Airborne Particle Emissions Research Articles

Towards a test stand for standardized measurements of the brake emissions

Brake-related particulate matter contributes considerably to the non-exhaust emissions of the transport sector in urban areas of the world. The airborne particle emissions from automotive brakes currently lack any proper regulations. Future regulations require test stands, test cycles and particle instruments to be suitable for measuring the brake emissions. This present work focuses on the design of a novel test stand for reliable measurements of the brake emissions with a high sampling efficiency. A test stand in the form of an inertial disc brake dynamometer was redesigned to allow control of the cleanness of the incoming air and to assure isokinetic sampling. The cleanness of the incoming air, together with an over-pressurized chamber around the brake assembly, ensures that all the particles measured originate from the brake materials. In order to evaluate the novel design, the number and size distributions of the brake emissions are measured online with and without control of the cleanness of the intake air. The results reveal that this test stand can be proposed as a standard test stand to assess objectively the emissions of airborne brake particles in future regulations.

Airborne particle emission of a commercial 3D printer: the effect of filament material and printing temperature.

The knowledge of exposure to the airborne particle emitted from three-dimensional (3D) printing activities is becoming a crucial issue due to the relevant spreading of such devices in recent years. To this end, a low-cost desktop 3D printer based on fused deposition modeling (FDM) principle was used. Particle number, alveolar-deposited surface area, and mass concentrations were measured continuously during printing processes to evaluate particle emission rates (ERs) and factors. Particle number distribution measurements were also performed to characterize the size of the emitted particles. Ten different materials and different extrusion temperatures were considered in the survey. Results showed that all the investigated materials emit particles in the ultrafine range (with a mode in the 10-30-nm range), whereas no emission of super-micron particles was detected for all the materials under investigation. The emission was affected strongly by the extrusion temperature. In fact, the ERs increase as the extrusion temperature increases. Emission rates up to 1×1012 particlesmin-1 were calculated. Such high ERs were estimated to cause large alveolar surface area dose in workers when 3D activities run. In fact, a 40-min-long 3D printing was found to cause doses up to 200mm2 .

A Study on Emission of Airborne Wear Particles from Car Brake Friction Pairs

The emission of airborne wear particles from friction material / cast iron pairs used in car brakes was investigated, paying special attention to the influence of temperature. Five low-metallic mat ...

A field study of airborne particle emissions from automotive disc brakes

Airborne particle emissions from automotive disc brakes, one of the main sources of urban particulate matter, adversely affect health. Field measurement of brake particles is complicated, as various particle sources (such as tailpipe emissions, resuspended road dust and tyre wear) can interfere. Brake particles are usually measured on dyno benches or in model-scale tests in controlled environments. Such test results need confirmation in the field, where air flow around disc brakes differs completely. Few field studies focusing on disc brake particles have been reported in the literature. The objective of this work is to investigate further the possibility of measuring brake particles in the field using particle instruments mounted on a car. A car was instrumented with two GRIMM 1.109 aerosol spectrometers and two TSI DustTrak 8520 aerosol monitors. One GRIMM spectrometer and one TSI DustTrak monitor recorded data near the brake, and the other GRIMM spectrometer and the other TSI DustTrak monitor recorded data at the front of the car during five field tests in outer Stockholm. The results suggest that braking directly correlates with increased particle concentrations measured near the brake. The reported test stand results correlate with the field-measured number distributions.

Geogenic versus anthropogenic geochemical influence on trace elements contents in soils from the Milazzo Peninsula

Milazzo Peninsula soils and substrates are extremely variable, composed of acidic, mafic and ultramafic metamorphic rocks, carbonatic sedimentary rocks, and sometimes volcanic rocks, thus contributing to a mixed influence on their chemical composition. Moreover, the region is highly polluted due to atmospheric releases from anthropogenic activities, such as refinery industry. In addition, emissions of airborne particles from volcanic eruptions are also likely to fall to the ground and provide trace elements to the soils. The purpose of this study is to distinguish between anthropogenic and geogenic sources contributing to the concentrations of metals in soils by studying their distribution in major and trace elements in relation to substrates. As regards geogenic sources, the major elements composition of soils comes firstly from metamorphic rocks, secondly from carbonates, and to a minor extent from volcanic rocks. Enrichment factors calculations relative to substrate rocks, and using Th as reference element, show that the soils are enriched in As, Pb, Zn, and Ni. Rare earth elements (REEs) patterns normalized to substrate rocks exhibit enrichment in light REEs and a positive anomaly in Gd, indicating anthropogenic contributions in the soil composition. REE ratios and trace elements were plotted to investigate the relationships between anthropogenic sources and substrates in soils compositions. The graphs of La/Ni vs La/Gd and La/Ce vs La/Nd show that soils plot on a line toward substrate rocks on one side, and toward an end member which is represented by a spent catalyst and atmospheric particles emitted by refinery activities. Plots of La vs Cr, and V vs La show similar trends, whereas plots of Zn vs Ni and Pb vs V suggest that another end member, which is unidentified, contributes to soil enrichment in Zn and Pb. A binary mixing model applied to the most Zn enriched soil suggests that anthropogenic inputs from refinery emissions may have contributed to 16% of the anomalies in La/Gd. These results suggest that the trace element composition of Milazzo's peninsula soils partly bears the signature of atmospheric emissions of the refinery.

Characterization of airborne particles generated from metal active gas welding process

This study is focused on the characterization of particles emitted in the metal active gas welding of carbon steel using mixture of Ar + CO2, and intends to analyze which are the main process parameters that influence the emission itself. It was found that the amount of emitted particles (measured by particle number and alveolar deposited surface area) are clearly dependent on the distance to the welding front and also on the main welding parameters, namely the current intensity and heat input in the welding process. The emission of airborne fine particles seems to increase with the current intensity as fume-formation rate does. When comparing the tested gas mixtures, higher emissions are observed for more oxidant mixtures, that is, mixtures with higher CO2 content, which result in higher arc stability. These mixtures originate higher concentrations of fine particles (as measured by number of particles by cm3 of air) and higher values of alveolar deposited surface area of particles, thus resulting in a more severe worker's exposure.

Evaluation of airborne particle emissions from commercial products containing carbon nanotubes

The emission of the airborne particles from epoxy resin test sticks with different CNT loadings and two commercial products were characterized while sanding with three grit sizes and three disc sander speeds. The total number concentrations, respirable mass concentrations, and particle size number/mass distributions of the emitted particles were measured using a condensation particle counter, an optical particle counter, and a scanning mobility particle sizer. The emitted particles were sampled on a polycarbonate filter and analyzed using electron microscopy. The highest number concentrations (arithmetic mean = 4670 particles/cm(3)) were produced with coarse sandpaper, 2% (by weight) CNT test sticks and medium disc sander speed, whereas the lowest number concentrations (arithmetic mean = 92 particles/cm(3)) were produced with medium sandpaper, 2% CNT test sticks and slow disc sander speed. Respirable mass concentrations were highest (arithmetic mean = 1.01 mg/m(3)) for fine sandpaper, 2% CNT test sticks and medium disc sander speed and lowest (arithmetic mean = 0.20 mg/m(3)) for medium sandpaper, 0% CNT test sticks and medium disc sander speed. For CNT-epoxy samples, airborne particles were primarily micrometer-sized epoxy cores with CNT protrusions. No free CNTs were observed in airborne samples, except for tests conducted with 4% CNT epoxy. The number concentration, mass concentration, and size distribution of airborne particles generated when products containing CNTs are sanded depends on the conditions of sanding and the characteristics of the material being sanded.

Aerosols emitted by the combustion of polymers containing nanoparticles

The fire behavior and the characterization of solid and gaseous fire effluents of polymers [polymethyl methacrylate (PMMA) and polyamide-6 (PA-6)] filled with nanoparticles (silica, alumina, and carbon nanotubes) used to improve their flame retardancy were investigated. To determine the impact of these composites on the emission of airborne particles produced during their combustion in accidental fire scenarios, an experimental setup was developed to measure the mass distribution in the 30 nm–10 μm range, and the concentrations of submicrometric particles in the aerosol. Comparisons were made between unfilled and filled polymers, and the influence of filler surface treatments (silane-based), as well as combinations with a flame retardant [ammonium polyphosphate (APP)], was investigated. The presence of nano-oxides in PMMA shows a significant effect on the rate of particle emission with a decrease in the concentration of the emitted submicrometric particles. APP in PMMA led to a decrease in the mass fraction of ultrafine particles and an increase in the rate of submicrometric particle emission compared to filled compositions with nano-oxides. Atomic force microscopy was used as a complementary tool for the characterization of the particles emitted during combustion, allowing direct observation of nanoparticle morphology, detection of carbon nanotubes in the aerosol, and visualization of the effect of APP on nanoparticle morphology.

A pin-on-disc study of the rate of airborne wear particle emissions from railway braking materials

The current study investigates the characteristics of particles generated from the wear of braking materials, and provides an applicable index for measuring and comparing wear particle emissions. A pin-on-disc tribometer equipped with particle measurement instruments was used. The number concentration, size, morphology, and mass concentration of generated particles were investigated and reported for particles 10nm–32μm in diameter. The particles were also collected on filters and investigated using EDS and SEM. The effects of wear mechanisms on particle morphology and changes in particle concentration are discussed. A new index, the airborne wear particle emission rate (AWPER), is suggested that could be used in legislation to control non-exhaust emissions from transport modes, particularly rail transport.

Silver Nanoparticles and Total Aerosols Emitted by Nanotechnology-Related Consumer Spray Products

Products containing silver nanoparticles are entering the market rapidly, but little is known about the potential for inhalation exposure to nanosilver. The objectives of this work were to characterize the emissions of airborne particles from consumer products that claim to contain silver nanoparticles or ions, determine the relationship between emissions and the products' liquid characteristics, and assess the potential for inhalation exposure to silver during product use. Three products were investigated: an antiodor spray for hunters, a surface disinfectant, and a throat spray. Products emitted 0.24-56 ng of silver in aerosols per spray action. The plurality of silver was found in aerosols 1-2.5 μm in diameter for two products. Both the products' liquid characteristics and the bottles' spray mechanisms played roles in determining the size distribution of total aerosols, and the size of silver-containing aerosols emitted by the products was largely independent of the silver size distributions in the liquid phase. Silver was associated with chlorine in most samples. Results demonstrate that the normal use of silver-containing spray products carries the potential for inhalation of silver-containing aerosols. Exposure modeling suggests that up to 70 ng of silver may deposit in the respiratory tract during product use.

Characterization of aerosol emitted by the combustion of nanocomposites

Day after day, new applications using nanoparticles appear in industry, increasing the probability to find these particles in the workplace as well as in ambient air. As epidemiological studies have shown an association between increased particulate air pollution and adverse health effects in susceptible members of the population, it is particularly important to characterize aerosols emitted by different sources of emission, during the combustion of composites charged with nanoparticles for example. The present study is led in the framework of the NANOFEU project, supported by the French Research Agency (ANR), in order to characterize the fire behaviour of polymers charged with suitable nanoparticles and make an alternative to retardant systems usually employed. To determine the impact of these composites on the emission of airborne particles produced during their combustions, an experimental setup has been developed to measure the mass distribution in the range of 30 nm – 10 μm and the number concentration of submicrometric particles of the produced aerosol. A comparison is performed on the aerosol emitted during the combustion of several polymers alone (PMMA, PA-6), polymers containing nanofillers (silica, alumina, and carbon nanotubes) and polymers containing both nanofillers and a conventional flame retardant system (ammonium polyphosphate). The results on the morphology of particles were also investigated using AFM.

Parameter study of microdroplet formation by impact of millimetre-size droplets onto a liquid film

The objective of this work is to carry out an experimental investigation on the influence of different parameters such as liquid properties (viscosity and liquid–gas surface tension), impacting droplet properties (velocity v i and diameter d i ) and the thickness of liquid film on the emission of airborne particles produced by the impact of millimetre-size droplets onto a liquid film. Our results show that in the variation range studied, the increase of v i and d i or the decrease in liquid film thickness produces an increase in the mean number of microdroplets emitted by impact in the size range 2–50 μm. Furthermore, it was also observed that an increase in viscosity involves a steep decrease in the mean number of microdroplets emitted. These microdroplets may be produced by the fingers pinching of the crown formed during impact. In the case of low surface tension liquid, the formation of bubbles involves high production of droplets smaller than 15 μm. The results presented here constitute a database of the micro-droplets produced to validate models of droplet impact outcomes.

Modeling residential exposure to secondhand tobacco smoke

We apply a simulation model to explore the effect of a house's multicompartment character on a nonsmoker's inhalation exposure to secondhand tobacco smoke (SHS). The model tracks the minute-by-minute movement of people and pollutants among multiple zones of a residence and generates SHS pollutant profiles for each room in response to room-specific smoking patterns. In applying the model, we consider SHS emissions of airborne particles, nicotine, and carbon monoxide in two hypothetical houses, one with a typical four-room layout and one dominated by a single large space. We use scripted patterns of room-to-room occupant movement and a cohort of 5000 activity patterns sampled from a US nationwide survey. The results for scripted and cohort simulation trials indicate that the multicompartment nature of homes, manifested as inter-room differences in pollutant levels and the movement of people among zones, can cause substantial variation in nonsmoker SHS exposure.

Carcinogenicity of inhaled vanadium pentoxide in F344/N rats and B6C3F1 mice.

Vanadium pentoxide (V2O5) is a slightly soluble compound found in airborne particle emissions from metallurgical works and oil and coal burning. Because the carcinogenic potential of V2O5 was not known, F344/N rats and B6C3F1 mice (N=50/sex/species) were exposed to V2O5 at concentrations of 0, 0.5 (rats only), 1, 2, or 4 (mice only) mg/m3, by whole-body inhalation for 2 years. The survival and body weights of rats were minimally affected by exposure to V2O5. The survival and body weights of male mice exposed to 4 mg/m3 and body weights of all exposed groups of female mice were lower than the controls. Alveolar/bronchiolar (A/B) neoplasms occurred in male rats exposed to 0.5 and 2 mg/m3 at incidences exceeding the National Toxicology Program (NTP) historical control ranges. A marginal increase in A/B neoplasms was also observed in female rats exposed to 0.5 mg/m3. Increases in chronic inflammation, interstitial fibrosis, and alveolar and bronchiolar hyperplasia/metaplasia and squamous metaplasia were observed in exposed male and female rats. A/B neoplasms were significantly increased in all groups of exposed mice. As with rats, increases in chronic inflammation, interstitial fibrosis, and alveolar and bronchiolar epithelial hyperplasia were observed in mice exposed to V2O5. Thus, V2O5 exposure was a pulmonary carcinogen in male rats and male and female mice. The marginal tumor response in the lungs of female rats could not be attributed conclusively to exposure to V2O5. These responses were noted at and slightly above the OSHA permissible occupational exposure limit of 0.5 mg/m3 (dust) (National Institute for Occupational Safety and Health, NIOSH Pocket Guide to Chemical Hazards, U.S. Department of Health and Human Services, Washington, DC, 1997, p. 328).

Characteristics of particle emissions at paint manufacturing

The handling of pigments and powders in paint manufacturing cause emissions of airborne particles. A great variety of substances occur. Previous studies (Bohgard et al., 1994) of simulations of pouring of pigments, which occur in small scale weighing procedures, showed typically bimodal size distribution including a sub-micron and a super-micron mode.The objective of the study was to get detailed knowledge on the relation between different source processes (depending on production technology, equipment and the manual handling routines) and aerosol characteristics.Super-micron particles were continuously measured with a time-of-flight instrument (Aerodynamic Particle Sizer, APS TSI Inc.) and sub-micron particles with an electric mobility spectrometer (Scanning Mobility Particle Sizer, SMPS TSI Inc.). In addition filter sampling techniques for standardised work-place sampling (so-called total dust filter cassettes, a cyclone sampler for respirable dust and IOM-samplers for inhalable dust) have been used for idealised exposure/area measurements using a rotating mannequin as a carrier of these samplers. The filters were analysed gravimetrically and with Particle Induced X-ray Emission Analysis. The aerosols were measured during manufacturing of batches of paint. Sources and source mechanisms, as pouring pigments from bags, disposal of packages, mixing of powders and pigments and suspected re-suspension sources, were documented simultaneously with the performance of the measurements.Figure 1 shows examples of size distributions obtained with the APS and SMPS. The size distributions have essentially bimodal shapes with median diameters of 0.05 -0.4 [mu ]m and of 2-5 [mu ]m respectively. Rapid variation in concentration occurs.Preliminary results show that several sources occur. Irregular activities and events as disposal of package material, cleaning, leakage from conveyor tubes and re-suspension due to wind velocities from open gates and moving vehicles significantly contribute to the particle concentrations.Filter sampling with the samplers mounted on a mannequin torso, rotating 360 degrees forth and back, is advantageous by giving idealised measures on exposure. Samplers mounted on equal horizontal level will have equal sampling location integrated over time. Furthermore, the sampling procedure emulate sampling in accordance with sampling conventions. Inlet characteristics of samplers mounted on a body differ from characteristics of free-hanging samplers (Vincent, 1989). Higher estimated mass concentrations were obtained with the IOM-samplers for inhalable dust than with the 37 mm open-face [ldquo ]total dust[rdquo ] cassettes.Figure omitted (Less)

回転４軸型クリーンロボットの開発

This paper describes design strategies and experimental results of the clean room robot which has airborne particle emission levels well within Class 1. Recently, there has been an increasing demand for clean room robots in the fields of semiconductor manufacturing, biotechnology, medical supplies, and so on. And a lot of SCARA type or Cartesian coordinates type clean room robots are developed for practical robots. These conventional robots perform a linear motion by a prismatic joint ; they have a defect in the structure for high degrees of cleanliness. Therefore, these robots utilize a linear-motion-cover such as a bellows and negative pressure by vacuum suction within the arm. To solve this problem, the proposed robot has a four axes pseudo-SCARA configuration with four revolute joints using a parallelogram arm mechanism ; cleanliness Class 1 is achieved by utilization magnetic fluid seals for all revolute joints without vacuum suction. Furthermore, a 32 bit high performance controller is used for reducing the effective current of the motors and a finite element method is used for reducing the moment of inertia while keeping the stiffness of the arm high. As a result, maximum speed 6 m/s and cycle time 0.98 second are achieved.

Pyrolysing insecticidal coils: Air pollution by polycyclic aromatic hydrocarbons and other mutagens detected by the Salmonella/microsome test

Pyrolysing insecticidal coils, which are used commonly for their evaporative release of insecticidal amounts of pyrethrins, have been investigated with respect to the emission of airborne particles, their mutagenic activity in the Salmonella/microsome mutagenicity test and their polycyclic aromatic hydrocarbons (PAH) content. Emitted particles contain compounds that are mutagenic in the absence of exogenous activation, as well as components that require mammalian activation. The particles also contain a range of PAH, but their concentration cannot account for the mutagenic response with mammalian activation. The use of pyrolysing insecticidal coils in semienclosed spaces may cause air pollution by releasing mutagenic and carcinogenic compounds that are of a magnitude similar to that found in other air pollution situations.

Emission of Airborne Particles and Bacteria from Human Body Wearing Cotton Surgical Gowns Related to the Frequency of Washing and Sterilizing Cycles

Emission of Airborne Particles and Bacteria from Human Body Wearing Cotton Surgical Gowns Related to the Frequency of Washing and Sterilizing Cycles

The determination of the optical properties of airborne particle emissions from diesel vehicles

The optical properties of diesel exhaust particulate emissions have been determined, using a number of techniques including photoacoustic spectroscopy and light extinction methods, in the laboratory and in an on-road setting. In the visible spectral region it is found that (1) light absorption accounts for most (∼ 3/4) of the light extinction and that (2) light absorption and total light extinction are caused primarily by elemental carbon. The mass-specific light absorption and light extinction coefficients can vary among vehicles by as much as a factor of 3 because of variation in the amount of the (transparent) organic component. The mass-specific absorption coefficient of the elemental carbon component is 9.8 ± 1.5 m 2/g at λ = 0.50 nm.

Strategies for the Optimal Control of Dust Emissions from Unpaved Roads

Travel on unpaved public roads is the single largest anthropogenic source of emissions of airborne particles in the U.S. The average impact of this source on average annual mean total suspended particulate (TSP) concentrations varies from 0.05 μg/m3 (Alaska) to 11 μg/m3 (Pennsylvania). When compared by contributions to the variance in state to state TSP levels, their impact is as great as the impact of emissions from all conventional sources. Common emission control methods include paving, oiling, speed reduction, watering, and application of calcium chloride. Total annual emissions are, in most cases, most economically reduced by either speed control or paving, with expected average control costs of less than $0.50/lb of emissions reductions. For most roads with average daily traffic flows above 100 vehicles per day, paving is shown to control emissions at average costs of less than $0.05/lb. In some situations, the costs of paving are more than offset by reductions in maintenance costs. Thus it would appear that, even accounting for the order of magnitude lower impact on statewide average concentration per ton of particles emitted from open sources, control of dust emissions from unpaved roads offers an economical means for reducing ambient TSP levels.