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In this paper, we reconstruct the vertical profile of volcanic ash emissions by assimilating satellite data and ground‐based observations using a modified trajectory‐based 4D‐Var (Trj4DVar) approach. In our previous work, we found that the lack of vertical resolution in satellite ash column data can result in a poor estimation of the injection layer where the ash is emitted into the atmosphere. The injection layer is crucial for the forecast of volcanic ash clouds. To improve estimation, Trj4DVar was implemented, and it has shown increased performance in twin experiments using synthetic observations. However, there are some cases with real satellite data where Trj4DVar has difficulty in obtaining an accurate estimation of the injection layer. To remedy this, we propose a modification of Trj4DVar, test it with synthetic twin experiments, and evaluate real data performance. The results show that the modified Trj4DVar is able to accurately estimate the injection height (location of the maximal emission rate) by incorporating the plume height (top of the ash plume) and mass eruption rate data obtained from ground‐based observations near the source into the assimilation system. This will produce more accurate emission estimations and more reliable forecasts of volcanic ash clouds. Also provided are two strategies on the preprocessing and proper use of satellite data.

Mapping of road traffic noise in urban areas according to standardized engineering calculation methods systematically results in an underestimation of noise levels at areas shielded from direct exposure to noise, such as inner yards. In most engineering methods, road traffic lanes are represented by point sources and noise levels are computed utilizing point-to-point propagation paths. For a better prediction of noise levels in shielded urban areas, an extension of engineering methods by an attenuation term Acan has been proposed, including multiple reflections of the urban environment both in the source and in the receiver area. The present work has two main contributions for the ease of computing Acan. Firstly, it is shown by numerical calculations that Acan may be divided into independent source and receiver environment terms, As and Ar. Based on an equivalent free field analogy, the distance dependence of these terms may moreover be expressed analytically. Secondly, an analytical expression is proposed to compute As and Ar for 3D configurations from using 2D configurations only. The expression includes dependence of the street width-to-height ratio, the difference in building heights and the percentage of facade openings in the horizontal plane. For the expression to be valid, the source should be separated from the receiver environment by at least four times the street width. © S. Hirzel Verlag EAA.

Background: Synthetic Amorphous Silica (SAS) is commonly used in food and drugs. Recently, a consumer intake of silica from food was estimated at 9.4 mg/kg bw/day, of which 1.8 mg/kg bw/day was estimated to be in the nano-size range. Food products containing SAS have been shown to contain silica in the nanometer size range (i.e. 5 - 200 nm) up to 43% of the total silica content. Concerns have been raised about the possible adverse effects of chronic exposure to nanostructured silica.Methods: Rats were orally exposed to 100, 1000 or 2500 mg/kg bw/day of SAS, or to 100, 500 or 1000 mg/kg bw/day of NM-202 (a representative nanostructured silica for OECD testing) for 28 days, or to the highest dose of SAS or NM-202 for 84 days.Results: SAS and NM-202 were extensively characterized as pristine materials, but also in the feed matrix and gut content of the animals, and after in vitro digestion. The latter indicated that the intestinal content of the mid/high-dose groups had stronger gel-like properties than the low-dose groups, implying low gelation and high bioaccessibility of silica in the human intestine at realistic consumer exposure levels. Exposure to SAS or NM-202 did not result in clearly elevated tissue silica levels after 28-days of exposure. However, after 84-days of exposure to SAS, but not to NM-202, silica accumulated in the spleen. Biochemical and immunological markers in blood and isolated cells did not indicate toxicity, but histopathological analysis, showed an increased incidence of liver fibrosis after 84-days of exposure, which only reached significance in the NM-202 treated animals. This observation was accompanied by a moderate, but significant increase in the expression of fibrosis-related genes in liver samples. Conclusions: although only few adverse effects were observed, additional studies are warranted to further evaluate the biological relevance of observed fibrosis in liver and possible accumulation of silica in the spleen in the NM-202 and SAS exposed animals respectively. In these studies, dose-effect relations should be studied at lower dosages, more representative of the current exposure of consumers, since only the highest dosages were used for the present 84-day exposure study. © 2014 van der Zande et al.; licensee BioMed Central Ltd.

The capacity of Particulate Matter (PM) to oxidise target molecules, defined as its oxidative potential (OP), has been proposed as a biologically more relevant metric than PM mass. Different assays exist for measuring OP and their methodologies vary in the choice of extraction solvent and filter type. Little is known about the impact of extraction and filter type on reported OP. Four a-cellular assays; electron spin resonance (ESR), dithiothreitol (DTT), ascorbate acid depletion (AA) and reductive acridinium triggering (CRAT) assay were chosen to evaluate whether these differences affect the OP measurement, the correlation between OP from different assays and the association with PM chemical composition. We analysed 15 urban 48-72h PM2.5 samples collected on quartz and Teflon filters. The choice of extraction solvent had only a significant effect on OPDTT, while all OP measures for quartz filters were heavily attenuated. OP values derived from quartz were, however, highly correlated with those derived from Teflon. OPDTT correlated highly with OPCRAT, and OPESR correlated highly with OPAA. These correlations were affected by the choice of filter type. Correlations between OP and PM chemical composition were not affected by filter type and extraction solvent. These findings indicate that the measurement of relative OP reactivity is not greatly influenced by filter type and extraction solvent for the investigated assays. This robustness is also promising for exploratory use in monitoring and subsequent epidemiological studies. © 2013 The Authors.

Pollution levels in urban areas and their surrounding rural regions differ due to different sources and density of emissions, different composition of pollutants as well as specific meteorological effects. These concentration differences for PM10 are investigated and compared in this study for three different north-west European urban agglomerations: The German Ruhr area, the Dutch Randstad and the German city of Berlin. Measurement data for PM10 for the years 2003-2008 at urban and rural background stations are selected from the AirBase database to specify the PM10 concentration difference between these urban areas and their surrounding rural regions, here defined as the urban increment. Whereas the absolute and relative measured urban increment averaged over the years 2003-2008 for the Ruhr area (7.4μgm-3, 35%) and Berlin (8.5μgm-3, 46%) are comparable in magnitude, a significantly smaller value is found for the Randstad (3.1μgm-3, 12%). To analyze whether the regional chemistry transport model LOTOS-EUROS is able to reproduce the measured urban increment simulation runs were performed for 2003-2008 on a 0.5°×0.25° lon-lat grid covering Europe and for the year 2008 on a finer grid of 0.125°×0.0625° covering the Netherlands and Germany, both with ECMWF meteorology as input. Although the model underestimates the absolute PM10 urban increment averaged over the years 2003-2008 for the Ruhr area (3.3μgm-3, 33%), the Randstad (1.5μgm-3, 12%) and Berlin (1.7μgm-3, 27%), the relative urban increment for the Ruhr area and the Randstad is in general agreement with the measurements. The tested increase of the horizontal resolution gives no systematic improvement of the simulated urban increment. However, an even higher resolution than used here seems to be more appropriate to capture the urban increment (especially for Berlin).The variability of the PM10 urban increment with weather is tested by means of the summer 2003, such an extreme synoptic situation is expected to occur more often in future. Measured and simulated PM10 concentrations in summer 2003 were compared to the summer average of 2003-2008. The response of the observed urban increment was found to depend on the urban area. In general the model reproduces the main features for the Randstad and Berlin.In order to investigate the impact of a changing climate on the PM10 urban increment, simulations were performed with the off-line coupled model system RACMO2 (regional climate model) - LOTOS-EUROS (air quality model) over Europe. Different sets of simulations were carried out using RACMO2 meteorology with ECHAM5 A1B and with MIROC3.2-hires A1B boundary conditions for the time period 1970-2060, as well as with ERA-interim boundary conditions for the time period 1989-2009. Anthropogenic emissions were kept constant in the LOTOS-EUROS simulations. Simulated concentrations differ between the runs using ECHAM and MIROC boundary conditions and both runs differ from the present-day simulations with ERA-interim forcing. The impact of climate change on the modeled PM10 concentrations and the urban increment was found to be small in both scenario runs. However the concentration differences between the simulations forced by either ECHAM or MIROC indicate that PM10 concentration levels are sensitive to circulation patterns rather than temperature change alone, and that PM10 concentration levels may thus change when circulation patterns change in the future. © 2013 Elsevier Ltd.

An overview of regional-scale quality modeling practices and perspectives in North America and Europe, highlighting the differences and commonalities in how regional-scale air quality modeling systems are being used and evaluated across both continents

Buiten vastgestelde kaders denken draagt wezenlijk bij aan het verbeteren van onze veiligheid. In Nederland is dit echter uitermate moeilijk. Eerste stap om de huidige praktijk te verbeteren vormt het standaard inschakelen van het RIVM

Several types of diesel exhaust particles (DEPs) have been used for toxicology studies, including a highorganic automobile DEP (A-DEP) from Japan, and a low-organic forklift DEP developed by the National Institute of Standards and Technology (N-DEP). However, these DEPs were not characterized extensively for chemical composition or sub-fractionated and tested extensively for mutagenicity. We collected a compressor-generated DEP (C-DEP) and characterized it by conducting bioassay-directed fractionation of the extractable organics in Salmonella and correlating the results by hierarchical clustering with the concentrations of 32 polycyclic aromatic hydrocarbons (PAHs). Relative to A- and N-DEP, the mutagenic potency of C-DEP was intermediate in TA100 1S9 (PAH mutagenicity) but was lowest in TA98 – S9 (nitroarene mutagenicity). More than 50% of the mass of the extractable organics of C-DEP eluted in the nonpolar fraction 1, and only -20% eluted in the moderately polar Fractions 2 and 3. However, most of the mutagenicity eluted in Fractions 2 and 3, similar to A-DEP but different from N-DEP. HPLC-derived mutagrams of 62 sub-fractions per fraction confirmed that most of the mutagenicity was due to moderately polar compounds. The diagnostic strains identified a strong role for PAHs, nitroarenes, aromatic amines, and oxy-PAHs in the mutagenicity of C-DEP. Hierarchical clustering confirmed the importance of oxy-PAHs but not that of nitroarenes. To our knowledge this is the first use of hierarchical clustering to correlate chemical composition with the mutagenicity of a complex mixture. The chemical analysis and mutagenicity of C-DEP described here makes C-DEP suitable for additional toxicological studies.

The advent of satellite data has provided a source of independent information to monitor trends in tropospheric nitrogen dioxide levels. To interpret these trends, one needs to know the sensitivity of the satellite retrieved NO2 column to anthropogenic emissions. We have applied a chemistry transport model to investigate the sensitivity of the modeled NO2 column, sampled at the OMI (Ozone Monitoring Instrument) overpass time and location and weighted by the OMI averaging kernel, to emission sources across Europe. The most important contribution (~35%) in Western Europe is made by road transport. Off-road transport and industrial combustion each contribute 10%-15% across continental Europe. In Eastern Europe, power plant contributions are of comparable magnitude as those of road transport. To answer the question if the OMI-NO2 trends can be translated directly into emission changes, we assessed the anticipated changes in OMI-NO2 between 2005 and 2020. Although the results indicated that for many countries, it is indeed possible, for medium- and small-sized coastal countries, the contribution of the increasing shipping emissions in adjacent sea areas may mask a significant part of national emission reductions. This study highlights the need for a combined use of models, a priori emission estimates and satellite data to verify emission trends. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Het Nederlandse externe veiligheidsbeleid in relatie tot gevaarlijke stoffen is gebaseerd op de resultaten van de kwantitatieve risico analyse (QRA). Echter het standaard instrumentarium leent zich niet voor alle risico's van stationaire installaties zoals bleek btj het uitvoeren van de QRA voor Solvay Chemie in Herten nabij Roermond. De inrichting is aangewezen als BRZO-bedrijf vanwege het overschrrjden van de drempelwaarde voor oxiderende stoffen, genoemd in 'Besluit Risico Zware Ongevallen 1999' (4). Het gaat om de stof perazijnzuur. QRA berekeningen in Nederland moeten op geünificeerde wijze worden uitgevoerd volgens de Rekenmethodiek Bevi die bestaat uit de Handleiding Risicoberekeningen Bevi [3] en het rekenpakket Safeti-Nl. Bij een risicoanalyse worden zowel de effecten als de kansen van ongewenste voorvallen in beeld gebracht. In dit artikel wordt met name de effectenkant van de risicoanalyse belicht omdat juist de te berekenen effecten buiten de standaardkaders van de Handleiding Risicoberekening BEVI en Safeti-Nl, vallen. Zo voorzíet de geünificeerde werkwijze voor QRA berekeningen niet in het hanteren van mengsels (perazijnzuur en oleum), noch in het berekenen van niet-standaard scenario's zoals runaway reacties en ontleding van de gevaarlijke stof (perazijnzuur).

A multi-analytical approach to chemical analysis of inhalable urban atmospheric particulate matter (PM), integrating particle induced X-ray emission, inductively coupled plasma mass spectrometry/atomic emission spectroscopy, chromatography and thermal-optical transmission methods, allows comparison between hourly (Streaker) and 24-h (High volume sampler) data and consequently improved PM chemical characterization and source identification. In a traffic hot spot monitoring site in Madrid (Spain) the hourly data reveal metallic emissions (Zn, Cu, Cr, Fe) and resuspended mineral dust (Ca, Al, Si) to be closely associated with traffic flow. These pollutants build up during the day, emphasizing evening rush hour peaks, but decrease (especially their coarser fraction PM2.5-10) after nocturnal road washing. Positive matrix factorization (PMF) analysis of a large Streaker database additionally reveals two other mineral dust components (siliceous and sodic), marine aerosol, and minor, transient events which we attribute to biomass burning (K-rich) and industrial (incinerator?) Zn, Pb plumes. Chemical data on 24-h filters allows the measurement of secondary inorganic compounds and carbon concentrations and offers PMF analysis based on a limited number of samples but using fuller range of trace elements which, in the case of Madrid, identifies the continuing minor presence of a coal combustion source traced by As, Se, Ge and Organic Carbon. This coal component is more evident in the city air after the change to the winter heating season in November. Trace element data also allow use of discrimination diagrams such as V/Rb vs. La/Ce and ternary plots to illustrate variations in atmospheric chemistry (such as the effect of Ce-emissions from catalytic converters), with Madrid being an example of a city with little industrial pollution, recently reduced coal emissions, but serious atmospheric contamination by traffic emissions. © 2012 Elsevier Ltd.

High-speed stereo-PIV measurements were performed in the wake of 2.3 m wide fences (respectively 5 and 10 cm high). Average velocities and turbulent kinetic energy levels are given for a near fenceand a downstream field of view, showing the large recirculation zone of a near-2D obstacle. The results indicate that although PIV measurements can provide a good description of the turbulent flow around a wall-mounted fence, the lateral (perpendicular to the FOV) turbulence levels of the approach flow with roughness length of 0.3 mm are overestimated when compared to hot-wire measurements.

The impact of large cities on air pollution levels usually is determined with models driven by so-called downscaled emission inventories. This implies that annual emissions of air pollutants at the national scale are spatially distributed over a grid using proxy data like population density. These inventories are frequently used for regional air quality modeling but increasingly used also to assess air quality over cities. A key question is how much the assessment of city air pollution and exposure is influenced by downscaling of emission input data.Within this study we compare modeled nitrogen dioxide and particulate matter (PM) concentrations driven by a downscaled emission inventory with modeled concentrations driven by a 'bottom-up' emission inventory for the Paris region. Predicted concentrations and gradients in the concentrations are more consistent with observed concentrations when using the local bottom-up inventory. Both emissions and simulated concentrations of PM over urban sites in Paris are much lower due to different spatial distribution of the anthropogenic emissions. The difference for nearby rural stations is small implicating that the PM urban increment is much smaller than when using the downscaled emission inventory. Urban increments for PM based on conventional downscaled emissions may therefore be overestimated. © 2013 Elsevier Ltd.

Het werkterrein van TNO is aanzienlijk breder dan de tuinbouw alleen. Maar onderzoek in 'vreemde sectoren' levert geregeld inzichten op die ook bruikbaar zijn in de teelt van groenten, bloemen en planten. ln elke editie van GTT Magazine nemen wij een project van TNO onder de loep. Dit keer wél aandacht voor een 'echt tuinbouwproject', genaamd NoWaste.

Aerosol observations over the Arctic are important because of the effects of aerosols on Arctic climate, such as their direct and indirect effects on the Earth's radiation balance and on snow albedo. Although information on aerosol properties is available from ground-based measurements, passive remote sensing using satellite measurements would offer the advantage of large spatial coverage with good temporal resolution, even though, due to light limitations, this is only available during the Arctic summer. However, aerosol optical depth (AOD) retrieval over the Arctic region is a great challenge due to the high reflectance of snow and ice and due to the high solar zenith angle. In this article, we describe a retrieval algorithm using Advanced Along-Track Scanning Radiometer (AATSR) data, a radiometer flying on the European Space Agency (ESA) Environmental Satellite (ENVISAT), which offers two views (near nadir and at 55° forward) at seven wavelengths in the visible thermal-infrared (VIS-TIR). The main idea of the Dual-View Multi-Spectral (DVMS) approach is to use the dual view to separate contributions to reflectance measured at the top of the atmosphere (TOA) due to atmospheric aerosol and the underlying surface. The algorithm uses an analytical snow bidirectional reflectance distribution function (BRDF) model for the estimation of the ratio of snow reflectances in the nadir and forward views, as well as an estimate of the atmospheric contribution to TOA reflectance obtained using the dark pixel method over the adjacent ocean surface, assuming that this value applies over nearby land surfaces in the absence of significant sources across the coastline. An iteration involving all four AATSR wavebands in the visible near-infrared (VIS-NIR) is used to retrieve the relevant information. The method is illustrated for AATSR overpasses over Greenland with clear sky in April 2009. Comparison of the retrieved AOD with AErosol Robotic Network (AERONET) data shows a correlation coefficient of 0.75. The AODs retrieved from AATSR using the DVMS approach and those obtained from AERONET data show similar temporal trends, but the AERONET results are more variable and the highest AOD values are mostly missed by the DVMS approach. Limitations of the DVMS method are discussed. The pure-snow BRDF model needs further correction in order to obtain a better estimation for mixtures of snow and ice. © 2013 Copyright 2013 Taylor & Francis.

Particulate matter poses a significant threat to human health. To be able to develop effective mitigation strategies, the origin of particulate matter needs to be established. The regional air quality model LOTOS-EUROS, equipped with a newly developed labeling routine, was used to establish the origin of PM10 and PM2.5 in the Netherlands for 2007-2009 at the source sector level, distinguishing between national and foreign sources. The results suggest that 70-80% of modeled PM10 and 80-95% of PM2.5 in the Netherlands is of anthropogenic origin. About 1/3 of anthropogenic PM10 is of Dutch origin and 2/3 originates in foreign countries. Agriculture and transport are the Dutch sectors with the largest contribution to PM10 mass in the Netherlands, whereas the foreign contribution is more equally apportioned to road transport, other transport, industry, power generation and agriculture. For the PM2.5 fraction, a larger share is apportioned to foreign and anthropogenic origin than for PM10, but the same source sectors are dominant. The national contribution to PM levels is significantly higher in the densely populated Randstad area than for the country on average and areas close to the borders. In general, the Dutch contribution to the concentration of primary aerosol is larger than for secondary species. The sectoral origin varies per component and is location and time dependent. During peak episodes, natural sources are less important than under normal conditions, whereas especially road transport and agriculture become more important. © 2012 Elsevier Ltd.

For risk analysis studies, relatively simple dispersion models are generally applied, such as Gaussian dispersion and dense gas dispersion models. For rail transport risk analyses in the Netherlands, fixed consequence distances are applied for various standard scenarios of hazardous materials releases. The advantage is that the results are uniform and are relatively independent of the party performing the calculations, which facilitates the decision making. The drawback of this method, however, is that the results are mostly (very) conservative and the implementation of safety measures cannot be taken into account. The use of CFD enables to account for local topography of the buildings in a city and additionally enables the investigation of safety measures. This paper describes the use of CFD for a hazardous material release in Tilburg city. The first scenario follows from the standard scenarios for rail transport in the Netherlands as given in guidelines for risk analysis as well as the RBM-II software. The paper describes how the CFD model is set-up for an urban environment and the results are compared to the standard risk analysis scenario. The advantages and disadvantages of both CFD and standard risk analysis methods are discussed. A second scenario is a dense gas release in the same area, which is not part of the standard scenarios. The CFD results for this scenario are compared to wind tunnel experiments.

In this paper we will present the FP7-project 'MarcoPolo'. The main objective of MarcoPolo is to improve air quality monitoring, modelling and forecasting over China using satellite data. During the project a new emission inventory will be constructed by combining Chinese and European expertise. It will be based on recent satellite data and GIS information. Due to the strong economic growth in the China in the past decade, air pollution has become a serious issue in many parts of the country. For this reason up-to-date regional air pollution information and means of emission control for the main pollutants are becoming more and more important. Within a previous FP6-project, 'Air Quality Monitoring and Forecasting in China' (AMFIC), atmospheric environmental monitoring over China was addressed by a team of both Chinese and European scientists. Within AMFIC it was concluded that modelling of air quality and therefore the forecast capabilities are hampered by the rapidly changing emission data due to economic growth. In addition, air quality measures could not directly be related to changes in emissions. Therefore, within this follow-up project, MarcoPolo, the focus will be placed on emission estimates from space and the refinement of these emission estimates by spatial downscaling and by source sector apportionment. A wide range of satellite data will be used from various satellite instruments. From these satellite data, emission estimates will be made for NOx, S02, PM and biogenic sources. With various state-of-the-art techniques, emission inventories will be created and compared. By combining these emission data with known information from the ground, a new emission database for MarcoPolo will be constructed. The improved emission inventory is input to regional air quality models. Within MarcoPolo we will have a monthly update of the emissions based on the latest satellite observations. This will improve the existing air quality modelling and forecasts. We will demonstrate the resulting air quality information by running models on both meso- and urban scale. End-users and decision makers will be informed about air quality via visualized model results and forecasts. ©2013 by the International Astronautical Federation. All rights reserved. Organisation

The causes of renewed growth in the atmospheric CH4 burden since 2007 are still poorly understood and subject of intensive scientific discussion. We present a reanalysis of global CH4 emissions during the 2000s, based on the TM5-4DVAR inverse modeling system. The model is optimized using high-accuracy surface observations from NOAA ESRL's global air sampling network for 2000-2010 combined with retrievals of column-averaged CH4 mole fractions from SCIAMACHY onboard ENVISAT (starting 2003).Using climatological OH fields, derived global total emissions for 2007-2010 are 16-20 Tg CH 4/yr higher compared to 2003-2005. Most of the inferred emission increase was located in the tropics (9-14 Tg CH4/yr) and mid-latitudes of the northern hemisphere (6-8 Tg CH4/yr), while no significant trend was derived for Arctic latitudes. The atmospheric increase can be attributed mainly to increased anthropogenic emissions, but the derived trend is significantly smaller than estimated in the EDGARv4.2 emission inventory. Superimposed on the increasing trend in anthropogenic CH4 emissions are significant inter-annual variations (IAV) of emissions from wetlands (up to ±10 Tg CH4/yr), and biomass burning (up to ±7 Tg CH4/yr). Sensitivity experiments, which investigated the impact of the SCIAMACHY observations (versus inversions using only surface observations), of the OH fields used, and of a priori emission inventories, resulted in differences in the detailed latitudinal attribution of CH4 emissions, but the IAV and trends aggregated over larger latitude bands were reasonably robust. All sensitivity experiments show similar performance against independent shipboard and airborne observations used for validation, except over Amazonia where satellite retrievals improved agreement with observations in the free troposphere. Key Points A reanalysis of global CH4 emissions during the 2000s is presented derived global total emissions 2007-2010 16-20 Tg CH4/yr higher than 2003-2005 increase mainly in the tropics and NH mid-latitudes ©2013. American Geophysical Union. All Rights Reserved.

The atmospheric concentration of elemental carbon (EC) in Europe during the six-year period 2005-2010 has been simulated with the EMEP MSC-W model. The model bias compared to EC measurements was less than 20% for most of the examined sites. The model results suggest that fossil fuel combustion is the dominant source of EC in most of Europe but that there are important contributions also from residential wood burning during the cold seasons and, during certain episodes, also from open biomass burning (wildfires and agricultural fires). The modelled contributions from open biomass fires to ground level concentrations of EC were small at the sites included in the present study, EC measurements and modelled EC were also compared to optical measurements of black carbon (BC). The relationships between EC and BC (as given by mass absorption cross section, MAC, values) differed widely between the sites, and the correlation between observed EC and BC is sometimes poor, making it difficult to compare results using the two techniques and limiting the comparability of BC measurements to model EC results. A new bottom-up emission inventory for carbonaceous aerosol from residential wood combustion has been applied. For some countries the new inventory has substantially different EC emissions compared to earlier estimates. For northern Europe the most significant changes are much lower emissions in Norway and higher emissions in neighbouring Sweden and Finland. For Norway and Sweden, comparisons to source-apportionment data from winter campaigns indicate that the new inventory may improve model-calculated EC from wood burning. Finally, three different model setups were tested with variable atmospheric lifetimes of EC in order to evaluate the model sensitivity to the assumptions regarding hygroscopicity and atmospheric ageing of EC. The standard ageing scheme leads to a rapid transformation of the emitted hydrophobic EC to hygroscopic particles, and generates similar results when assuming that all EC is aged at the point of emission. Assuming hydrophobic emissions and no ageing leads to higher EC concentrations. For the more remote sites, the observed EC concentration was in between the modelled EC using standard ageing and the scenario treating EC as hydrophobic. This could indicate too-rapid EC ageing in the model in relatively clean parts of the atmosphere. © Author(s) 2013. CC Attribution 3.0 License.

Air–liquid interface (ALI) exposures enable in vitro testing ofmixtures of gases and particles such as diesel exhaust (DE). The main objective of this study was to investigate the feasibility of exposing human lung epithelial cells at the ALI to complete DE generated by a heavy-duty truck in the state-of-the-art TNO powertrain test center. A549 cells were exposed at the air–liquid interface to DE generated by a heavy-duty Euro III truck for 1.5 h. The truck was tested at a speed of 70 km/h-1 to stimulate free-flowing traffic on a motorway. Twenty-four hours after exposure, cells were analyzed for markers of oxidative stress (GSH and HO-1), cytotoxicity (LDH) and Alamar Blue assay) and inflammation (IL-8). DE exposure resulted in an increased oxidative stress response (significantly increased HO-1 levels and significantly reduced GSH/GSSH ratio), and a decreased cell viability (significantly decreased Alamar Blue levels and slightly increased LDH levels). However, the pro-inflammatory response seemed to decrease (decrease in IL-8). The results presented here demonstrate that we are able to successfully expose A549 cells at ALI to complete DE generated by a heavy-duty truck in TNO’s powertrain test center and show oxidative stress and cytotoxicity responses due to DE exposure

Aanvullend onderzoek laat zien dat er binnen steden grote ruimtelijke concentratieverschillen zijn voor roet en zware metalen

This study examines the role of horizontal grid resolution on the performance of the regional three dimensional chemical transport model (CTM) PMCAMx. Two cases were investigated. First, the model was applied over the Northeastern United States with grid resolutions of 36 and 12 km during both a summer and a winter period. In this case the emission inventory was simply interpolated from the low resolution version. In the second case a multi-scale 36/4 km grid resolution is used over Western Europe with high resolution (4 × 4 km) emissions. The improvement in model predictions with the fine grid is modest during the summer and more significant during wintertime at both domains. Major differences are predicted mostly for primary (organics and black carbon (BC)) rather than secondary (e.g. sulfate) species. The use of high grid resolution decreases the bias for BC concentration by more than 30% in the Northeastern US during wintertime. In the Megacity of Paris, using high resolution emissions and a 4-km grid decreases the fractional bias for organic aerosol (OA) from 80% to 60% in the city center and produces much larger spatial concentration gradients in the domain as compared to the emissions being interpolated. These results suggest that future work should combine high grid resolution with high resolution emissions, taking into consideration, though, that the grid resolution is not currently the major source of the discrepancies between model predictions and observations. © 2012 Elsevier Ltd.

This paper reports the development of a tool to assess the environmental performance of carbon dioxide capture and storage (CCS) chains. The environmental assessment is done for the whole CCS chain. The tool has been designed to produce transparent and traceable results and is easy to work with. The tool is meant for a broad group of stakeholders for assessing CCS chains on their environmental performance. It provides insights into the environmental performance of CCS chains by using a learning-by-doing experience for users. It allows both knowledge sharing and stakeholder engagement so that view points of stakeholders are better understood and decision making on the deployment of CCS can be improved.

Noise is pervasive in everyday life and can cause both auditory and non-auditory health eff ects. Noise-induced hearing loss remains highly prevalent in occupational settings, and is increasingly caused by social noise exposure (eg, through personal music players). Our understanding of molecular mechanisms involved in noise-induced haircell and nerve damage has substantially increased, and preventive and therapeutic drugs will probably become available within 10 years. Evidence of the non-auditory eff ects of environmental noise exposure on public health is growing. Observational and experimental studies have shown that noise exposure leads to annoyance, disturbs sleep and causes daytime sleepiness, aff ects patient outcomes and staff performance in hospitals, increases the occurrence of hypertension and cardiovascular disease, and impairs cognitive performance in schoolchildren. In this Review, we stress the importance of adequate noise prevention and mitigation strategies for public health

The development of a radiation fog layer at the Cabauw Experimental Site for Atmospheric Research(51.97°N, 4.93°E) on 23 March 2011 was observed with ground-based in situ and remote sensing observationsto investigate the relationship between visibility and radar reflectivity. The fog layer thickness was less than200 m. Radar reflectivity values did not exceed 225 dBZ even with visibilities less than 100 m. The onset andevaporation of fog produce different radar reflectivity-visibility relationships. The evolution of the fog layerwas modeled with a droplet activation model tha used the aerosol size distribution observed at the 60-m altitude tower level as input. Radar reflectivity and visibility were calculated from model drop ize spectra using Mie scattering theory. Since radiative cooling rates are small in comparison with cooling rates due to adiabatic lift of aerosol-laden air, the modeled supersaturation remains low so that few aerosol particles are activated to cloud droplets. The modeling results suggest that the different radar reflectivity-v sibility relationshipsare the result of differences in the interplay between water vapor and cloud droplets during formation and evaporation of the fog. During droplet activation, only a few large cloud droplets remain after successfully competing for water vapor with the smaller activated droplets. These small droplets eventually evaporate (deactivate) again. In the fog dissolution/evaporation stage, only these large droplet need to be evaporated.Therefore, to convert radar reflectivity to visibility for traffic safety products, knowledge of the state of local fog evolution is necessary. © 2013 American Meteorological Society.

In this article the method of environmental quickscans is introduced. This method is developed in the EU-funded project 'BioBuild'. The goal of BioBuild is to develop biocomposite building products with 50% reduction of embodied energy and no increase in costs, compared to current alternatives. To ensure that the developed products have this improved performance, environmental quickscans are executed for important design decisions related to fibre selection, fibre treatment, matrix selection, painting and coating of the building products. In this article the benefits and lessons learned of the environmental quickscan approach will be explained by using the quickscan on fibre treatment as an example. The quickscan indicates that the embodied energy of fibre treatment processes differs with a factor 6. This shows that investigating the environmental impact of production options is of importance as the options can differ substantially in environmental performance. © 2013 Taylor & Francis Group.

Five air quality models were applied over Portugal for July 2006 and used as ensemble members. Each model was used, with its original set up in terms of meteorology, parameterizations, boundary conditions and chemical mechanisms, but with the same emission data. The validation of the individual models and the ensemble of ozone (O3) and particulate matter (PM) is performed using monitoring data from 22 background sites. The ensemble approach, based on the mean and median of the five models, did not improve significantly the skill scores due to large deviations in each ensemble member. Different bias correction techniques, including a subtraction of the mean bias and a multiplicative ratio adjustment, were implemented and analysed. The obtained datasets were compared against the individual modelled outputs using the bias, the root mean square error (RMSE) and the correlation coefficient. The applied bias correction techniques also improved the skill of the individual models and work equally well over the entire range of observed O3 and PM values. The obtained results revealed that the best bias correction technique was the ratio adjustment with a 4-day training period, demonstrating significant improvements for both analysed pollutants. The increase in the ensemble skill found comprehends a bias reduction of 88 % for O3, and 92 % for PM10, and also a decrease in 23 % for O3 and 43 % for PM10 in what concerns the RMSE. In addition, a spatial bias correction approach was also examined with successful skills comparing to the uncorrected ensemble for both pollutants. © 2013 Springer Science+Business Media Dordrecht.

There are emerging concerns about potential effects on child health and development of early-life exposure to substances such as brominated flame retardants (BFRs), perfluorinated compounds (PFCs), phthalates and phenols (including bisphenol A (BPA)); pregnancy and birth cohort studies are ideally designed to study such concerns prospectively. As part of the ENRIECO project, we evaluated existing human biomonitoring data for these substances in European birth cohorts and develop recommendations for more harmonized methods that will enable combination and comparison of cohort data in the future. The ENRIECO inventory shows that 20 European birth cohorts have measured or are measuring BFRs (N=10), PFCs (N=11), phthalates (N=16) or phenols (N=8). Generally, samples were collected prenatally or at birth and measurements involved few subjects in each cohort (a few hundred maximum). Biological matrices, timing, and analytical methods of the measurements varied between cohorts. Few cohorts have measured at multiple time points or in children. In European cohorts, levels of BFRs were very low and at least 10-fold lower than in US; levels of PFCs and phthalates have decreased over the last decade since the phasing out of certain of these compounds; concentrations of phenols are comparable to those in the US. Although there is little published data in the cohorts now, many measurements are ongoing and we recommend that cohorts start working towards combined and comparison studies. Specific recommendations for use of existing data include the development of conversion models for the different media used for measurement of persistent chemicals, and inter-laboratory comparisons and calibrations. Recommendations for further data collection include more evaluation of exposure to these chemicals in children; repeated measurements of non-persistent chemicals; validation and harmonisation of questionnaires; and the development of mechanisms for fast European birth cohort response for the detection and prioritisation of new chemicals of concern. © 2012 Elsevier GmbH.

Noise mapping models are able to accurately predict directly exposed facade levels near busy roads on condition that sufäciently detailed trafäc data is available. At the non-directly exposed side ofthe building, howeve¡ common practice application of standard methods strongly underpredicts sound pressure levels, potentially leading to an incorrect assessment of noise annoyance and sleep disturbance. The concept of background noise mapping was proposed before, which has the important advantage that it can increase the accuracy of existing noise maps at a limited computational cost. In this study, long-term meteorological and noise data showed that turbulence scattering contributes significantly to the noise level at shielded facades, already at sound frequencies below I kHz. Periods with strong atmospheric turbulence are dominant for long-term equivalent noise levels as typically used in strategic noise maps. A comparison between predictions and measurements show that rather high turbulence strengths should be used when producing noise maps

Traffic noise and air pollution have been associated with cardiovascular health effects. Until date, only a limited amount of prospective epidemiological studies is available on long-term effects of road traffic noise and combustion related air pollution. This study investigates the relationship between road traffic noise and air pollution and hospital admissions for ischemic heart disease (IHD: International Classification of Diseases (ICD9) 410-414) or cerebrovascular disease (cerebrovascular event [CVE]: ICD9 430-438). We linked baseline questionnaire data to 13 years of follow-up on hospital admissions and road traffic noise and air pollution exposure, for a large random sample (N = 18,213) of inhabitants of the Eindhoven region, Netherlands. Subjects with cardiovascular event during follow-up on average had higher road traffic noise day, evening, night level (Lden) and air pollution exposure at the home. After adjustment for confounders (age, sex, body mass index, smoking, education, exercise, marital status, alcohol use, work situation, financial difficulties), increased exposure did not exert a significant increased risk of hospital admission for IHD or cerebrovascular disease. Relative risks (RRs) for a 5th to 95th percentile interval increase were 1.03 (0.88-1.20) for Lden; 1.04 (0.90-1.21) for particulate matter (PM10); 1.05 (0.91-1.20) for elemental carbon (EC); and 1.12 (096-1.32) for nitrogen dioxide (NO2) in the full model. While the risk estimate seemed highest for NO2, for a 5th to 95th percentile interval increase, expressed as RRs per 1 μg/m3 increases, hazard ratios seemed highest for EC (RR 1.04 [0.92-1.18]). In the subgroup of study participants with a history of cardiovascular disease, RR estimates seemed highest for noise exposure (1.19 [0.87-1.64] for Lden); in the subgroup of elderly RR seemed highest for air pollution exposure (RR 1.24 [0.93-1.66] for NO2).

Previous studies indicate that residents may benefit from a "quiet side" to their dwellings. The influence of the level of road traffic noise exposure at the least exposed side on road traffic noise annoyance was studied in Amsterdam, The Netherlands. Road traffic noise exposure was assessed at the most and least exposed façade (Lden,most and Lden least respectively) of dwellings for subjects in a population based survey (N = 1,967). It was investigated if and to what extent relative quietness at the least exposed façade affected the level of road traffic noise annoyance by comparing two groups: (1) The subgroup with a relatively quiet façade; (2) the subgroup without a relatively quiet façade (large versus small difference in exposure between most and least exposed façade; DIF ≥ 10 dB and DIF < 10 dB respectively). In addition, it was investigated if and to what extent Lden,leastaffected the level of road traffic noise annoyance. Results indicate a significantly lower road traffic noise annoyance score at a given Lden,most in the subgroup with DIF ≥ 10 dB versus DIF < 10 dB. Furthermore, results suggest an effect of Lden,leastindependent of Lden,most. The estimated size of the effect expressed in an equivalent change in Lden,most approximated 5 dB for both the difference between the two subgroups (DIF ≥ 10 dB and DIF < 10 dB), and for a 10 dB change in Lden,least. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

The regular eastward drift of transboundary aerosol intrusions from the Asian mainland into the NW Pacific region has a pervasive impact on air quality in Japan, especially during springtime. Analysis of 24-h filter samples with Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Mass Spectrometry (ICP-MS), and hourly Streaker with Particle Induced X-ray Emission (PIXE) samples collected continuously for six weeks reveal the chemistry of successive waves of natural mineral desert dust ("Kosa) and metalliferous sulphatic pollutants arriving in western Japan during spring 2011. The main aerosol sources recognised by Positive Matrix Factorization (PMF) analysis of Streaker data are mineral dust and fresh sea salt (both mostly in the coarser fraction PM2.5-10), As-bearing sulphatic aerosol (PM 0.1-2.5), metalliferous sodic particulate matter (PM) interpreted as aged, industrially contaminated marine aerosol, and ZnCu-bearing aerosols. Whereas mineral dust arrivals are typically highly transient, peaking over a few hours, sulphatic intrusions build up and decline more slowly, and are accompanied by notable rises in ambient concentrations of metallic trace elements such as Pb, As, Zn, Sn and Cd. The magnitude of the loss in regional air quality due to the spread and persistence of pollution from mainland Asia is especially clear when cleansing oceanic air advects westward across Japan, removing the continental influence and reducing concentrations of the undesirable metalliferous pollutants by over 90%. Our new chemical database, especially the Streaker data, demonstrates the rapidly changing complexity of ambient air inhaled during these transboundary events, and implicates Chinese coal combustion as the main source of the anthropogenic aerosol component. © Author(s) 2013.

Road transport emissions are a major contributor to ambient particulate matter concentrations and have been associated with adverse health effects. Therefore, these emissions are targeted through increasingly stringent European emission standards. These policies succeed in reducing exhaust emissions, but do not address "nonexhaust" emissions from brake wear, tire wear, road wear, and suspension in air of road dust.Is this a problem? To what extent do nonexhaust emissions contribute to ambient concentrations of PM10 or PM2.5? In the near future, wear emissions may dominate the remaining traffic-related PM10 emissions in Europe, mostly due to the steep decrease in PM exhaust emissions. This underlines the need to determine the relevance of the wear emissions as a contribution to the existing ambient PM concentrations, and the need to assess the health risks related to wear particles, which has not yet received much attention. During a workshop in 2011, available knowledge was reported and evaluated so as to draw conclusions on the relevance of traffic-related wear emissions for air quality policy development. On the basis of available evidence, which is briefly presented in this paper, it was concluded that nonexhaust emissions and in particular suspension in air of road dust are major contributors to exceedances at street locations of the PM10 air quality standards in various European cities. Furthermore, wear-related PM emissions that contain high concentrations of metals may (despite their limited contribution to the mass of nonexhaust emissions) cause significant health risks for the population, especially those living near intensely trafficked locations. To quantify the existing health risks, targeted research is required on wear emissions, their dispersion in urban areas, population exposure, and its effects on health. Such information will be crucial for environmental policymakers as an input for discussions on the need to develop control strategies.Road transport particulate matter (PM) emissions are associated with adverse health effects. Stringent policies succeed in reducing the exhaust PM emissions, but do not address "nonexhaust" emissions from brake wear, tire wear, road wear, and suspension in air of road dust. In the near future the nonexhaust emissions will dominate the road transport PM emissions. Based on the limited available evidence, it is argued that dedicated research is required on nonexhaust emissions and dispersion to urban areas from both an air quality and a public health perspective. The implicated message to regulators and policy makers is that road transport emissions continue to be an issue for health and air quality, despite the encouraging rapid decrease of tailpipe exhaust emissions.Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association. © 2013 Copyright 2013 A&WMA.

The Arctic is vulnerable to the long-term transport of aerosols because they affect the surface albedo when particles are deposited on snow and ice. However, aerosol observations for this area are sparse and hence there is considerable uncertainty in the knowledge on the properties of the Arctic aerosol. Atmospheric remote sensing using satellite-based instruments offers an opportunity to obtain information on aerosol properties, in particular the aerosol optical depth (AOD) on an extended spatial scale as determined by the instrument's swath width. However, AOD retrieval over a bright surface is a difficult task because it is difficult to separate and explicitly describe the contribution of the surface and that due to back-scattering by aerosols to the radiance observed by a satellite at the top of the atmosphere (TOA), especially at large Solar Zenith Angles (SZA). In this paper, an approach to achieve this is presented based on a synergetic approach using data from both Moderate Resolution Imaging Spectroradiometer (MODIS) instruments flying on the TERRA and AQUA satellites. The approached also uses prior knowledge for aerosol properties retrieval over snow as well as a Snow Bidirectional Reflectance Distribution Function (BRDF) model. The detailed analysis of the model results demonstrates that the Aerosol Properties Retrieval over Snow (APRS) algorithm is suitable for Arctic region Aerosol Optical Depth (AOD) retrieval. The study periods include April 2010 and April 2011, when the Arctic haze mostly occurs. Six AERONET stations at high latitude (Andenes, Barrow, Ittoqqortoormiit, OPAL, Thule, and PEARL) were used for comparison. The correlation coefficient between retrieved AODs and AERONET AODs was 0.8 and the relative error is between 10% and 20%, demonstrating the potential of the APRS method to retrieve AOD over the Arctic, with highly reflective snow/ice surfaces and large solar zenith angles. © 2012 Elsevier Inc.

Uitdagingen genoeg om de luchtkwaliteit in Nederland en Europa te verbeteren. Niet alleen fijnstof en stikstof, maar ook ozon en NMVOS-emissies vormen nog een probleem, stellen onderzoekers van het PBL (Planbureau voor de Leemomgeving) en TNO. Gelukkige bijkomstigheid: het Europese klimaatbeleid levert een betere luchtkwaliteit op

Under warm and dry conditions, ammonium nitrate aerosol outgasses to form ammonia and nitric acid in the lower atmospheric boundary layer. In the upper boundary layer, where the temperature is lower and the relative humidity is higher, nitric acid and ammonia condense back to the aerosol phase. Measurements show that aerosol nitrate mixing ratios increase with altitude, confirming this phase transition. Since phase equilibrium is not reached instantaneously, updrafts transport aerosol-poor air from the surface to high altitudes and aerosol-rich air subsides from high altitudes to the surface under turbulent conditions. As a result, the partitioning deviates from equilibrium, so the horizontal and temporal variabilities of the aerosol nitrate mixing ratio are enhanced and a continuous downward aerosol nitrate flux emerges. We postulate that observations of this variability and flux should not be interpreted as instrument noise and deposition of nitrate. In an idealized large-eddy simulation (LES) experiment of a convective boundary layer, we find that the larger variability and flux occurred at about one third of the boundary layer height. Both are largest when the gas-aerosol partitioning time scale is assumed to be about half the time scale of turbulence. Our LES result shows negatively skewed nitrate mixing ratios. Under colder conditions, a smaller fraction of ammonium nitrate aerosol outgasses at the surface, so the absolute effect of nitrate repartitioning becomes smaller. However, dimensionless statistical properties do not change as long as the turbulent properties of the boundary layer remain similar. This indicates that the identified processes are also present under colder conditions. © 2012. American Geophysical Union.

A reliable emissions inventory is highly important for air quality modelling applications, especially at regional or local scales, which require high resolutions. Consequently, higher resolution emission inventories have been developed that are suitable for regional air quality modelling.This research performs an inter-comparative analysis of different spatial disaggregation methodologies of atmospheric emission inventories. This study is based on two different European emission inventories with different spatial resolutions: 1) the EMEP (European Monitoring and Evaluation Programme) inventory and 2) an emission inventory developed by the TNO (Netherlands Organisation for Applied Scientific Research). These two emission inventories were converted into three distinct gridded emission datasets as follows: (i) the EMEP emission inventory was disaggregated by area (EMEParea) and (ii) following a more complex methodology (HERMES-DIS - High-Elective Resolution Modelling Emissions System - DISaggregation module) to understand and evaluate the influence of different disaggregation methods; and (iii) the TNO gridded emissions, which are based on different emission data sources and different disaggregation methods. A predefined common grid with a spatial resolution of 12×12km2 was used to compare the three datasets spatially.The inter-comparative analysis was performed by source sector (SNAP - Selected Nomenclature for Air Pollution) with emission totals for selected pollutants. It included the computation of difference maps (to focus on the spatial variability of emission differences) and a linear regression analysis to calculate the coefficients of determination and to quantitatively measure differences.From the spatial analysis, greater differences were found for residential/commercial combustion (SNAP02), solvent use (SNAP06) and road transport (SNAP07). These findings were related to the different spatial disaggregation that was conducted by the TNO and HERMES-DIS for the first two sectors and to the distinct data sources that were used by the TNO and HERMES-DIS for road transport.Regarding the regression analysis, the greatest correlation occurred between the EMEParea and HERMES-DIS because the latter is derived from the first, which does not occur for the TNO emissions. The greatest correlations were encountered for agriculture NH3 emissions, due to the common use of the CORINE Land Cover database for disaggregation. The point source emissions (energy industries, industrial processes, industrial combustion and extraction/distribution of fossil fuels) resulted in the lowest coefficients of determination. The spatial variability of SOx differed among the emissions that were obtained from the different disaggregation methods.In conclusion, HERMES-DIS and TNO are two distinct emission inventories, both very well discretized and detailed, suitable for air quality modelling. However, the different databases and distinct disaggregation methodologies that were used certainly result in different spatial emission patterns. This fact should be considered when applying regional atmospheric chemical transport models. Future work will focus on the evaluation of air quality models performance and sensitivity to these spatial discrepancies in emission inventories. Air quality modelling will benefit from the availability of appropriate resolution, consistent and reliable emission inventories. © 2013 Elsevier Ltd.

Restwarmte van bedrijven in het stedelijke gebied wordt veelal rechtstreeks geëmitteerd naar de omgeving, Vooral in de winterperiode kan deze warmte door derden benut worden voor verwarmingsdoeleinden. Dit geldt bijvoorbeeld voor de vrijkomende condensatiewarmte van koelinstallaties van ziekenhuizen en supermarkten. Hiermee kunnen honderden woningen in de directe omgeving worden verwarmd

An experimental test set up has been constructed to carry out controlled CO2 release experiments from a high pressure vessel. The test set up is made up of a 500l stainless steel vessel where CO2 can be introduced up to high pressures and where controlled releases can be conducted. The work objective is to get experimental data that help to understand the thermo-hydraulic behavior of CO2 when discharged from a pressurized vessel and to further improve and validate existing and newly developed release and dispersion models. The aim is to get better insight into the fluid behavior in the vessel as well as in the discharged jet, and to understand the relation between the thermodynamic regime inside the high pressure medium and the mass release rate and jet zone characteristics during the release process.In this experimental work, the impact of varying the release orifice diameter and the initial vessel pressure on the CO2 discharge will be examined and analyzed, and the different thermodynamic regimes inside and outside the high pressure medium will be described and interpreted. © 2013 Elsevier Ltd.

The EU-project CargoVibes aims to describe the expected annoyance due to vibration among residents living near (freight) railway lines. Compared to the state of knowledge on the annoyance response to noise, relatively little is known about the relationship between vibration exposure and annoyance. Existing evaluation criteria in use are not consistent and not always based on relevant surveys. Although in several countries surveys were done on railway-induced vibration, the results are not readily comparable due to the use of different exposure metrics. In the present study, a meta-analysis was done on all available exposure-response datasets from railway vibration surveys, eight in total including two new surveys. A statistical method taking into account the multilevel structure of the sample was used, and a conversion matrix was developed that allows to convert different vibration metrics into each other. Despite differentiation in the annoyance response between studies, partly explained by source of vibration, an exposure-response relationship could be derived, showing the expected percentage ofresidents annoyed or highly annoyed at a given vibration level. This exposure-response relationship may form the basis of criteria for the evaluation of adverse eflects of railway vibration.