Nanoparticle emissions from biofuelled vehiclestheir characteristics and impact on the number‐based regulation of atmospheric particles (original) (raw)
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Nanoparticle emissions from 11 non-vehicle exhaust sources – A review
Atmospheric Environment, 2013
Nanoparticle emissions from road vehicles have been studied extensively in the recent past due to their dominant contribution towards the total airborne particle number concentrations (PNCs) found in the urban atmospheric environment. In view of upcoming tighter vehicle emission standards and adoption of cleaner fuels in many parts of the world, the contribution to urban nanoparticles from non-vehicle exhaust sources (NES) may become more pronounced in future. As of now, only limited information exists on nanoparticle emissions from NES through the discretely published studies. This article presents critically synthesised information in a consolidated manner on 11 NES (i.e. roadtyre interaction, construction and demolition, aircraft, ships, municipal waste incineration, power plants, domestic biomass burning, forest fires, cigarette smoking, cooking, and secondary formation). Source characteristics and formation mechanisms of nanoparticles emitted from each NES are firstly discussed, followed by their emission strengths, airborne concentrations and physicochemical characteristics. Direct comparisons of the strengths of NES are not straightforward but an attempt has been made to discuss their importance relative to the most prominent source (i.e. road vehicles) of urban nanoparticles. Some interesting comparisons emerged such as 1 kg of fast and slow wood burning produces nearly the same number of particles as for each km driven by a heavy duty vehicle (HDV) and a light duty vehicle, respectively. About 1 minutes of cooking on gas can produce the similar particle numbers generated by ~10 minutes of cigarette smoking or 1 m travel by a HDV. Apportioning the contribution of numerous sources from the bulk measured airborne PNCs is essential for determining their relative importance. Receptor modelling methods for estimation of source emission contributions are discussed. A further section evaluates the likely exposure risks, health and regulatory implications associated with each NES. It is concluded that much research is needed to provide adequate quantification of all nanoparticle sources, and to establish the relative toxicity of nanosize particles from each.
Energy & Fuels, 2009
Nanosized particles emitted from automotive engines continue to attract concern because of their adverse health effects and their impact on the environment. Automotive engines are a major source of fine and ultrafine particles emitted into the atmosphere. Through stricter emission regulations and the introduction of advanced technologies, the specific particulate mass emissions (in g/km and g/kWh) from internal combustion engines have decreased by about 1 order of magnitude since the 1980s. However, the number concentration of nanoparticles (No./m 3) emitted from internal combustion engines may continue to increase considerably and has recently attracted the attention of the Particle Measurement Programme (PMP). This program is intended to evaluate engine nanoparticle measurement systems for use in future emission regulations. In the study reported in this paper, two latest-generation engines, one spark-ignited and the other compression-ignited, were used for a comparison of the particulate emission characteristics, including number density. Both engines were single-cylinder with the same displacement volume of 500 cm 3 , and neither included after-treatment traps or catalytic converters. Test fuels used for the study were: gasoline and E85 (mixture of 85% ethanol and 15% gasoline, sometimes called gasohol) for the spark-ignited engine having a compression ratio of 10; and ultralow sulfur diesel (ULSD) and BD100 (100% biodiesel, i.e. soybean methyl ester) for the compression-ignited engine having a compression ratio of 15. A fast-response particle spectrometer (DMS500) with heated sample line was used for continuous measurement of the particle size and number distribution in the size range of 5-1000 nm (aerodynamic diameter). The experimental results showed that particle number peaked within the range of 10-300 nm under all engine operating conditions, regardless of engine combustion type. An observed shift toward larger particle size with increasing engine load could be explained by particle coagulation. The effect of the different fuels on nanoparticle size distributions was dependent on the engine type (spark-ignition or compression-ignition).
Contribution of traffic-originated nanoparticle emissions to regional and local aerosol levels
2021
Sub-50 nm particles originating from traffic emissions pose risks to human health due to their high lung deposition efficiency and potentially harmful chemical composition. We present a modeling study using an updated European Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) number emission inventory, incorporating a more realistic, empirically justified particle size distribution (PSD) for sub-50 nm particles from road traffic as compared with the previous version. We present experimental PSDs and CO 2 concentrations, measured in a highly trafficked street canyon in Helsinki, Finland, as an emission factor particle size distribution (EFPSD), which was then used in updating the EUCAARI inventory. We applied the updated inventory in a simulation using the regional chemical transport model PMCAMx-UF over Europe for May 2008. This was done to test the effect of updated emissions at regional and local scales, particularly in comparison with atmospheric new particle formation (NPF). Updating the inventory increased the simulated average total particle number concentrations by only 1 %, although the total particle number emissions were increased to a 3-fold level. The concentrations increased up to 11 % when only 1.3-3 nm sized particles (nanocluster aerosol, NCA) were considered. These values indicate that the effect of updating overall is insignificant at a regional scale during this photochemically active period. During this period, the fraction of the total particle number originating from atmospheric NPF processes was 91 %; thus, these simulations give a lower limit for the contribution of traffic to the aerosol levels. Nevertheless, the situation is different when examining the effect of the update closer spatially or temporally or when focusing on the chemical composition or the origin of the particles. For example, the daily average NCA concentrations increased by a factor of several hundred or thousand in some locations on certain days. Overall, the most significant effects-reaching several orders of magnitude-from updating the inventory are observed when examining specific particle sizes (especially 7-20 nm), particle components, and specific urban areas. While the model still has a tendency to predict more sub-50 nm particles compared to the observations, the most notable underestimations in the concentrations of sub-10 nm particles are now overcome. Additionally, the simulated distributions now agree better with the data observed at locations with high traffic densities. The findings of this study highlight the need to consider emissions, PSDs, and composition of sub-50 nm particles from road traffic in studies focusing on urban air quality. Updating this emission source brings the simulated aerosol levels, particularly in urban locations, closer to observations, which highlights its importance for calculations of human exposure to nanoparticles.
Nanoparticle emissions from gasoline vehicles DI MPI
Combustion Engines
The nanoparticles (NP) count concentrations are limited in EU for all Diesel passenger cars since 2013 and for gasoline cars with direct injection (GDI) since 2014. For the particle number (PN) of MPI gasoline cars there are still no legal limitations. In the present paper some results of investigations of nanoparticles from five DI and four MPI gasoline cars are represented. The measurements were performed at vehicle tailpipe and in CVS-tunnel. Moreover, five variants of “vehicle – GPF” were investigated. The PN-emission level of the investigated GDI cars in WLTC without GPF is in the same range of magnitude very near to the actual limit value of 6.0 × 10^12 1/km. With the GPF’s with better filtration quality, it is possible to lower the emissions below the future limit value of 6.0 × 10^11 1/km. The modern MPI vehicles also emit a considerable amount of PN, which in some cases can attain the level of Diesel exhaust gas without DPF and can pass over the actual limit value for GDI (...
Rapid urbanisation in developing megacities like Delhi has resulted in an increased number of road vehicles and hence total particle number (ToN) emissions. For the first time, this study presents preliminary estimates of ToN emissions from road vehicles, roadside and ambient ToN concentrations, and exposure related excess deaths in Delhi in current and two future scenarios; business as usual (BAU) and best estimate scenario (BES). Annual ToN emissions are estimated as 1.37 Â 10 25 for 2010 which are expected to increase by ∼4 times in 2030-BAU, but to decrease by ∼18 times in 2030-BES. Such reduction is anticipated due to a larger number of compressed natural gas driven vehicles and assumed retrofitting of diesel particulate filters to all diesel vehicles by 2020. Heavy duty vehicles emit the majority (∼65%) of ToN for only ∼4% of total vehicle kilometres traveled in 2010. Their contribution remains dominant under both scenarios in 2030, clearly requiring major mitigation efforts. Roadside and ambient ToN concentrations were up to a factor of 30 and 3 higher to those found in respective European environments. Exposure to ambient ToN concentrations resulted in ∼508, 1888, and 31 deaths per million people in 2010, 2030-BAU and 2030-BES, respectively.
Technical challenges in tackling regulatory concerns for urban atmospheric nanoparticles
2011
Recent Euro-5 and Euro-6 vehicle emission standards are the first ever initiative to control particles on a number basis at the source. Related standards are also desirable for ambient nanoparticles (taken in this article to be those below 300 nm) to protect against possible adverse impacts on public health and the environment. However, there are a number of technical challenges that need to be tackled before developing a regulatory framework for atmospheric nanoparticles. Some of the challenges derive from a lack of standardisation of the key measurement parameters, including sampling, necessary for robust evaluation of particle number concentrations, especially in the context of insufficient knowledge of the physicochemical characteristics of emerging sources (i.e. bio-fuel derived and manufactured nanoparticles). Ideally, ambient concentrations of primary particles could be linked to primary particle emissions by use of nanoparticle dispersion models, and secondary nanoparticles using photochemical modelling tools. The limitations in these areas are discussed. Although there is inadequate information on the exact biological mechanism through which these particles cause harm, it is argued that this should not in itself delay the introduction of regulation. This article reviews the missing links between the existing knowledge of nanoparticle number concentrations and the advances required to tackle the technical challenges implied in developing regulations.
Influence of Diesel Fuel Sulfur on Nanoparticle Emissions from City Buses
Environmental Science & Technology, 2006
Particle emissions from twelve buses, operating alternately on low sulfur (LS; 500 ppm) and ultralow sulfur (ULS; 50 ppm) diesel fuel, were monitored. The buses were 1-19 years old and had no after-treatment devices fitted. Measurements were carried out at four steady-state operational modes on a chassis dynamometer using a mini dilution tunnel (PM mass measurement) and a Dekati ejector diluter as a secondary diluter (SMPS particle number). The mean particle number emission rate (s -1 ) of the buses, in the size range 8-400 nm, using ULS diesel was 31% to 59% lower than the rate using LS diesel in all four modes. The fractional reduction was highest in the newest buses and decreased with mileage up to about 500 000 km, after which no further decrease was apparent. However, the mean total suspended particle (TSP) mass emission rate did not show a systematic difference between the two fuel types. When the fuel was changed from LS to ULS diesel, the reduction in particle number was mainly in the nanoparticle size range. Over all operational modes, 58% of the particles were smaller than 50 nm with LS fuel as opposed to just 45% with ULS fuel, suggesting that sulfur in diesel fuel was playing a major role in the formation of nanoparticles. The greatest influence of the fuel sulfur content was observed at the highest engine load, where 74% of the particles were smaller than 50 nm with LS diesel compared to 43% with ULS diesel.
Atmospheric Environment, 2010
The likely health and environmental implications associated with atmospheric 9 nanoparticles have prompted considerable recent research activity. Knowledge of the 10 characteristics of these particles has improved considerably due to an ever growing interest in 11 the scientific community, though not yet sufficient to enable regulatory decision making on a 12 particle number basis. This review synthesizes the existing knowledge of nanoparticles in the 13 urban atmosphere, highlights recent advances in our understanding and discusses research 14 priorities and emerging aspects of the subject. The article begins by describing the 15 characteristics of the particles and in doing so treats their formation, chemical composition 16 and number concentrations, as well as the role of removal mechanisms of various kinds. This 17 is followed by an overview of emerging classes of nanoparticles (i.e. manufactured and bio-18 fuel derived), together with a brief discussion of other sources. The subsequent section 19 provides a comprehensive review of the working principles, capabilities and limitations of the 20 main classes of advanced instrumentation that are currently deployed to measure number and 21 size distributions of nanoparticles in the atmosphere. A further section focuses on the 22 dispersion modelling of nanoparticles and associated challenges. Recent toxicological and 23 epidemiological studies are reviewed so as to highlight both current trends and the research 24 needs relating to exposure to particles and the associated health implications. The review then 25 addresses regulatory concerns by providing an historical perspective of recent developments 26 together with the associated challenges involved in the control of airborne nanoparticle 27
Sources and concentration of nanoparticles (< 10 nm diameter) in the urban atmosphere
Atmospheric Environment, 2001
Whilst limited information on particle size distributions and number concentrations in cities is available, very few data on the very smallest of particles, nanoparticles, have been recorded. Measurements in this study show that road tra$c and stationary combustion sources generate a signi"cant number of nanoparticles of diameter (10 nm. Measurements at the roadside (4 m from the kerb) and downwind from the tra$c (more than 25 m from the kerb) show that nanoparticles ( (10 nm diameter) accounted for more than 36}44% of the total particle number concentrations. Measurements designed to sample the plume of individual vehicles showed that both a diesel-and a petrol-fuelled vehicle generated nanoparticles ( (10 nm diameter). The fraction of nanoparticles was even greater in a plume 350 m downwind of a stationary combustion source. On a few occasions, a temporal association between nanoparticles in the size range 3}7 nm and solar radiation was observed in urban background air at times when no other local sources were in#uential, which suggests that homogeneous nucleation can also be an important source of particles in the urban atmosphere.