Wohlen, Switzerland
Wohlen, Switzerland

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Pelzer J.,Institute For Arbeitsschutz Der Deutschen Gesetzlichen Unfallversicherung Ifa | Bischof O.,TSI GmbH | Van Den Brink W.,Philips | Fierz M.,Fachhochschule Nordwestschweiz | And 6 more authors.
Gefahrstoffe Reinhaltung der Luft | Year: 2010

In order for the growing significance of nanotechnology to be addressed by occupational safety and health as well as from other aspects, workplace exposure to nanoparticles must be determined and examined. The quantity of measurement most frequently employed for nanoparticles is the particle number concentration. Seven contributions by six manufacturers provide an introduction to the subject of measurement. The manufacturers provide a presentation of their equipment for this measurement task. The particle size range covered by the instruments should extend from approximately 10 to 300 nm, in order to cover both discrete nanoparticles and their agglomerates. The instruments can be divided into two groups: larger, static instruments that deliver measurement results broken down by particle size, and smaller instruments that are transportable or worn on the person and which deliver a total concentration.


Muller L.,University of Bern | Muller L.,Bern University of Applied Sciences | Comte P.,Bern University of Applied Sciences | Czerwinski J.,Bern University of Applied Sciences | And 10 more authors.
Toxicological and Environmental Chemistry | Year: 2012

The aim of this study was to compare the cytotoxicity and the (pro-)inflammatory responses of two-stroke (direct injection and carburetor technology) and four-stroke scooter and diesel car exhaust emissions on lung cells in vitro. This was analyzed by exposing a 3D in vitro model of the epithelial airway (consisting of human bronchial epithelial cells (cell line 16HBE14o-) combined with human whole blood monocyte-derived macrophages and dendritic cells) to physically characterized exhaust emissions. Biological endpoints of cytotoxicity (lactate dehydrogenase release), as well as pro-inflammatory cytokine (tumor necrosis factor (TNF)-α) and inflammatory chemokine (interleukin(IL)-8) stimulation were examined. Two-stroke direct injection scooter exhaust contained the highest particle number concentration and nitrogen oxides (NOx) concentrations and the emissions from the two-stroke carburetor scooter contained the highest hydrocarbon and lowest NOx concentrations. The four-stroke scooter emitted the highest carbon monoxide concentration whereas the cars emitted the lowest. The combination of various technical optimizations for the two-stroke direct injection scooter (particle filter, oxidative catalyst, better oil and fuel) reduced the total emissions strongly and the TNF-α concentration significantly (p < 0.05). The cytotoxicity and the IL-8 concentration showed strong tendencies to be reduced. The analysis of the emissions of all tested two-stroke, four-stroke scooters and diesel cars showed a strong association between the adverse effects and the particle number concentration. © 2011 Taylor and Francis Group, LLC.


Heeb N.V.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Haag R.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Seiler C.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Schmid P.,Empa - Swiss Federal Laboratories for Materials Science and Technology | And 10 more authors.
Environmental Science and Technology | Year: 2012

The impact of a combined diesel particle filter-deNOx system (DPN) on emissions of reactive nitrogen compounds (RNCs) was studied varying the urea feed factor (α), temperature, and residence time, which are key parameters of the deNOx process. The DPN consisted of a platinum-coated cordierite filter and a vanadia-based deNOx catalyst supporting selective catalytic reduction (SCR) chemistry. Ammonia (NH 3) is produced in situ from thermolysis of urea and hydrolysis of isocyanic acid (HNCO). HNCO and NH3 are both toxic and highly reactive intermediates. The deNOx system was only part-time active in the ISO8178/4 C1cycle. Urea injection was stopped and restarted twice. Mean NO and NO2 conversion efficiencies were 80%, 95%, 97% and 43%, 87%, 99%, respectively, for α = 0.8, 1.0, and 1.2. HNCO emissions increased from 0.028 g/h engine-out to 0.18, 0.25, and 0.26 g/h at α = 0.8, 1.0, and 1.2, whereas NH3 emissions increased from <0.045 to 0.12, 1.82, and 12.8 g/h with maxima at highest temperatures and shortest residence times. Most HNCO is released at intermediate residence times (0.2-0.3 s) and temperatures (300-400 C). Total RNC efficiencies are highest at α = 1.0, when comparable amounts of reduced and oxidized compounds are released. The DPN represents the most advanced system studied so far under the VERT protocol achieving high conversion efficiencies for particles, NO, NO2, CO, and hydrocarbons. However, we observed a trade-off between deNOx efficiency and secondary emissions. Therefore, it is important to adopt such DPN technology to specific application conditions to take advantage of reduced NOx and particle emissions while avoiding NH3 and HNCO slip. © 2012 American Chemical Society.


Heeb N.V.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Zennegg M.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Haag R.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Wichser A.,Empa - Swiss Federal Laboratories for Materials Science and Technology | And 11 more authors.
Environmental Science and Technology | Year: 2013

Catalytic diesel particle filters (DPFs) have evolved to a powerful environmental technology. Several metal-based, fuel soluble catalysts, so-called fuel-borne catalysts (FBCs), were developed to catalyze soot combustion and support filter regeneration. Mainly iron-and cerium-based FBCs have been commercialized for passenger cars and heavy-duty vehicle applications. We investigated a new iron/potassium-based FBC used in combination with an uncoated silicon carbide filter and report effects on emissions of polychlorinated dibenzodioxins/furans (PCDD/Fs). The PCDD/F formation potential was assessed under best and worst case conditions, as required for filter approval under the VERT protocol. TEQ-weighted PCDD/F emissions remained low when using the Fe/K catalyst (37/7.5 μg/g) with the filter and commercial, low-sulfur fuel. The addition of chlorine (10 μg/g) immediately led to an intense PCDD/F formation in the Fe/K-DPF. TEQ-based emissions increased 51-fold from engine-out levels of 95 to 4800 pg I-TEQ/L after the DPF. Emissions of 2,3,7,8-TCDD, the most toxic congener (TEF = 1.0), increased 320-fold, those of 2,3,7,8-TCDF (TEF = 0.1) even 540-fold. Remarkable pattern changes were noticed, indicating a preferential formation of tetrachlorinated dibenzofurans. It has been shown that potassium acts as a structural promoter inducing the formation of magnetite (Fe3O4) rather than hematite (Fe2O 3). This may alter the catalytic properties of iron. But the chemical nature of this new catalyst is yet unknown, and we are far from an established mechanism for this new pathway to PCDD/Fs. In conclusion, the iron/potassium-catalyzed DPF has a high PCDD/F formation potential, similar to the ones of copper-catalyzed filters, the latter are prohibited by Swiss legislation. © 2013 American Chemical Society.


Heeb N.V.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Zimmerli Y.,University of Applied Sciences and Arts Western Switzerland | Czerwinski J.,University of Applied Sciences and Arts Western Switzerland | Schmid P.,Empa - Swiss Federal Laboratories for Materials Science and Technology | And 11 more authors.
Atmospheric Environment | Year: 2011

Long-term exposure to increased levels of reactive nitrogen compounds (RNCs) and particulate matter (PM) affect human health. Many cities are currently not able to fulfill European air quality standards for these critical pollutants. Meanwhile, promising new abatement technologies such as diesel particle filters (DPFs) and selective catalytic reduction (SCR) catalysts are developed to reduce PM and RNC emissions. Herein, effects of a urea-based SCR system on RNC emissions are discussed and we quantified the highly reactive intermediates isocyanic acid (HNCO) and ammonia (NH3), both potential secondary pollutants of the urea-based SCR chemistry. A diesel engine (3.0 L, 100 kW), operated in the ISO 8178/4 C1, cycle was used as test platform. A V2O5-based SCR catalyst was either applied as such or down-stream of a high oxidation potential-DPF (hox-DPF). With active SCR, nitric oxide (NO) and nitrogen dioxide (NO2) conversion efficiencies of 0.86-0.94 and 0.86-0.99 were obtained. On the other hand, mean HNCO and NH3 emissions increased to 240-280 and 1800-1900 mg h-1. On a molar basis, HNCO accounted for 0.8-1.4% and NH3 for 14-25% of the emitted RNCs. On roads, SCR systems will partly be inactive when exhaust temperatures drop below 220 °C. The system was active only during 75% of the test cycle, and urea dosing was stopped and restarted several times. Consequently, NO conversion stopped but interestingly, NO2 was still converted. Such light-off and shutdown events are frequent in urban driving, compromising the overall deNOx efficiency. Another important effect of the SCR technology is illustrated by the NH3/NO2 ratio, which was >1 with active SCR, indicating that exhaust is basic rather than acidic after the SCR catalyst. Under these conditions, isocyanic acid is stable. The widespread use of various converter technologies already affected RNC release. Diesel oxidation catalysts (DOCs) and hox-DPFs increased NO2 emissions, three-way catalysts (TWCs) those of NH3. The investigated SCR technology substantially lowered NO and NO2 emissions, while NH3 levels were comparable to those of TWC vehicles (300-1500 mg h-1). If applied in the future, the combined DPF/SCR technology will change ambient RNC levels, PM compositions and atmospheric redox- and acid/base-chemistry in traffic-affected areas. © 2011 Elsevier Ltd.


Tartakovsky L.,Technion - Israel Institute of Technology | Baibikov V.,Technion - Israel Institute of Technology | Czerwinski J.,University of Applied Sciences and Arts Western Switzerland | Gutman M.,Technion - Israel Institute of Technology | And 4 more authors.
Atmospheric Environment | Year: 2013

This work presents results of particle mass, number and size measurements inside passenger cars (PCs), vans and urban buses. Effects of the in-cabin air purifier on particle concentrations and average size inside a vehicle are studied. Use of the air purifier leads to a dramatic reduction, by 95-99%, in the measured ultrafine particles number concentration inside a vehicle compared with outside readings. Extremely low particle concentrations may be reached without a danger of vehicle occupants' exposure to elevated CO2 levels. The lowest values of particle concentrations inside a PC without air purifier are registered under the recirculation ventilation mode, but the issue of CO2 accumulation limits the use of this mode to very short driving events. Lower PM concentrations are found inside newer cars, if this ventilation mode is used. Great differences by a factor of 2.5-3 in PM10 concentrations are found between the PCs and the buses. Smoking inside a car leads to a dramatic increase, by approximately 90 times, in PM2.5 concentrations. © 2012 Elsevier Ltd.

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