Mean Dust Concentration Research Articles

Characterization of an aerosol chamber for human exposures to endotoxin.

The objective of this study was to develop and characterize an exposure chamber in which human subjects could be exposed to low dust concentrations carrying an endotoxin coating. An exposure chamber, dust dispersion method, and endotoxin characterization technique were developed for inhalation exposures. A 6.27 m3 exposure chamber was designed and constructed from cinder block, glass windows, and Plexiglas. Using an acetone adhesion process, Enterobacter agglomerans were adsorbed onto respirable cellulose particles to create the endotoxin aerosol. The size distribution of the endotoxin-treated particles was verified using light microscopy and cascade impactors. A dry powder dust generator was refined to consistently disperse small quantities of the aerosol into the chamber to maintain dust concentrations at approximately 250 micrograms/m3. Dust levels during the chamber exposures were monitored using a portable continuous aerosol monitor (PCAM). During initial exposure runs, PCAM monitoring stations were positioned at different locations within a 0.5-meter matrix to document mixing patterns. Total dust and cascade impactor samples were collected throughout each exposure period to characterize the chamber operating system and insure the mean airborne dust concentration fulfilled target levels. A one-factor analysis of variance at the 95 percent confidence interval illustrated that there was not a statistically significant difference in the mean dust concentration throughout the exposure runs compared to the individual runs. Together the consistency of the total dust filters, endotoxin concentrations, and aerosol-monitoring instrument were adequate to allow use of the chamber for experimental studies involving human volunteers.

Ventilatory function and personal breathing zone dust concentrations in Lancashire textile weavers.

BACKGROUND: To report findings on ventilatory function and estimations of concentrations of personal breathing zone dust in Lancashire textile weavers. Weaving room dust is considered to be less harmful than...

Concentrations and Emissions of Airborne Dust in Livestock Buildings in Northern Europe

Field surveys of dust concentrations within and dust emissions from cattle, pig and poultry buildings were conducted in England, the Netherlands, Denmark and Germany. Measurements of inhalable and respirable dust concentrations were made in 329 buildings. Concentrations of CO 2 within and outside the buildings were also measured to estimate ventilation rates for dust emission calculations. Dust concentrations and emissions were a⁄ected significantly by housing type and animal species. Overall mean inhalable and respirable dust concentrations were 0)38 and 0)07 mg/m3 in cattle buildings, 2)19 and 0)23 mg/m3 in pig buildings, and 3)60 and 0)45 mg/m3 in poultry buildings, respectively. Overall mean inhalable and respirable dust emission rates from the buildings were 110 and 19 mg/h bovine, 111 and 14 mg/h pig, and 12 and 2 mg/h bird, respectively. Expressed per 500 kg liveweight, the values become, respectively, 145 and 24 mg/h for cattle; 762 and 85 for pigs; and 3165 and 504 for poultry. Seasonal e⁄ects on dust concentrations in and emissions from cattle buildings were weak. Dust concentrations in pig and poultry buildings were higher in winter than summer. Inhalable dust emission rates from pig and poultry buildings were higher in summer than winter. E⁄ects of season on respirable dust emission rates from pig and poultry buildings were small. Inhalable dust concentrations in cattle buildings were higher in the day than at night, but e⁄ects di⁄ered between countries. Pig buildings showed higher dust (both inhalable and respirable) concentrations in the day than at night. Percheries and buildings for caged layers showed higher inhalable dust concentrations in the day than at night. However, dust concentrations in broiler houses were not a⁄ected by day and night. The high concentrations of inhalable dust in broiler houses, in percheries for hens and in slatted weaner and fattener houses for pigs give cause for concern for both stockman and animal health and performance. ( 1998 Silsoe Research Institute

Respiratory health effects of opencast coalmining: a cross sectional study of current workers.

OBJECTIVE: To identify whether there is evidence of pneumoconiosis and other respiratory health effects associated with exposure to respirable mixed dust and quartz in United Kingdom opencast coalmines. METHODS: A...

Comparison of IEUBK model predictions and actual blood lead values at a former battery recycling site

This paper presents an evaluation of US EPA's integrated exposureuptake biokinetic model for lead (IEUBK model) using data obtained during emergency removal operations at a former lead-acid battery recycling plant and the surrounding community. Data employed in the study include soil lead and interior dust lead, air lead levels collected at the site perimeter, drinking water lead levels at the community water main and blood lead data collected from an annual blood lead monitoring programme conducted over a four year period during the remediation activities.Geometric mean soil and dust concentrations were found to be a better predictor of blood lead than arithmetic mean data. However, weight based dust lead data were believed to be an inappropriate measure of dust lead levels. Estimates of household dust lead concentrations based upon surface loading data (μg m(-2)) yielded blood lead predictions which were more consistent with data collected in the blood lead monitoring programme.

Meteorological factors causing high dust concentration

Mean dust concentration measured by a high-volume air sampler in Osaka City was related with several meteorological factors (precipitation, wind velocity, wind direction and temperature difference between Osaka and Mt. Ikoma). Moreover, the contribution from the main dust sources was estimated by using metal and ion concentrations during high concentration periods and elemental source profiles.

Microanalyses of lesions and lymph nodes from coalminers' lungs.

The dust content and composition of lesions and hilar lymph nodes from the lungs of British coalworkers have been examined. Samples of macules, fibrotic nodules, and massive fibrosis (both peripheral and central sites) were dissected from 49 lungs. The highest mean dust concentrations (about 20%) were found in nodules and massive fibrosis. Overall there were no significant differences between the selected lesion types and their respective whole lung dust composition, although the central sites of massive fibrosis were found to contain on average a higher proportion of coal and a lower proportion of ash and its measured constituents, quartz and kaolin plus mica, than the edge of the lesion (p less than 0.001 for each component). There were striking differences between recovered lung and lymph node dusts. An examination of 180 specimens showed a mean quartz in lymph node dust of 20.3% compared with 6.1% in lung dust. As expected the proportion of quartz was greater in lymph nodes and lungs from men who had worked "low" rank (high ash) coal. By contrast with the corresponding figures for lung dusts, however, the mean proportion of quartz in nodes did not increase over the pathological range of pneumoconiotic lung disease. On average the proportions of kaolin and mica in lymph nodes reflect those found in lungs. The lymphotrophic nature of quartz was clearly shown although it was not possible to show an association between this clearance pathway and any particular type of lesion.

Respiratory response in simultaneous exposure to flax and hemp dust.

Abstract Žuskin, E., and Valic, F. (1973).British Journal of Industrial Medicine,30, 375-380. Respiratory response in simultaneous exposure to flax and hemp dust. The effect of exposure to high concentrations of mixtures of hemp and flax dust was studied in 124 workers in two textile mills (mill A: 65-70% hemp and the rest flax, mean dust concentration 13·9 mg/m3; and mill B: about 35% hemp and the rest flax, mean dust concentration 15·8 mg/m3). A high prevalence of byssinosis was found in both mills (80% in mill B; 46·8% in mill A) after a mean exposure of no more than 13 years. In both mills, byssinotics had a higher prevalence of all chronic respiratory symptoms than non-byssinotics. This difference was more pronounced in mill A. Forty-eight percent of byssinotic women and 43% of byssinotic men had byssinosis of grade 2 or 3. Significant mean acute reductions in FEV1·0 and ˙Vmax 50% VC on Monday were recorded in subjects with and without byssinosis with a significantly larger mean reduction in byssinotics (FEV1·0, P < 0·01; ˙Vmax 50% VC, P < 0·05). ˙Vmax 50% VC proved to be a more sensitive test for detecting acute effects of vegetable dust than FEV1·0. The acute respiratory response of the subjects exposed to similar concentrations of flax and mixtures of two different proportions of flax and hemp dust was found to be equal.

A clinical and environmental study of byssinosis in the Lancashire cotton industry.

The prevalence of byssinosis was measured in a population of 189 male and 780 female workers employed in three coarse and two fine cotton mills. Ninety-eight per cent. of the male and 96% of the female population were seen. The workers were graded by their histories as follows: Grade 0—No symptoms of chest tightness or breathlessness on Mondays Grade ½—Occasional chest tightness on Mondays, or mild symptoms such as irritation of the respiratory tract on Mondays Grade 1—Chest tightness and/or breathlessness on Mondays only Grade 2—Chest tightness and/or breathlessness on Mondays and other days The dust concentrations to which the workers were exposed were measured with a dust-sampling instrument based on the hexhlet. Altogether 505 working places were sampled. In the card-rooms of the coarse mills 63% of the men and 48% of the women had symptoms of byssinosis. In the card-rooms of the fine mills the corresponding prevalences were 7% for the men, and 6% for the women. Prevalences were low in the spinning-rooms in the coarse mills. The mean dust concentrations in the different rooms ranged from 90 mg./100 m.³ in one section of the card-room in a fine mill, to 440 mg./100 m.³ in one of the card-rooms of the coarse spinning mills. The prevalence of byssinosis in the different rooms was closely related to the overall dustiness (r = 0·93). For the three main constituents of the dust, namely, cellulose, protein, and ash, the prevalence of byssinosis correlated most highly with protein, particularly with the protein in the medium-sized dust particles, <i>i.e.,</i> approximately 7 microns to 2 mm. The symptoms of byssinosis may be caused by something in the plant débris which affects the respiratory tract above the level of the terminal bronchioles. This is the site where the medium-sized dust deposits. The possible importance of the fine dust is discussed. For routine measurements in industry, it is necessary to have a method of assessing dustiness in which the sampling equipment is simple and assessment rapid. As total dust concentration is relatively easy to measure, and correlates closely with the prevalence of byssinosis, permissible levels of dustiness have been expressed in terms of total dust. On comparing the prevalence of byssinosis among workers with short and long exposures and low and high concentrations (Table 11), it appears that a mill with a concentration of 100 mg./100 m.³ or less would be reasonably safe, but in dusty card-rooms it seems that such levels are not possible to achieve at present. As it is necessary to adopt a realistic target that can be achieved, it is suggested that dust concentrations in cotton mills should be less than 250 mg./100 m.³ and that periodic medical examinations should be adopted to protect susceptible workers who can be advised to leave their dusty environment before they are permanently disabled.