New tools for assessing personal exposure near urban air pollution hotspots

During the last decade, researchers and policy makers have focused on the development and deployment of air pollution mitigation measures invoking solutions based on technology transfer. This term encompasses the synthesis of air quality monitoring, primarily by networks of inexpensive sensors, remote sensing and numerical modelling, as tools for supporting policy makers and disseminating air quality information to the citizens. It has been recognised that localised concentration maxima developing around traffic sources represent an exposure contribution of major epidemiological significance. The ability, therefore, of an integrated air quality management system to reliably assess personal exposure heavily depends on the consistent numerical treatment of multiscale interactions which determine the flow and dispersion structures in these fine spatial scales. Moreover, it is important to incorporate innovative methodologies for enhancing the stability and error-resilience of the sensor networks themselves. The approach presented in this work focuses on the utilisation of latest developments both in sensor technology and numerical air quality modelling, so as to provide end products able to support regulatory assessment and environmental information services. A peer-to-peer network of air quality measuring devices is deployed in six urban areas in the Balkan region in order to provide real time air quality data over areas of high population and emissions density. The coupled mesoscale modelling system MEMO/ MARS-aero and the mesomicro MEMICO two-way coupling methodology implement the physical modelling core of the system in the respective spatial scales. These modelling tools are used to estimate, integrate and complement the sensor data on pollutant levels in predictions of high temporal and spatial resolution in order to highlight pollution hot spots. In the case of fine particulate matter, special adaptations are incorporated in the emissions and chemical transformation treatment in order to provide consistent number concentration fields, which constitute the most relevant exposure metric

THE EFFECT OF SOURCE TREATMENT ON POLLUTANT DISPERSION IN AN IDEALISED URBAN ROUGHNESS IN NUMERICAL SIMULATIONS USING THE STANDARD k-ε TURBULENCE CLOSURE MODEL

The need for accurate model predictions in urban air quality assessment studies during the past decade has led to the ever increasing use of Computational Fluid Dynamics (CFD) models in order to resolve the various local scale inhomogeneities which dominate flow and dispersion and are usually encountered in urban areas. Towards the aim of improving model predicted dispersion via the use of CFD models, a numerical study was undertaken in order to investigate the effect of different techniques applied for treating the sources of emissions on the near source behaviour of the models, as well as on the actual predicted concentrations at locations away from the vicinity of the sources under consideration. A series of 3D numerical simulations were performed for the wind tunnel model geometry of the Mock Urban Setting Test (MUST) field experiment of the University of Hamburg, Meteorological Institute, Division of Technical Meteorology, which was made available within the frame of COST Action 732. Overall in conclusion, results show that depending on the type of source, the intensity of the vertical component of the emissions exit velocity at the source and the mesh refinement close to source boundaries predicted concentrations can deviate significantly from the wind tunnel measurements. However, it is possible to partially improve the performance of a CFD model in urban dispersion problems, mainly via the application of the proper combination of these parameters

A METAMODELLING IMPLEMENTATION OF A TWO-WAY COUPLED MESOSCALE-MICROSCALE FLOW MODEL FOR URBAN AREA SIMULATIONS

Systems of coupled prognostic mesoscale and microscale models have been used as a tool to accurately simulate flows around artificial structures and over densely-built urban areas. Typical implementations of such systems are based on a one-way coupling scheme, where the mesoscale model provides initial and boundary conditions for each off-line application of the microscale model. While very successful in predicting steady-state flows within specific local-scale areas, such schemes fail to account for feedbacks on the mesoscale flow induced by the presence of structures in smaller scales. Unfortunately, the large gap of spatial and temporal scales practically prohibits parallel on-line execution of the mesoscale and microscale models for any significant time interval. It is therefore necessary that a simplifying approach is adopted, where the microscale feedback is spatially and temporally upscaled to interact with parts of the mesoscale domain covering the urban area. In the present work a two-way coupled model system is developed, consisting of the prognostic mesoscale model MEMO and the microscale model MIMO. The microscale feedback on the mesoscale domain is simulated using a metamodelling approach, where the effect of local flows on the vertical profiles is estimated for representative urban areas of sizes up to a few hundred meters and used as calibration input for a set of interpolating metamodels. The feedback from the microscale metamodels is then introduced back in the mesoscale grid by means of Newtonian relaxation. As an illustrative application, simulations for the city of Athens, Greece during a multi-day period are presented. Effects of the microscale feedback on the mesoscale flow become evident both as a reduction of lower-level wind speeds in urban cells as well as an overall increase in turbulent kinetic energy production over densely-built areas

Modelling the dispersion of particle numbers in five European cities

We present an overview of the modelling of particle number concentrations (PNCs) in five major European cities, namely Helsinki, Oslo, London, Rotterdam, and Athens, in 2008. Novel emission inventories of particle numbers have been compiled both on urban and European scales. We used atmospheric dispersion modelling for PNCs in the five target cities and on a European scale, and evaluated the predicted results against available measured concentrations. In all the target cities, the concentrations of particle numbers (PNs) were mostly influenced by the emissions originating from local vehicular traffic. The influence of shipping and harbours was also significant for Helsinki, Oslo, Rotterdam, and Athens, but not for London. The influence of the aviation emissions in Athens was also notable. The regional background concentrations were clearly lower than the contributions originating from urban sources in Helsinki, Oslo, and Athens. The regional background was also lower than urban contributions in traffic environments in London, but higher or approximately equal to urban contributions in Rotterdam. It was numerically evaluated that the influence of coagulation and dry deposition on the predicted PNCs was substantial for the urban background in Oslo. The predicted and measured annual average PNCs in four cities agreed within approximatelyPeer reviewe

Identifying the optimal strategy for suppliers’ involvement in product design: A case study

In order to increase efficiency and improve competitiveness, manufacturers around the globe are focusing on developing their core businesses. On the other hand, standard activities of engineering are optimally accomplished outside the borders of the firm; thus outsourcing of non-core businesses has become lately a common practice. Product design is considered as one of the most important phases in a product’s life cycle, since the majority of most critical decisions in terms of products’ overall performance are considered during the Research & Development (R&D) phase. Involving suppliers in a firm’s R&D offers significant benefits in various directions, such as feasibility, practicability, sustainability, competitiveness and innovativeness. However, selecting the optimal outsourcing strategy is not an easy decision. On the contrary, it is most challenging since it encompasses a number of different and in many cases mutually conflicting criteria. This paper presents a methodological approach for the selection of the optimal outsourcing strategy for a manufacturer’s R&D. The methodology is based on outranking multicriteria methods and more specifically ELECTRE III. The approach is illustrated and validated through a real world case study of a Greek olive oil producer.   Keywords: product design; suppliers; R&D; outsourcing strategy; multicriteria analysis, ELECTRE II

Αir Quality in Urban Areas: Urban Air Pollutants, Combined Exposure Management and Planning

The “urban climate” is characterized by numerous environmental pressures such as air and noise pollution, toxic substances or radiation which give justifiable rise to citizens’ worries about possible impacts on public health. The effort to close the loop between health stressors in urban areas is scientifically of major importance and should be brought forward. This paper supports this initiative and presents an integrated exposure assessment for Thessaloniki, Greece. The approach is based on the application of the Combined Environmental Stressors’ Exposure (CENSE) tool. The area under consideration is a densely populated urban environment and presents high levels of environmental health stressors mainly due to the combination of large numbers of citizens and intense road traffic. CENSE is a tool for environmental integrated management on the grounds of the combined dose and exposure indicators theory for urban spaces. An urban space may be a closed environment (e.g. the interior of a car) as much as an open-air one (such as the saddle of a bicycle, or even the pavement used by pedestrians). The tool incorporates co-exposure indicators and takes into account the potential relative intake of each chemical stressor by considering the physical activities of each citizen (i.e. standing, walking, fast walking, cycling, fast cycling, car riding or motorcycle riding). The presented approach could be characterised as a little stepping stone to bridge the gap between numerous health stressors and to highlight their possible interactions and combined impact. Undoubtedly, the scientific gap and the inherent epidemiological uncertainties are significant, especially when considering combined or synergetic exposure to the complex environmental pollution mix. However, it is concluded that rather than viewing chemical and physical health stressors separately for decision making and environmental sustainability consideration and planning, the possibility of an easy-to-comprehend co-exposure assessment is considered with use of the CENSE application

MEGAPOLI: concept of multi-scale modelling of megacity impact on air quality and climate

The EU FP7 Project MEGAPOLI: "Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation" (http://megapoli.info) brings together leading European research groups, state-of-the-art scientific tools and key players from non-European countries to investigate the interactions among megacities, air quality and climate. MEGAPOLI bridges the spatial and temporal scales that connect local emissions, air quality and weather with global atmospheric chemistry and climate. The suggested concept of multi-scale integrated modelling of megacity impact on air quality and climate and vice versa is discussed in the paper. It requires considering different spatial and temporal dimensions: time scales from seconds and hours (to understand the interaction mechanisms) up to years and decades (to consider the climate effects); spatial resolutions: with model down- and up-scaling from street- to global-scale; and two-way interactions between meteorological and chemical processes