MCE Filter Research Articles

Oznaczanie antymonu i jego związków w powietrzu na stanowiskach pracy

Antimony is used as an additive in font and bearing alloys along with other metals. Antimony in metallic form is not classified as a health hazard, while its salts have been so classified. Some antimony compounds have been classified as carcinogens. The applicable value of the maximum allowable concentration (MAC) in air at workplaces is 0.5 mg/m3 (MRPiPS ordinance, 2018). The purpose of this study was to develop a method for the determination of antimony for occupational exposure assessment in the range of 1/10–2 of the proposed MAC values. The method consists of collecting antimony and its airborne compounds from an MCE filter, mineralizing the filter in aqua regia at 150°C, then determining the antimony content in the sample using atomic absorption spectrometry (AAS) with flame atomization. The method for the determination of antimony is presented in the form of an analytical procedure, which is included in the appendix. The scope of the article includes health and environmental health and safety issues that are the subject of research in health sciences and environmental engineering

Assessment of Particulate and Gaseous Fluoride in Phosphate Fertilizer Industry

Fluorides are emitted in both gaseous and particle forms in the industrial sector. However, studies usually only report total fluoride content. Therefore, the study aimed to assess the particulate, gaseous fluoride and correlate it with the respirable dust particles in Single Super Phosphate (SSP), Granular Single Super Phosphate (GSSP), and administration divisions of the industry. Respirable dust particles, particulate fluoride, and hydrogen fluoride in the work environment were collected on a filter cassette containing an MCE filter paper (0.8 micron 37-mm) and Na2CO3 impregnated backup pad, respectively, using a personal sampler. The fluoride samples were analyzed using Ion Selective Electrode (ISE) and expressed as milligrams per meter cube (mg.m-3). The respirable dust, particulate, and gaseous fluoride content were found to have statistically significant differences (p<0.001) between the divisions (SSP, GSSP, and administration) in the static monitoring, whereas, in the case of personal monitoring, no significant differences were observed. Average airborne respirable, particulate, and gaseous fluoride levels in static monitoring were 1.37, 1.03, 0.20 mg.m-3, 0.018, 0.008, 0.001 mg.m-3, and 0.808, 0.403, 0.026 ppm in SSP, GSSP and administration respectively, whereas in personal monitoring the average respirable, particulate and gaseous fluoride concentrations were 1.18, 0.85, 0.30 mg.m-3, 0.0013, 0.007, 0.002 mg.m-3 and 0.356, 0.258, 0.011 ppm in SSP, GSSP and administration respectively. The present study observed that the levels of fluoride decreased with an increase in distance from SSP, followed by GSSP and administration. It indicates that the fluoride exposure was inversely proportional to the distance of the source. This study outcome will help to design a policy and intervention to mitigate fluoride exposure among workers.

83 Development of a New Xrd Method to Evaluate Exposure to Respirable TiO2 in Workplace Air

Abstract ECHA classified TiO2 particles with an aerodynamic diameter ≤10 μm as carcinogen. Although the OELV for TiO2 is still related to inhalable particles in many jurisdictions, NIOSH recommended a REL of 2.4 mg/m3 for fine TiO2, and 0.3 mg/m3 for ultrafine TiO2. The latter implies the development of a more robust method for measuring TiO2 in workplace air. X-ray diffraction (XRD) is a powerful laboratory method for quantifying crystalline matter and is frequently used to measure respirable crystalline silica in workplaces. Rutile and anatase powders were obtained from a commercial vendor and a size fraction smaller than 10 µm was separated from these powders and used to prepare a calibration series in a calm-air dust chamber. The methodology for quantifying the rutile or anatase is performed as described in ISO 16258-1:2015 for measuring respirable crystalline silica. The limit of detection and quantification (LOD/LOQ) were for rutile 0.8/1.4 µg and anatase 0.6/1.1 µg, respectively. From these measurements, we conclude that direct on filter XRD is a powerful method for analyzing respirable TiO2 samples. Further validation of the XRD method was performed by comparing the results of 177 respirable personal samples collected on 25 mm MCE filters using Casella-HD cyclone samplers at nine TiO2 production plants with ICP-MS data gained from the same samples. Excellent correlations were obtained between the XRD and ICP-MS data for each sampling site but observed consistent site-dependent deviations explained by differences in crystallinity of the TiO2 phases and the presence of titanium-containing minerals other than rutile and anatase.

Quantitative measurements of capillary absorption in thin porous media by the Automatic Scanning Absorptometer

A 1D model based on Darcy’s law is proposed to allow quantitative measurements of the penetration depth of water-glycerol-hexanediol mixtures in thin porous media using an Automatic Scanning Absorptometer (ASA). The limitations of this 1D model are discussed with respect to the nozzle dimensions and the liquid penetration depth. The penetration depth scales with liquid (viscosity and surface tension (η, σ)) and media parameters (average pore radius (r)) as predicted by Darcy’s law for Al2O3 disks that are inert to the liquid components. The penetration dynamics in PVDF and MCE filter membranes show a deviation from Darcy’s law, indicating specific liquid – media interaction with at least one of the liquid components. Furthermore a linear time regime is observed in the early stages of liquid penetration for time scales much larger than for which inertia effects are expected. This can on the one hand indicate that either, the liquid does not move into the fibrous samples as a homogenous liquid, or that the porous material deforms during the liquid imbibition process. On the other hand, it could be an effect resulting from the complexity of the porous structure itself and an indication of surface film flow formation.

An examination of MCE filter morphology and implications on preparation and analysis of air samples for asbestos

ABSTRACTMorphological imperfections of mixed-cellulose ester filters and their possible influence on sample preparation and analysis of asbestos were examined. Filters were identified with large regions of non-porous “dead zones” which could negatively affect fiber deposition and, therefore, fiber recovery and analysis by Transmission Electron Microscopy (TEM). As these imperfections are effectively erased during the preparation of the sample, they may not be readily observed by TEM. Un-collapsed filters as well as those collapsed using dimethylformamide (DMF) and two acetone techniques were examined. In order to minimize negative sampling and analytical bias, it is suggested that MCE samples be collapsed utilizing a 35% DMF solution, etched with a correctly calibrated low-temperature etcher, carbon coated using a rotating and tilted stage, and analyzed with a strong analyst-independent grid square opening randomization scheme.

The verification methods for the extraction of thoracic fraction sulfuric acid(VI) and validation the ion chromatography method

Sulfuic acid is widely used in many industries, which is associated with the exposure of a large group of employees to this harmful substance. In 2012, a new value of occupational exposure limit for sulfuric acid as the thoracic fraction was introduced in Poland. Due to this change, the method enabling determination of sulfuric acid in the thoracic fraction has been established in accordance with the requirements of the Standard No. EN 481. The practical use of this method indicated the necessity of modificating the procedure for sulfuric acid extraction from methylcellulose filters. The aim of this study was to modify the extraction method of sulfuric acid(VI) and to validate the ion chromatography method. The determination of sulfuric acid(VI) with ion chromatography with conductivity detection was applied in this study. The study used an analytical column IonPac® Dionex AS22 (4 × 250 mm) with a precolumn Dionex IonPac AG22 (4 × 50mm) and a mixture of carbonate and bicarbonate, as a carrier phase of an isocratic flow rate 1.2 ml/min. The proposed conditions for the chromatographic separation of ions enabled the determination of sulfuric acid (VI) in the presence of fluoride ions, acetate, chloride, bromide, nitrate, nitrite and phosphate. Parallel Particle Impactors (PPI) with mixed cellulose filter dedicated for thoracic fraction was used for sampling. The determination method was achieved at 2.125 μg/m3 for 480 m3 of air and extraction of MCE filter with water (10 ml). The detection limit calculated on the basis of the signal-to-noise ratio was 1.9 ng, and the limit of quantification was 5.7 ng. The uncertainty of the overall method is 11% and 23% of expanded uncertainty. PPI sampler dedicated to collect thoracic fractions has been tested in real conditions in factories producing and processing sulfuric acid. The method of vacuum filtration for sulfates extraction from filters MCE, which was published in The Principles and “Methods of Assessing the Working Environment” (PiMOŚP), was modified. The use of a mechanical shaking MCE filter with ultrapure water Milli-Q for 30 min enabled to receive approximately 100% recovery of sulfuric acid from the filter analyzed while avoiding the leaching of interferents. The results confirmed the presence of sulfuric acid(VI) in the thoracic fraction of aerosol tested at concentrations ranging from 0.03 to 1.47 MAC value.

Determination method of iron and its inorganic oxide in the air of workplace

Objective: To establish the method for determination of iron and its inorganic oxide in the air of workplace. Methods: The iron and its inorganic oxide was collected by MCE filter membrane and then digested by electric heating digestion apparatus. Atomic absorption spectrophotometer (AAS) or inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the detection of iron and its inorganic oxide. Results: The sampling efficiency was higher than 97%; under the 372.0 nm wavelength, the linearity of AAS was good at the range of 1.0~150.0 μg/ml, the minimum quantitation concentration was 0.28 mg/m(3), the maximum quantitation concentration was 6.24 mg/m(3), the recovery was ranged from 99%~102%, the RSD of intra-and inter-batch precision were 0.5%~1.2% and 1.0%~2.2%, respectively; the linearity of ICP-OES was good at the range of 0.1~500 μg/ml, the minimum quantitation concentration was 0.28 mg/m(3), the maximum quantitation concentration was 20.8 mg/m(3), the recovery was ranged from 101%~103%, the RSD of intra-and inter-batch precision were 0.5%~1.0% and 1.5%~1.6%, respectively. Conclusion: The sampling method and determination method meet the requirements of analysis and apply to the collection and determination of iron and its inorganic oxide in the air of workplace.

Assessment of Bioaerosol Distributions in Municipal Solid Waste Transfer Station

Operations in municipal solid waste (MSW) management chain are known to generate air pollution, especially with particulate matter. A significant portion of such pollution consists of bioaerosol particles, which potentially are harmful to human health. The presented research has aimed at assessing the emissions and seasonal fluctuations of total particulate matter and bioaerosol generated in MSW transfer facility. Aerosol samples have been collected every two weeks during the warm period of July and September. The samples have been collected by Button sampler on MCE filters. The concentration of total viable microorganisms has been determined by cultivation on Plate Count Agar. It was found that in the immediate vicinity of waste loading operations, the concentration of colony-forming microorganisms has reached 10 5 CFU/m3, while outside the building, the concentration has decreased by a factor of ~10. Both particle and microorganisms concentration indoor/outdoor ratio has revealed high relationship indicating similar transfer mechanisms of particles to the outdoor environment.

Air sampling filtration media: Collection efficiency for respirable size-selective sampling.

The collection efficiencies of commonly used membrane air sampling filters in the ultrafine particle size range were investigated. Mixed cellulose ester (MCE; 0.45, 0.8, 1.2, and 5 μm pore sizes), polycarbonate (0.4, 0.8, 2, and 5 μm pore sizes), polytetrafluoroethylene (PTFE; 0.45, 1, 2, and 5 μm pore sizes), polyvinyl chloride (PVC; 0.8 and 5 μm pore sizes), and silver membrane (0.45, 0.8, 1.2, and 5 μm pore sizes) filters were exposed to polydisperse sodium chloride (NaCl) particles in the size range of 10-400 nm. Test aerosols were nebulized and introduced into a calm air chamber through a diffusion dryer and aerosol neutralizer. The testing filters (37 mm diameter) were mounted in a conductive polypropylene filter-holder (cassette) within a metal testing tube. The experiments were conducted at flow rates between 1.7 and 11.2 l min-1. The particle size distributions of NaCl challenge aerosol were measured upstream and downstream of the test filters by a scanning mobility particle sizer (SMPS). Three different filters of each type with at least three repetitions for each pore size were tested. In general, the collection efficiency varied with airflow, pore size, and sampling duration. In addition, both collection efficiency and pressure drop increased with decreased pore size and increased sampling flow rate, but they differed among filter types and manufacturer. The present study confirmed that the MCE, PTFE, and PVC filters have a relatively high collection efficiency for challenge particles much smaller than their nominal pore size and are considerably more efficient than polycarbonate and silver membrane filters, especially at larger nominal pore sizes.

Trivalent chromium solubility and its influence on quantification of hexavalent chromium in ambient particulate matter using EPA method 6800

Measurement of carcinogenic Cr(VI) in ambient PM is challenging due to potential errors associated with conversion between Cr(VI) (a carcinogen) and Cr(III) (an essential nutrient). Cr(III) conversion is a particular concern due to its >80% atomic abundance in total Cr. U.S. Environmental Protection Agency (EPA) method 6800 that uses water-soluble isotope spikes can be used to correct the interconversion. However, whether the enriched Cr(III) isotope spikes can adequately mimic the Cr(III) species originally in ambient PM is unknown. This study examined the water solubility of Cr(III) in ambient PM and discussed its influence on Cr(VI) measurement. Ambient PM10 samples were collected on Teflon filters at four sites in New Jersey that may have different Cr emission sources. The samples were ultrasonically extracted with 5 mL DI-H2O (pH 5.7) at room temperature for 40 min, and then analyzed by ion chromatography–inductively coupled plasma mass spectrometry (IC-ICPMS). Cr(III) was below detection limit (0.06 ng/m3) for all samples, suggesting water-soluble Cr(III) species, such as CrCl3, Cr(NO3)3, and amorphous Cr(OH)3, in the ambient PM were negligible. Therefore, the enriched 50Cr(III) isotope spike (in the form of Cr(NO3)3) could not mimic the original ambient Cr(III). Only the conversion of 53Cr(VI) (in the form of K2CrO4) was taken into account when correcting the interconversion. We then used NaHCO3-pretreated MCE filters (prespiked with enriched isotope species) to measure Cr(VI) in the ambient PM10. The samples were ultrasonically extracted at 60 C pH 9 solutions for 40 min followed by IC-ICPMS analysis. Due to the correction of Cr(VI) reduction, the Cr(VI) concentrations determined by EPA method 6800, 0.26 ± 0.16 (summer) and 0.16 ± 0.11(winter) ng/m3 (n = 64), were significantly greater than those by the external standard curve, 0.21 ± 0.17 (summer) and 0.10 ± 0.07 (winter) ng/m3 (n = 56) (p < 0.01, Student’s t-test). Our study revealed that appropriate application of EPA method 6800 is important because it only applies to soluble fraction of Cr species in ambient PM.ImplicationsAccurate measurement of carcinogenic Cr(VI) in ambient PM is challenging due to conversion between Cr(VI) (a human carcinogen) and Cr(III) (a human essential nutrient). The conversion of Cr(III) is of particular concern due to its dominant presence in total Cr (>80%). This study examined the water solubility of Cr(III) in ambient PM that was collected at four locations in New Jersey. Then we discussed the influence of Cr(III) solubility on the application of EPA method 6800, which utilizes enriched isotope spikes to correct the interconversion. Our results suggested that appropriate application of EPA method 6800 is important because it only applies to soluble fraction of Cr species.

Interconversion of Chromium Species During Air Sampling: Effects of O3, NO2, SO2, Particle Matrices, Temperature, and Humidity

The interconversion between Cr(VI), a pulmonary carcinogen, and Cr(III), an essential human nutrient, poses challenges to the measurement of Cr(VI) in airborne particles. Chamber and field tests were conducted to identify the factors affecting Cr(VI)-Cr(III) interconversion in the basic filter medium under typical sampling conditions. In the chamber tests, isotopically enriched (53)Cr(VI) and (50)Cr(III) were spiked on diesel particulate matter (DPM) and secondary organic aerosol (SOA) that were precollected on a basic MCE filter. The filter samples were then exposed to clean air or the air containing SO2 (50 and 160 ppb), 100 ppb O3, or 150 ppb NO2 for 24 h at 16.7 LPM flow rate at designated temperature (20 and 31 °C) and RH (40% and 70%) conditions. Exposure to 160 ppb SO2 had the greatest effect on (53)Cr(VI) reduction, with (53)Cr(VI) recovery of 31.7 ± 15.8% (DPM) and 42.0 ± 7.9% (SOA). DPM and SOA matrix induced (53)Cr(VI) reduction when exposed to clean air while reactive oxygen species in SOA could promote (50)Cr(III) oxidation. Deliquescence when RH increased from 40% to 70% led to conversion of Cr(III) in SOA, whereas oxidized organics in DPM and SOA enhanced hygroscopicity and thus facilitated Cr(VI) reduction. Field tests showed seasonal variation of Cr(VI)-Cr(III) interconversion during sampling. Correction of the interconversion using USEPA method 6800 is recommended to improve accuracy of ambient Cr(VI) measurements.

Pre-sampling contamination of filters used in measurements of airborne (1 → 3)-β-d-glucan based on glucan-specific Limulus amebocyte lysate assay

Air sampling for (1 → 3)-β-D-glucan may be a good method for assessing inhalation exposure to airborne fungi. Pre-sampling contamination of filter media used for sampling (1 → 3)-β-D-glucan may lead to substantial exposure measurement errors. Using the Limulus amebocyte lysate assay, we tested for pre-sampling levels of (1 → 3)-β-D-glucan on three types of filters-mixed cellulose ester (MCE)[1 brand], glass fiber (GF)[1 brand], and polycarbonate (PC)[5 brands]. Levels of (1 → 3)-β-D-glucan on MCE filters exceeded 4586.1 pg per filter. Levels on GF filters averaged 135.3 (± 28.9) pg per filter (range = 94.8-160.4 pg per filter) and levels on PC filters averaged 152.4 (± 236.1) pg per filter (range = non-detectable-1760.7 pg per filter). Efforts to clean MCE and GF filters were unfeasible or unsuccessful. Sonicating PC filters for two hours in ethanol, followed by a wash in pyrogen-free water, effectively eliminated measured levels of (1 → 3)-β-D-glucan on four brands of PC filters, as compared to untreated PC filters. This pretreatment process did not appear to physically damage the PC filters. Air sampling results highlighted the potentially problematic contamination of untreated PC filters. Ensuring that sampling media are free of (1 → 3)-β-D-glucan before sampling is crucial to accurately measure levels of (1 → 3)-β-D-glucan exposure, especially in environments where levels of (1 → 3)-β-D-glucan are low.

Efficiency of Sampling and Analysis of Asbestos Fibers on Filter Media: Implications for Exposure Assessment

To measure airborne asbestos and other fibers, an air sample must represent the actual number and size of fibers. Typically, mixed cellulose ester (MCE, 0.45 or 0.8 μm pore size) and, to a much lesser extent, capillary-pore polycarbonate (PC, 0.4 μm pore size) membrane filters are used to collect airborne asbestos for count measurement and fiber size analysis. In this research study, chrysotile asbestos (fibers both shorter and longer than 5 μm) were generated in an aerosol chamber and sampled by 25 mm diameter MCE filter media to compare the fiber retention efficiency of 0.45 μm pore size filters vs. 0.8 μm pore size filter media. In addition, the effect of plasma etching times on fiber densities was evaluated. This study demonstrated a significant difference in fiber retention efficiency between 0.45 μm and 0.8 μm pore size MCE filters for asbestos aerosols (structures longer than or equal to 0.5 μm length). The fiber retention efficiency of a 0.45 μm pore size MCE filter is statistically significantly higher than that of the 0.8 μm pore size MCE filter. However, for asbestos structures longer than 5μm, there is no statistically significant difference between the fiber retention efficiencies of the 0.45 μm and 0.8 μm pore size MCE filters. The mean density of asbestos fibers (longer than or equal to 0.5 μm) increased with etching time. Doubling the etching time increased the asbestos filter loading in this study by an average of 13%. The amount of plasma etching time had no effect on the filter loading for fibers longer than 5 μm. Many asbestos exposure risk models attribute health effects to fibers longer than 5 μm. In these models, both the 0.45 μm and 0.8 μm pore size MCE filter can produce suitable estimates of the airborne asbestos concentrations. However, some models suggest a more significant role for asbestos fibers shorter than 5 μm. Exposure monitoring for these models should consider only the 0.45 μm pore size MCE filters as recommended by the U.S. Environmental Protection Agency Asbestos Hazard Emergency Response Act (AHERA) protocol and other methods.

The effect of environmental conditions and electrical charge on the weighing accuracy of different filter materials

Different filter materials and electrical charge elimination methods were used to investigate the weighing accuracy of filter papers under different environmental conditions. The results show that the standard deviations (S.D.) of weight data for glass fiber and MCE filters were substantial without environmental control, whether or not the electrical charge eliminators were used. Values of 0.157 and 0.349 mg were determined for glass and MCE filters, respectively. The accuracy of weighing was substantially improved and the S.D. was reduced to 0.01 and 0.09 mg for glass fiber and MCE filters, respectively, after applying the environmental control conditions. For PVC and Teflon filters, the accuracy of weighing was good, even in the uncontrolled environmental conditions, whether or not the electrical charge eliminators were used. The S.D. values of weighing data of PVC and Teflon filters were 0.007 and 0.011 mg, respectively.