Total Dust Levels Research Articles

Effects of repeated swine building exposures on normal naive subjects.

Exposure to swine confinement buildings has a negative impact on respiratory health. A short exposure to this environment results in an acute airway inflammatory response. The present study was performed to confirm and further define the acute effects of working in a swine building, and to determine whether these effects are reproducible. Seven previously nonexposed normal subjects underwent evaluations that included hourly measurement of forced expiratory volume in one second (FEV1), methacholine challenge (the provocative concentration producing a 20% fall in FEV1 (PC20)), bronchoalveolar lavage (BAL), nasal lavage (NL), and blood analyses, before (control) and after each of two 5 h exposures to a swine building environment. The exposures were conducted 8 days apart. The levels of total dust, endotoxins, and ammonia (NH3) in the confinement building were measured on each day of exposure. Both exposures resulted in a significant reduction in FEV1 (mean+/-SEM change in FEV1: control = 7+/-2%; exposure 1 = 15+/-3%; exposure 2 = 23+/-3%), decrease in PC20 (median value (25th-75th percentile): 223 (23-256), 20 (15-198) and 20 (11-71), respectively; p=0.05) and increase in BAL cells (129+/-20, 451+/-43 and 511+/-103x10(3) cells x mL(-1), respectively) and NL cells (6+/-4, 126+/-58 and 103+/-26x10(3) cells x mL(-1), respectively), mostly neutrophils. Levels of interleukin-8 (IL-8), but not interleukin-1 (IL-1) or tumour necrosis factors (TNF-alpha), increased both in BAL and nasal fluids with exposure. In normal naive subjects, repeated exposure to the environment of a swine building induced a marked and reproducible reduction in forced expiratory volume in one second, increase in airway responsiveness, and increased neutrophilic inflammatory response. These results could not be accounted for by any of the environmental factors measured.

Air Quality in a Multiple Tier Rearing System for Layer Type Pullets

New rearing systems for laying hens must be developed as the result of animal welfare legislation in Sweden that will ban the use of cages. The up-breeding of layer-type pullets must also take place in systems similar to those used in egg production units. In this study, the air quality and the climatic conditions in a multiple tier rearing system were compared with conditions in a battery system. The studies were run simultaneously with layer-type pullets from one day old to 16 weeks of age. The gases measured were ammonia and carbon dioxide and the particulate matter was measured as total dust, respirable dust, endotoxin, and airborne microorganisms. The results indicate significantly higher levels of total dust and endotoxin in the multiple tier rearing system than in the battery system. This was most obvious at the end of the rearing period. Airborne microorganisms were found in considerable concentrations in both systems. When animals were unloaded, personal sampling gave elevated levels of dust that exceeded the Swedish hygienic threshold value. This may be related to a raised activity of the animals and to the close contact between the workers and the animals.

Lung Function in Woodworking Teachers in Sweden.

Work-related airways symptoms are common in woodworkers. To study possible work-related effects on lung function, 40 exposed woodworking teachers and 31 controls were examined by spirometry, diffusion-capacity and nitrogen-washout determinations, and methacholine challenge. Measured levels of total and respirable dust and terpene concentrations in the shops were below the Swedish threshold-limit values. Lung-function values on Monday morning were similar in the two groups. Slight obstructive impairments during the working week were found in both groups. In the woodworking teachers, small changes in lung function were related to measured total dust, use of process ventilation, and use of a broom to clean the benches. Their methacholine reactivity was slightly more pronounced compared with that of the controls, but the numbers of hyperreactive individuals (PC&inf20; < 8 mg/m(3)) were equal in the two groups. These facts might indicate small work-related effects on lung function, but some contradictory findings disturb this interpretation. The results are therefore inconclusive.

Improved nasal clearance among pulp-mill workers after the reduction of lime dust.

The purpose of this study was to investigate nasal symptoms and function among workers exposed to lime dust and to determine if a reconstruction of the workplace improved the worker's nasal health. In 1992, pulp-mill workers (N = 15) exposed to lime dust and an equal number of matched unexposed referents were examined by questionnaires, nasal peak expiratory flow, the saccharin test, nasal lavage, and a clinical examination of the upper airways. The study was repeated one year later, after the pulp mill had been rebuilt. Dust levels were measured on both occasions with stationary and personal samplings. In 1992 the total dust level was 1.2 mg.m-3. The saccharin test showed a significantly increased nasal transit time for the exposed workers in comparison with that of the unexposed referents (difference 3.5 min, 95% confidence interval 0.1-6.9 min). One year later the dust levels had decreased to 0.1 mg. m-3, and the difference in nasal transit time had decreased (difference- 0.8 min, 95% confidence interval -4.8-3.3 min). Workers exposed to lime dust have an impaired mucociliary function. This impairment is probably due to the alkalinity of the lime. When dust levels are reduced, mucociliary function improves; therefore renovating a workplace to reduce dust levels has a positive effect.

Exposure to airborne microbes during the repair of moldy buildings.

Concentrations of airborne microbes, studied during the repair of seven moldy buildings, showed that concentrations of airborne fungi increased during the repair work. This was especially true during the demolition of moldy building materials, even though the total dust levels remained low. Concentrations of viable fungi sampled with a six-stage cascade impactor were 10(3) - > 1.9 x 10(5) cfu/m3, and the total concentrations of fungal propagules, as determined by the Camnea method (i.e., air filtration method with epifluorescence microscopic counting of acridine-stained organisms) showed 10(5)-10(6) counts/m3 during the demolition. Penicillium was the main genus throughout. Concentrations of viable total bacteria also increased, but this change proved less noticeable than that of the fungi. However, rather high concentrations of viable actinomycetes up to 10(4) cfu/m3 were detected during the demolition. Results show that construction workers are exposed to high concentrations of microbes, perhaps causing health problems. Thus, personal protection of both the respiratory system and eyes is strongly recommended for workers as they repair moldy buildings. In addition, the repair room should be isolated from other areas to protect occupants or any other people present.

Detection of airborne natural rubber latex by immunoelectrophoresis, RAST inhibition, and immunospot method.

Occupational dermal and respiratory allergies caused by natural rubber latex (NRL) have been encountered with increasing frequency in health care workers. In order to measure the amount of airborne NRL, area and personal air sampling was performed in three hospital laboratories where workers used latex gloves. The total dust levels in laboratory air samples were lower than 0.17 mg/m3. RAST inhibition suggested that NRL antigens may exist both in the area and personal samples. Immunospot measurements, rocket immunoelectroporesis, and rocket radioimmunoelectrophoresis did not show any NRL activities in laboratory airsamples, although they were able to detect immunoactive material in positive control filter specimens. We conclude that the airborne NRL concentration was undetectable in daily hospital laboratory environment where workers used disposable NRL gloves. Airborne NRL, however, can be measured by using immunological assays.

Level and distribution of employee exposures to total and respirable wood dust in two Canadian sawmills.

Personal respirable (N = 230) and total (N = 237) dust measurements were made in two coastal British Columbia sawmills using a sampling strategy that randomly selected workers from all jobs in the mills over two seasons. Information about job title, department, season, weather conditions, location of the job relative to wood-cutting machines, and control measures also was collected at the time of sampling. Only 16 respirable wood dust samples were above the detection limit of 0.08 mg/m3; all 16 had levels < or = 0.20 mg/m3. Total wood dust concentrations were also low (36% less than the detection limit), with a mean of 0.51 mg/m3, and ranging from < 0.08 to 52 mg/m3. Measurements of exposure taken close to chippers, planers, and multiple saws had the highest total wood dust levels. Sawmill department and booth enclosures also were associated with wood dust concentrations, while local exhaust ventilation and weather conditions were not. Wood dust levels in this study were generally lower than in other studies of this industry, but most sawmill investigations report mean wood dust concentrations lower than those measured in the furniture and cabinetmaking industries, where concerns about wood dust exposures initially were raised.

Respiratory symptoms and bronchial reactivity among pig and dairy farmers.

This study assessed the prevalence of respiratory manifestations among French pig and dairy farmers and determined the relationship between bronchial reactivity and respiratory manifestations. The pig farmers included 102 men working more than half-time inside swine confinement buildings. There were 51 male dairy farmers and 81 male referents. The demographic characteristics of the three groups were similar except for more smokers among the referents. Each subject completed a standardized questionnaire. Pulmonary function tests were performed before and after a methacholine challenge (cumulative doses 80, 240, and 560 micrograms). Airborne dust, ammonia, and carbon dioxide were measured inside 28 swine confinement buildings. The pig farmers were exposed to a total dust level of 2.41 mg.m-3. The respirable particle concentration was low. The pig and dairy farmers had a significantly higher prevalence of cough and morning phlegm than the referents. Before the methacholine challenge, the dairy farmers had nonsignificantly lower mean lung function values than the other groups. Among the subjects with no history of asthma, nonspecific bronchial hyperreactivity was significantly higher among the pig and dairy farmers than among the referents. There was a fall in the forced expiratory volume in 1 s (FEV 1.0) that was greater than 10% in 6.7% of the referents, 17.9% of the swine workers, and 35.6% of the dairy farmers. This result was unchanged after adjustment for the initial FEV1.0. The prevalence of respiratory symptoms was significantly higher among the pig farmers without base-line lung function impairment. However, both the pig and the dairy farmers had increased bronchial reactivity.

Health effects of exposure to endotoxins and organic dust in poultry slaughter-house workers

Twenty-three dust-exposed shacklers in the hanging departments of four poultry slaughter-house plants were examined immediately before work on a Monday morning with a standardized interview, pulmonary function tests (VC and FEV1), and blood sampling for analysis of complement factors. The examinations were repeated immediately after work the same day. Further, the individual breathing zone levels of both total dust and endotoxins were monitored during the whole work-shift. Moreover, spot samples of airborne bacteria and fungi were collected. The mean level of total dust was 6.3 mg/m3 (range 0.4-15.3 mg/m3) and of endotoxins 0.40 micrograms/m3 (range 0.02-1.50 micrograms/m3). Total levels of 4 x 10(5)-4 x 10(6) cfu/m3 of airborne bacteria, mainly coagulase-negative staphylococcal strains, but only 500-4000 cfu/m3 of fungi were found in the hanging departments. An over-shift increase in respiratory symptoms was found, but none of the workers had experienced any symptoms indicating extrinsic allergic alveolitis (EAA) or organic dust toxic syndrome (ODTS). Further, mean over-shift decreases of VC (3.1%) and FEV1 (4.1%) were found, indicating a harmful effect on the bronchi. There were, however, no associations between these over-shift decreases and the individual time-weighted average breathing zone levels of either total dust or of endotoxins. No over-shift change in serum complement factors was observed.

Dust Control in Peanut Grading Rooms

Federal and State Inspection Service concerns for the health and safety of inspectors in peanut grading rooms prompted research to reduce respirable, inhalable and total dust levels. A laser particle counter and a high volume air sampler were used to determine particle sizes and concentrations. A filtering system was designed to reduce dust concentrations to tolerable levels, with an emphasis on removing the particle size range that contains Aspergillus flavus mold spores. The system utilizes filters with an efficiency of 90% to 95% and arrestance of 99% while filtering all of the air in the grading rooms every two minutes..

Mortality and cancer incidence among workers in an abrasive manufacturing industry.

Earlier epidemiological studies have shown that exposure to aluminium oxide and silicon carbide might carry with it an increased risk of lymphomas, stomach cancer, and non-malignant respiratory disease. To elucidate further this possible hazard, the cancer morbidity and the total mortality pattern was studied among 521 men manufacturing abrasive materials who had been exposed to aluminium oxide, silicon carbide, and formaldehyde. Total dust levels were in the range of 0.1-1.0 mg/m3. The cohort was followed up from 1958 until December 1983. No significant increase was found in total mortality, cancer mortality, or incidence of non-malignant respiratory diseases.

Respiratory effects and dust exposures in hog confinement farming.

Fifty-three hog confinement farmers and 43 control farmers were studied. Pulmonary function, total and respirable personal dust levels, and responses to a health status questionnaire were obtained for all farmers. The hog farmers' total and respirable personal dust exposures were significantly higher than the respective levels of the control farmers. Higher dust levels were associated with the use of floor (scatter) feeding, indoor feed grinding, and the use of high moisture corn feed. Pork producers reported respiratory symptoms significantly more often than controls. Lung function did not differ between the two groups of farmers, nor could dust exposure levels be related to lung function.

Rapid decline in FEV1 in grain handlers. Relation to level of dust exposure.

We have prospectively studied the respiratory health of a cohort of grain elevator workers in the Canadian west coast terminal elevators, beginning in 1975 and following them for 6 yr. We have used a "nested" case-control model to identify determinants of the worst trend in FEV1 over this period. The 10% of participants in this category had a mean decline of greater than 100 ml/yr. They were significantly more likely to have had a decline in FEV1 over a work week and to have nonspecific bronchial hyperreactivity. There was a significant relationship between the odds ratio of being a case and the mean level of dust exposure associated with the job and location at the work site; cases were associated with mean total dust levels greater than 5 mg/m3. We found no relationship between the odds ratio of being a case and a number of host factors, such as immediate skin reactivity to common allergens, history of asthma, bronchitis, or hay fever, or presence of respiratory symptoms. We conclude that exposure to grain dust at levels greater than 5 mg/m3 is associated with a serious adverse trend in FEV1.

Lung function measurements over 21 days shiftwork in steelworkers from a strandcasting department.

On the assumption that short term changes in lung function may reflect the potential for a long term decline the evolution of lung function indices in 25 steelworkers from a strandcasting department and in 11 comparable steelworkers not exposed to dust was investigated over an almost uninterrupted 21 day working period and over three different workshifts. The mean total dust level in the strandcasting department, assessed by personal sampling, was 11.8 mg/m3. All subjects were examined at the beginning, in the middle, and at the end of their first (day 1) morning shift (0600 to 1400), their last (day 14) afternoon shift (1400 to 2200), and their last (day 21) night shift (2200 to 0600). Indices measured were vital capacity (VC), forced expiratory volume in one second (FEV1) and in three seconds (FEV3), forced expiratory flow over the middle half of the forced vital capacity (FEF25-75), peak expiratory flow rate (PEFR), the slope of the N2 plateau (delta N2) and the closing volume (CV) of the single breath oxygen test. Differences in indices between initial values (0600 on day 1) and final values (0500 on day 21) were not significant in the control group (except delta N2 which became lower); in the casting group there were significant (p less than 0.05) decreases in FEF25-75 and FEV3, but these decreases were not significantly greater than in the control group. Lung function changes were not significant in either group over the morning shift. During the afternoon there were significant decreases in spirometric indices in the casting group, with no significant decreases in the control group, but the interactions between exposure and time were generally not significant. During the night shift, however, the decreases in FEV1 and FEF25-75 observed in the strandcasting group were significantly more pronounced than in the control group. The single breath test, which many subjects failed to perform correctly on each occasion, showed no significant changes in closing volumes, and an "improvement" of delta N2 over the morning and the night shift in the control but not the exposed subjects needs to be interpreted with caution. The more pronounced decrease in spirometric indices, suggestive of slight airways obstruction, found over the night shift in the strandcasting workers is attributed to their working environment.

Properties and toxicity of airborne wood dust in woodworking establishments

The total suspended dust levels, particle shape and size distributions and metal concentrations (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) of wood dust in the breathing zone of 3 small woodworking establishments were monitored. In vitro culture assay indicated that the mortality of alveolar macrophage was related to the metal content of dust collected from these 3 workplaces.

Environmental Study of Poultry Confinement Buildings

Environmental measurements were made in three poultry confinement buildings in order to characterize gas and particulate contaminants. Levels of total and respirable dust averaged 4.4 and 0.24 mg/m3, respectively. Particle size distribution as measured by cascade impactors was similar in the three confinement houses with a mass median aerodynamic diameter of about 15 microns and a geometric standard deviation of about 2.2. Ammonia levels measured in the active areas of the buildings averaged about 25 ppm. Ammonia concentration was quite high, however, in an unused and unventilated portion of one of the buildings (mean = 170 ppm). CO2 levels ranged from 0.05-0.1%. Levels of CO, H2S, NO2, NOx, CH4, mercaptan, formaldehyde, and hydrocarbons were all below the limit of detection for indicator tubes. Concentrations of airborne bacteria and fungi were on average about 1.5 X 10(5) and 1.0 X 10(4) colony-forming units/m3, respectively. Endotoxin analysis was also performed on the total and respirable dust samples. Endotoxin levels (expressed in air concentration) ranged from 0.77 to 61 ng/m3 for total dust and from 0.71 to 15 ng/m3 for respirable dust. Endotoxin was also measured on the collection media from the individual impactor stages. Endotoxin was detected in all size ranges with the highest concentration of endotoxin per unit of dust found in the smallest (less than approximately 3.5 microns) size fraction. The endotoxin levels tend to be lower than those previously reported in poultry operations.

Acute effects of grain dust exposure during a work shift.

We studied 248 grain handlers and 192 city services workers (control subjects) before and after an 8-h work shift and measured total dust levels using personal samplers. We found that grain workers exposed to a mean total dust level of 3.3 +/- 7.0 mg/m3, when compared with control subjects, had (1) a higher prevalence of work-related respiratory symptoms (p less than 0.05) and significant decrements in forced-expiratory volume in one second (FEV1) and maximal flow rates after exhalation 50 and 75% of forced vital capacity (Vmax50 and Vmax75) during the work shift, and (2) significant differences (p less than 0.05) in preshift/postshift percent changes in forced vital capacity (FVC), Vmax50 and Vmax75. Adjusting for age, height, and smoking habit, grain handling still had a significant negative effect on FVC, Vmax50, and Vmax75. In grain workers, we found a significant (p less than 0.05) negative relationship between total dust levels and the percent change in FVC, Vmax50, and Vmax75 and a positive relationship between dust level and percent change in leukocyte counts. Grain workers' perception of dust level correlated with the measured dust level and the prevalence of symptoms. Occupational exposure to grain dust during a work shift has a dose-related adverse acute respiratory effect regardless of smoking habit, atopic status, or age, and it produces a dose-related leukocyte response at total dust levels below 15 mg/m3.

Effect of Dust-Control Additives on the Open-End Spinning Performance of Cotton

The effect of small amounts of dust-suppressant additives in processing cotton into open-end spun yarns was examined. Additives applied batchwise or continuously in the blowroom substantially reduced total and respirable dust levels in carding; how ever, all additives also reduced OE yarn strength and extensibility and markedly increased rotor deposit rates.

An Epidemiologic Study of the Respiratory Effects of Trona Dust

Trona (sodium sesquicarbonate) is mined from an underground deposit in Wyoming and processed for use in glass, paper, detergent, and chemical applications. Trona dust is alkaline (pH 10.5) and can have an irritant effect on respiratory airways, mucous membranes, and the skin. A study population of 142 underground miners and 88 surface workers from one facility volunteered for an epidemiologic study. Their mean age was 37.6 yr and mean duration of employment was 10.0 yr. The percentage with chronic cough and phlegm was 23%; both symptoms were more common among smokers than nonsmokers. Thirty-three percent of the workers complained of dyspnea when hurrying on level ground or walking up a slight hill. Half of the workers complained of upper respiratory tract symptoms and eye irritation. Both smokers and exsmokers had significant declines of forced expiratory volume in 1 sec (FEV1.0) with age; exsmokers also had declines with work-years when compared to a nonsmoking comparison population. Nonsmokers with personal dust measurements had a significant decline of FEV1.0 related to respirable dust exposure. A shift study of 104 workers revealed a significant fall in FEV1.0 among nonsmokers and surface workers. Significance was approached in the high dust exposure group. An increase in the mean percent predicted forced vital capacity and FEV1.0 was shown for the 125 workers who had a 5-yr follow-up of pulmonary function. There was no correlation between the shift study decrements and the longitudinal 5-yr follow-up. Industrial hygiene dust sampling found elevated levels of total dust but lower respirable dust, with no detectable free silica.

Effect of Mount St. Helens’ Volcanic Ash on Broiler Performance and Health and on House Environment ,

An experiment involving approximately 1300 broilers was carried out in an uninsulated, windowless, negative pressure, mechanically ventilated house to study the effects of Mount St. Helens’ volcanic ash (VA) on broiler performance, health, and house environment. Four treatments were no VA exposure or control; one direct application of VA (10 kg/m2) on wood shaving litter at 20 days of age, and either VA blown in the pens for 1 hr (VA1; calculated at 38.2 g/min for 2 hr) or 3 hr (VA3; calculated at 22.6 g/min for 6 hr) in the morning and afternoon, daily, from day 20 of production. Volcanic ash from the June 12, 1980 eruption was used. The birds were exposed to VA for 28 days.No significant differences among the treatments were observed on mean body weights by sexes, feed conversion, ammonia levels in the pens, percent mortality, and carcass quality. As would be expected, total dust levels were higher from 0830 to 1630 hr (8.5 hr) when VA was blown into the pens than during the period with no VA blown into the pens (1630 to 0830 hr; 15.5 hr). There was some recycling of dust during the period with no ash infusion. Respiratory dust levels (particles ranging in size from .5 to 10 μm diameter) were significantly higher in direct application and VA3 treated pens than either the control or VA1 treated pens. Mean litter moisture levels were significantly lower in VA3 than in VA1 treated pens, but both ash treatments had significantly lower litter moisture levels than in the control pens. In the lung tissues, varying degrees of lymphoid hyperplasia, smooth muscle hyperplasia, and macrophage infiltration were found. In birds exposed for 28 days either to VA1 or VA3 treatments, crystalline structures were found in alveolar macrophages. Moderate lymphoid hyperplasia was found in the lung tissue from birds exposed to either direct application of VA on the litter or no exposure to VA. Microscopic examination of the turbinates for all treatments revealed no significant changes. There was a random distribution of mild tracheitis in all birds examined from all treatments. Broiler performance, carcass quality, and health were not affected, even though lung tissues were damaged by prolonged exposure of broilers to the dusty environment created in this study.