Ultrafine Particle Characteristics in a Rubber Manufacturing Factory
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According to epidemiological research, exposure to rubber fumes can cause various types of cancer and can lead to an increase in death rate because of cardiovascular diseases.In this study, we have assessed the characteristics of ultrafine particles emitted into the air during the manufacturing of rubber products using waste tires.To assess the aerosol distribution of rubber fumes in the workplace from a product during curing, we have performed particle number concentration mapping using a handheld condensation particle counter. The particle number concentration of each process, count median diameter (CMD), and nanoparticle ratio (<100nm) were determined using an electrical low-pressure impactor (ELPI), and the surface area concentration was determined using a surface area monitor. The shape and composition of the sampled rubber fumes were analyzed using an ELPI-transmission electron microscopy grid method. Further, the rubber fume mass concentration was determined according to the Methods for the Determination of Hazardous Substances 47/2.The results of particle mapping show that the rubber fumes were distributed throughout the air of the workplace. The concentration was the highest during the final process of the work. The particle number concentration and the surface area concentration were 545 000cm(-3) and 640 µm(2) cm(-3), respectively, approximately 10- and 4-fold higher than those in the outdoor background. During the final process, the CMD and the nanoparticle ratio were 26nm and 94%, respectively. Most of the rubber fume particles had a compact shape because of the coagulation between particles. The main components of these fumes were silicon and sulfur, and heavy metals such as zinc were detected in certain particles. The filter concentration of the rubber fumes was 0.22mg m(-3), lower than the UK workplace exposure limit of 0.6mg m(-3).Therefore, the rubber manufacturing process is a potentially dangerous process that produces a high concentration of specific nanoparticles.Keywords:
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This study investigated the relationships between particle number, surface area, and respirable mass concentration measured simultaneously in a foundry and an automotive engine machining and assembly center. Aerosol concentrations were measured throughout each plant with a condensation particle counter for number concentration, a diffusion charger for active surface area concentration, and an optical particle counter for respirable mass concentration. At selected locations, particle size distributions were characterized with the optical particle counter and an electrical low pressure impactor. Statistical analyses showed that active surface area concentration was correlated with ultrafine particle number concentration and weakly correlated with respirable mass concentration. Correlation between number and active surface area concentration was stronger during winter (R2 = 0.6 for both plants) than in the summer (R2 = 0.38 and 0.36 for the foundry and engine plant respectively). The stronger correlation in winter was attributed to use of direct-fire gas fired heaters that produced substantial numbers of ultrafine particles with a modal diameter between 0.007 and 0.023 mu m. These correlations support findings obtained through theoretical analysis. Such analysis predicts that active surface area increasingly underestimates geometric surface area with increasing particle size, particularly for particles larger than 100 nm. Thus, a stronger correlation between particle number concentration and active surface area concentration is expected in the presence of high concentrations of ultrafine particles. In general, active surface area concentration may be a concentration metric that is distinct from particle number concentration and respirable mass concentration. For future health effects or toxicological studies involving nano-materials or ultrafine aerosols, this finding needs to be considered, as exposure metrics may influence data interpretation.
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Welding generates high concentrations of ultrafine particles, which research suggests may be more toxic than larger particles. Fume characteristics were measured in a controlled apparatus as a function of voltage level and wire feed speed. Particles were sampled close to the welding process on mixed cellulose ester membrane filters and analyzed for iron, manganese, and total particulate matter at an accredited industrial hygiene laboratory. An ultrafine condensation particle counter measured the particle number concentration, and an optical particle counter measured the particle size distribution. Submicrometer particle number concentrations and iron, manganese, and total particle mass concentrations all depended on voltage levels but not on wire feed speed at a constant voltage. Ultrafine particle concentrations were more than three times greater at 23.5 V than at 16 V. Particles 0.5–0.7 μ m in diameter counted by the optical particle counter increased from 9800 particles/cm 3 at 16 V to 82,800 particles/cm 3 at 23.5 V. Manganese concentration was 1.7 mg/m 3 at 16 V vs. 6.4 mg/m 3 at 23.5 V. The data suggest that welders should use lower voltage levels whenever possible.
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Four edible oils and five oil-water ratios were heated to investigate the effect of water on the particle emission characteristics of particles emitted from heated cooking oil. PM2.5 and particles ranging from 0.01–10 μm emitted during oil-water heating were monitored via a DustTrak, a condensation particle counter and an aerodynamic particle sizer. The results showed that the PM2.5 levels and the particle number concentrations of the series of corn or peanut oil-water emulsions could be up to 6 and 50 times higher, respectively, than those of the series of soybean or canola oil-water emulsions. All heated oil-water emulsions at an oil-water ratio of 6-1 generated higher total particle concentrations than those of other ratios. The promoting factors (normalized by the corresponding oil volume to total volume) for the concentration of ultrafine particles, PM1 and PM2.5 ranging from 1.20 to 3.32, 1.14 to 2.50 and 0.71 to 2.14, respectively. In addition, the ratio of ultrafine particles (10–100 nm) to total particles and the particle number mode and median diameters changed with the oil-water ratio, but no obvious trend was observed. The regression results showed that the impact of water on particle emissions is not statistically significant.
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Very fine particle number and mass concentrations were mapped in an engine machining and assembly facility in the winter and summer. A condensation particle counter (CPC) was used to measure particle number concentrations in the 0.01 microm to 1 microm range, and an optical particle counter (OPC) was used to measure particle number concentrations in 15 channels between 0.3 microm and 20 microm. The OPC measurements were used to estimate the respirable mass concentration. Very fine particle number concentrations were estimated by subtracting the OPC particle number concentrations from 0.3 microm to 1 microm from the CPC number concentrations. At specific locations during the summer visit, an electrical low pressure impactor was used to measure particle size distribution from 0.07 microm to 10 microm in 12 channels. The geometric mean ratio of respirable mass concentration estimated from the OPC to the gravimetrically measured mass concentration was 0.66 with a geometric standard deviation of 1.5. Very fine particle number concentrations in winter were substantially greater where direct-fire natural gas heaters were operated (7.5 x 10(5) particles/cm(3)) than where steam was used for heat (3 x 10(5) particles/cm(3)). During summer when heaters were off, the very fine particle number concentrations were below 10(5) particles/cm(3), regardless of location. Elevated very fine particle number concentrations were associated with machining operations with poor enclosures. Whereas respirable mass concentrations did not vary noticeably with season, they were greater in areas with poorly fitting enclosures (0.12 mg/m(3)) than in areas where state-of-the-art enclosures were used (0.03 mg/m(3)). These differences were attributed to metalworking fluid mist that escaped from poorly fitting enclosures. Particles generated from direct-fire natural gas heater operation were very small, with a number size distribution modal diameter of less than 0.023 microm. Aerosols generated by machining operations had number size distributions modes in the 0.023 microm to 0.1 microm range. However, multiple modes in the mass size distributions estimated from OPC measurements occurred in the 2-20 microm range. Although elevated, very fine particle concentrations and respirable mass concentrations were both associated with poorly enclosed machining operations; the operation of the direct-fire natural gas heaters resulted in the greatest very fine particle concentrations without elevating the respirable mass concentration. These results suggest that respirable mass concentration may not be an adequate indicator for very fine particle exposure.
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Agglomerated and nonagglomerated SiO₂ particles are synthesized in furnace by the vapor feeding method
for the test particle generator this study. These polydispersed particles are classified with DMA to extract
equal mobility particles. Then these particles are introduced into Thermal Precipitator through the
ESP(Electrostatic Precipitator) to see the thermophoretic particle deposition using CNCs(Condensation Nuclei
Counter). The efficiency of thermophoretic particle deposition according to agglomerated and nonagglomerated
particles in Thermal precipitator has been studied as a function of particle size and TEOS mole
concentration using monodisperse particles classified by DMA. The results show that the particle deposition
efficiency decreases as TEOS mole concentration increases and particle size increases. Therefore, it is
concluded that the thermophoretic deposition efficiency is dependent of the particle morphology.
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The main performance characteristics of the modernized condensation particle counter (CPC) UF-02M were determined. We studied the particle number concentration range of the instrument and the detection efficiency as a function of the particle diameter experimentally. In order to determine a cut-size D50, the function was fitted to the experimental data. According to the fitting, the cut-size was 4.35 nm. The determined cut-size allows detecting the aerosol particles of the nucleation mode, giving possibilities to find many applications of the CPC UF-02M in the investigations of the aerosol nanometre particle dynamical properties. The counting efficiency of the CPC at high particle concentrations was experimentally investigated using silver particles of a 20 nm diameter. The minimum measured number concentration of aerosol particles was 0.003 cm–3, the maximum was 150000 cm-3 with the accuracy of 20%. The operation of the CPC UF-02M was compared with the operation of a commercially available SMPS TSI3936 under ambient conditions. The measured number concentrations were comparable with 5% accuracy. During the testing time, both instruments detected a new particle formation event. It was determined that the number concentration measured with the modernized CPC was higher than that determined by the SMPS. It was explained that a new CPC had a lower cut-size and detected smaller particles than the SMPS did.
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