Mass Of Respirable Dust Research Articles

About the informativeness of hygienic control of the mass of respirable dust in the enterprise workers

The exhibition features industrial aerosols must be installed with the features of inhaling harmful substances and the physicochemical properties that affect the behavior of solid particles of the aerosol in the respiratory tract of a person, which will contribute to reducing the uncertainty in assessing the level of occupational risk to workers of dust professions.

A thermogravimetric analysis application to determine coal, carbonate, and non-carbonate minerals mass fractions in respirable mine dust

Occupational lung diseases such as coal worker’s pneumoconiosis, often called black lung, are caused by exposures to respirable coal mine dust. Dust composition is increasingly understood as an important disease factor, and it can vary significantly depending on dust source materials and generation processes. For regulatory compliance purposes, the mass concentration and quartz percentage of respirable dust are monitored in U.S. coal mines, but the whole composition is not typically determined. Previous work has indicated that thermogravimetric analysis (TGA) can be used to apportion the respirable dust mass to three important component fractions (i.e., coal, non-carbonate minerals, and carbonate), which should generally correlate with three different dust sources (i.e., coal strata, rock strata, and limestone rock dusting products being applied in the mine). However, a primary shortcoming of that previous work was use of fibrous sampling filters, which limited dust recovery and thus analytical accuracy. Here, an improved TGA application is presented using smooth polycarbonate filters. Based on experiments with laboratory-generated dust samples (masses ranging between 95–1,319 µg), the TGA-derived mass fractions (reported as percentage values) for all three components were found to generally be within ±10% of expected values.

Respirable size-selective sampler for end-of-shift quartz measurement: Development and performance

ABSTRACTAims of this study were to develop a respirable size-selective sampler for direct-on-filter (DoF) quartz measurement at the end-of-shift (EoS) using a portable Fourier transform infrared (FTIR) spectrometer and to determine its size-selective sampling performance. A new miniaturized sampler has been designed to have an effective particle deposition diameter close to the portable FTIR beam diameter (6 mm). The new sampler (named the EoS cyclone) was constructed using a 3D printer. The sampling efficiency of the EoS cyclone was determined using polydisperse glass sphere particles and a time-of-flight direct reading instrument. Respirable dust mass concentration and quartz absorbance levels of samples collected with the EoS cyclone were compared to those collected with the 10-mm nylon cyclone. The EoS cyclone operated at a flow rate of 1.2 l min−1 showed minimum bias compared to the international standard respirable convention. The use of the EoS cyclone induced respirable dust mass concentration results similar but significantly larger (5%) than those obtained from samples collected with 10-mm nylon cyclones. The sensitivity of the DoF-FTIR analysis in estimating quartz was found increased more than 10 times when the samples were collected with the EoS cyclone. The average particle deposition diameter was 8.8 mm in 60 samples. The newly developed user friendly EoS cyclone may provide a better sampling strategy in quartz exposure assessment with faster feedback.

The Generation Rate of Respirable Dust from Cutting Fiber Cement Siding Using Different Tools.

This article describes the evaluation of the generation rate of respirable dust (GAPS, defined as the mass of respirable dust generated per unit linear length cut) from cutting fiber cement siding using different tools in a laboratory testing system. We used an aerodynamic particle sizer spectrometer (APS) to continuously monitor the real-time size distributions of the dust throughout cutting tests when using a variety of tools, and calculated the generation rate of respirable dust for each testing condition using the size distribution data. The test result verifies that power shears provided an almost dust-free operation with a GAPS of 0.006 g m-1 at the testing condition. For the same power saws, the cuts using saw blades with more teeth generated more respirable dusts. Using the same blade for all four miter saws tested in this study, a positive linear correlation was found between the saws' blade rotating speed and its dust generation rate. In addition, a circular saw running at the highest blade rotating speed of 9068 rpm generated the greatest amount of dust. All the miter saws generated less dust in the 'chopping mode' than in the 'chopping and sliding' mode. For the tested saws, GAPS consistently decreased with the increases of the saw cutting feed rate and the number of board in the stack. All the test results point out that fewer cutting interactions between the saw blade's teeth and the siding board for a unit linear length of cut tend to result in a lower generation rate of respirable dust. These results may help guide optimal operation in practice and future tool development aimed at minimizing dust generation while producing a satisfactory cut.

Silica Measurement with High Flow Rate Respirable Size Selective Samplers: A Field Study.

High and low flow rate respirable size selective samplers including the CIP10-R (10 l min(-1)), FSP10 (11.2 l min(-1)), GK2.69 (4.4 l min(-1)), 10-mm nylon (1.7 l min(-1)), and Higgins-Dewell type (2.2 l min(-1)) were compared via side-by-side sampling in workplaces for respirable crystalline silica measurement. Sampling was conducted at eight different occupational sites in the USA and five different stonemasonry sites in Ireland. A total of 536 (268 pairs) personal samples and 55 area samples were collected. Gravimetric analysis was used to determine respirable dust mass and X-ray diffraction analysis was used to determine quartz mass. Ratios of respirable dust mass concentration, quartz mass concentration, respirable dust mass, and quartz mass from high and low flow rate samplers were compared. In general, samplers did not show significant differences greater than 30% in respirable dust mass concentration and quartz mass concentration when outliers (ratio <0.3 or >3.0) were removed from the analysis. The frequency of samples above the limit of detection and limit of quantification of quartz was significantly higher for the CIP10-R and FSP10 samplers compared to low flow rate samplers, while the GK2.69 cyclone did not show significant difference from low flow rate samplers. High flow rate samplers collected significantly more respirable dust and quartz than low flow rate samplers as expected indicating that utilizing high flow rate samplers might improve precision in quartz measurement. Although the samplers did not show significant differences in respirable dust and quartz concentrations, other practical attributes might make them more or less suitable for personal sampling.

Monitoring and Statistical Evaluation of Heavy Metals in Respirable Dust in Jos Metropolitan Area, Nigeria

The concentration of heavy metals in respiration dust (˂10μg) within Jos Metropolis was monitored in seven sites made up of two industrial and high traffic areas each, with residential site as control were studied for nine consecutive months (October, 2013 to June, 2014). The concentrations of the heavy metals were studied in terms dust mass, time dependence and safety. The mass of respirable dust ranged from 0.079 0.288g, while the mean concentration ranged from 49 208ug/m. Flame Atomic Absorption Spectrometry (FAAS) analysis shows that the concentrations of heavy metals ranged from Pb, (0.016 0.331) mg/kg, Cr, (0.016 0.118)mg/kg Fe, (0.0120.652) mg/kg, ( 0.07 0.056) mg/kg, Cd, (0.002 0.107 )mg/kg, Zn, (0.0233 0.988) mg/kg, Cu, (0.023 -0.668) mg/kg and Ni (0.004 0,058) mg/kg across sites studied. The data obtained were treated statistically using one-way analysis of variance at 95% confidence limit for mean and correlated with the anthropological and industrial activities of the sites. The main sources of these heavy metals in the sampled areas, was attributed to anthropogenic activities like open incineration of waste, vehicular traffic and ongoing construction work within some of the sites.

Evaluation of Exposure Risk in the Weaving Process of MWCNT-Coated Yarn with Real-time Particle Concentration Measurements and Characterization of Dust Particles

Various applications of multiwalled carbon nanotubes (MWCNT) have been developed. One of these applications is an efficient sheet heating element that is woven from MWCNT-coated yarn. In this research, we assessed the exposure to MWCNT and/or the probability of particle release from broken MWCNT-coated yarn during the weaving process. This was accomplished using particle concentrations, microscopic observation, and carbon analysis. In the weaving process, neither an increase in the number of particles nor a difference in particle-size distribution was observed. In the scanning electron micrographic observation, nanosize MWCNT particles were not detected, but there were micron-size particles containing MWCNT as fragments of the yarn. Carbon analysis showed the concentration of micron-size particles containing MWCNT did not exceed 0.0053 mg-C/m(3) around the loom. This value was much lower than the respirable dust mass concentration. Most of micron-size particles seemed to originate from polyester yarn without MWCNT coating. It is recommended that workers use conventional (even not specialized for nanoparticles) personal protective equipment such as respirators and gloves to prevent exposure to respirable-size MWCNT-containing particles. The probability of MWCNT fall-off from the MWCNT-coated yarn was not detected by transmission electron microscopic observation of MWCNT-coated yarn before or after the weaving process.

Chamber for Testing Asbestos-Containing Products: Validation and Testing of a Re-created Chrysotile-Containing Joint Compound

Joint compound products containing chrysotile asbestos were commonly used for building construction from the late 1940s through the mid-1970s. Few relevant data exist to support reconstructing historical worker exposures to fibers generated by working with this material. Therefore, we re-created 1960s-era chrysotile-containing joint compound (JCC) and compared its characteristics to a current-day asbestos-free joint compound (JCN). Validation studies showed that a bench-scale chamber with controlled flow dynamics, designed to quantify particulate emissions from joint compound products, provided precise and reliable measurements of generated airborne dust mass, chrysotile fiber concentrations, and corresponding activity-specific emission rates. Subsequent chamber studies characterized fibers counted by phase contrast microscopy (PCM) per mass of respirable dusts and total suspended particulate dusts (total dusts), generated during JCC sanding or sweeping, as well as corresponding dust emission rates for JCC and JCN, and the ratio of total to respirable dust mass for JCN. From these data we estimated factors, F(CH-rd) and F(CH-td) (in units of f cm(-3) per mg m(-3)), by which respirable JCN dust mass concentrations collected during construction use can be converted to corresponding airborne PCM fiber concentrations generated by sanding or sweeping JCC. For sanding, median values (95% confidence limits) of F(CH-rd) and F(CH-td) were estimated to be 0.044 (0.039-0.050) and 0.212 (0.115-0.390) f cm(-3) per mg m(-3), respectively. The F(CH-td) to F(CH-rd) ratio indicates that approximately five times as many airborne PCM fibers are anticipated per unit air volume sampled when JCC dust is collected on cassettes (as done historically), than when respirable JCC dust is collected on cyclones. As the sizes of individual fibers collected appear to be primarily respirable, this difference may be a sampling artifact and suggests caution in interpreting historical fiber concentration measures made using cassettes during work with JCC-like materials. F(CH-rd) can be used with published and newly generated field measurements of respirable dust mass concentrations associated with the use of JCN or equivalent JCN materials to better characterize historical worker exposures to PCM fibers from use of JCC or equivalent JCCs. The experimental process described also can be used to develop conversion factors for other combinations of modern-day asbestos-free and historical chrysotile-containing products.

Office Environment Syndrome Study: Part II

A longitudinal self-report diary study of SBS cases and controls identified from buildingwide surveys of 4 office buildings is described. Self-report diaries were distributed to a total of 214 workers in the 4 buildings, and complete returns were obtained for 123 workers (57% return rate). Climate conditions (CO, CO2, formaldehyde, respirable dust mass (PM3.5) and particulate counts (0.3 μm, 0.5 μm, 1 μm, 5 μm), settled dust, air temperature, %RH, illuminance) were measured at each workstation. Ergonomic factors (observed work posture, office type, desk paper coverage, desk clutter, computer, mouse, keyboard tray, age of chair, chair arms, and plants, were measured at each workstation. Results showed no differences in prevailing climate conditions measured at case/control workstations. However, case reports of symptoms and environment conditions generally were worse than those for controls, and these reports showed periodicity, peaking late each day. The differences between reports by cases and controls generally remained consistent throughout the duration of the study.

Differential Pressure as a Means of Estimating Respirable Dust Mass on Collection Filters

Abstract Researchers have studied various types of respirable dust sampling filters to determine if the differential pressure across them at a constant air flow rate can be used to estimate the accumulated dust mass. Results suggest that glass fiber depth filters that allow the dust particles to penetrate well into the filter material have considerable merit. The correlation between the increase in differential pressure (AP) and dust mass (M) when using 37-mm glass fiber filters is linear, provided they are not loaded with more than approximately 5 mg of dust. Under these conditions, the relationship between differential pressure and dust mass can be described by the equation [°P(cm H2O) = 0.25 M(mg)]. Most of the data fall within ± 25 percent of a best-fit regression line and have a correlation coefficient (R2) of 0.88. These results were obtained using coal dusts from Pittsburgh, Upper Freeport, and Pocahontas seams mixed with various percentages (0 to 100%) of rock dust. The density of these dusts vari...

Pneumoconiosis in the haematite iron ore mines of West Cumbria. A study of 45 years of control.

Pneumoconiosis amongst haematite miners in West Cumbria has been studied over a 45-year period. In 1934 the disease caused the deaths of miners in early middle life from massive lung fibrosis, often complicated by tuberculosis and sometimes by carcinoma. Many more suffered from advanced emphysema and had to cease heavy face work 20 years before their time for retirement. The X-ray appearances and clinical symptoms are described. Studies have been carried out on the lung physiology and comparisons made with similar groups of South Wales coal miners. All haematite miners have been examined clinically and radiologically before admission to the industry and regular two yearly examinations by radiography have been made. Men with complicated pneumoconiosis (progressive massive fibrosis) have been withdrawn from dusty jobs and, where indicated, referred for treatment. Men with uncomplicated pneumoconiosis have been allowed to work in good conditions and have been carefully supervised. The methods of mining control are described demonstrating the changes from dense dustiness with many times the allowed limit of nitrous fumes to excellent conditions. Serial dust counts over many years have been personally undertaken, and subsequently regular estimations of mass of respirable dust per m 3 of air. The results show that there has been almost complete elimination of dust during the past 20 years. The disease has been eradicated and no miner who commenced work after 1935 has shown X-ray evidence of proved pneumoconiosis. No case has been certified by the Pneumoconiosis Panel for 17 years. Men are now fit to work at the face until retirement age, and young men are no longer aware that such a condition ever existed.

Improved pulsation dampener for respirable dust mass sampling devices.

The diaphragm- or piston-type pumps of presently available mass respirable samplers produce pulsed flow rather than a constant flow. This can be corrected by using a pulsation dampener in series with the sampling pump. A design is presented for a pulsation idampener which is highly efficient, has minimal airflow resistance, and is small enough for use with samplers presently available in the United States. Tests showed a reduction in peak-to-peak amplitude of pulsed flow to within 6% of absolute.