size distribution in California agriculture.

The aim of this study was to measure personal dust exposure levels and the dust particle size distribution during various agricultural operations in California. Personal dust exposure levels were measured with four-stage cascade impactors and respirable dust cyclones during field crop, fruit and nut farming, and dairy operations at three farms. Altogether, 103 cascade impactor measurements and 108 cyclone measurements were taken. High personal dust exposure levels were measured during various operations in particular during ground preparation operations such as land planing (geometric mean [GM] = 57.3 mg/m3, geometric standard deviation [GSD] = 2.4) and discing (GM = 98.6 mg/m3, GSD = 2.9). Dust particles were relatively large and the great majority belonged to the extrathoracic fraction. Dust levels were considerably lower when an enclosed cabin was present on the tractor; for example, during discing, dust exposure levels were reduced more than sixtyfold for the larger dust particle fraction and more than fourfold for the respirable dust fraction.

Agriculture↗
PubMed2004

Personal exposures to inorganic and organic dust in manual harvest of California citrus and table grapes.

The aim of this study was to determine characteristics of personal exposure to inorganic and organic dust during manual harvest operations of California citrus and table grapes. Personal exposures to inhalable dust and respirable dust were measured five times over a 4-month period of harvesting season. We analyzed components of the dust samples for mineralogy, respirable quartz, endotoxin, and total and culturable microorganisms. Workers manually harvesting were exposed to a complex mixture of inorganic and organic dust. Exposures for citrus harvest had geometric means of 39.7 mg/m(3) for inhalable dust and 1.14 mg/m(3) for respirable dust. These exposures were significantly higher than those for table grape operations and exceeded the threshold limit value for inhalable dust and respirable quartz. Exposures for table grape operations were lower than the threshold limit value, except inhalable dust exposure during leaf pulling. Considered independently, exposures to inhalable dust and respirable quartz in citrus harvest may be high enough to cause respiratory health effects. The degree of vigorous contact with foliage appeared to be a significant determining factor of exposures in manual harvesting.

Adult↗
PubMed1994

Measurements of the effectiveness of dust extraction systems of hand sanders used on wood.

An investigation has been made of the production of dust by hand sanders when used without dust extraction, with integral dust extraction and with external dust extraction. The apparatus used for the measurement was designed to carry out sanding in a repeatable manner, simulating normal working practice. The geometry of the wood sanded affects the dust concentration critically, whereas the effects of the sandpaper grade and of the filtration efficiency of the collection system are small. Belt sanders produce high dust levels in all situations, but they are very efficient in removing wood, which means that they need to be used for only a short period. The integral systems of orbital sanders give good dust control on flat wood but not on edges. The high air extraction rate of external systems results in much better dust control during the sanding of edges, though the performance of the two extraction systems on flat wood is broadly similar. The size distribution of the dust clouds produced by the sanding is relatively constant, but that produced by rotary sanders tends to be coarser than that produced by orbital sanders, consistent with the smoother finish given by the latter. The electric charge on the dust produced by sanding is high.

Air Pollutants, Occupational↗