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GIORGIO VERATTI

Assegnista di ricerca
Dipartimento di Ingegneria "Enzo Ferrari"

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Pubblicazioni

2024 - Measurement report: Source attribution and estimation of black carbon levels in an urban hotspot of the central Po Valley: An integrated approach combining high-resolution dispersion modelling and micro-aethalometers [Articolo su rivista]
Veratti, Giorgio; Bigi, Alessandro; Stortini, Michele; Teggi, Sergio; Ghermandi, Grazia
abstract

Understanding black carbon (BC) levels and their sources in urban environments is of paramount importance due to their far-reaching health, climate and air quality implications. While several recent studies have assessed BC concentrations at specific fixed urban locations, there is a notable lack of knowledge in the existing literature on spatially resolved data alongside source estimation methods. This study aims to fill this gap by conducting a comprehensive investigation of BC levels and sources in Modena (Po Valley, Italy), which serves as a representative example of a medium-sized urban area in Europe. Using a combination of multi-wavelength micro-aethalometer measurements and a hybrid Eulerian-Lagrangian modelling system, we studied two consecutive winter seasons (February–March 2020 and December 2020–January 2021). Leveraging the multi-wavelength absorption analyser (MWAA) model, we differentiate sources (fossil fuel combustion, FF, and biomass burning, BB) and components (BC vs. brown carbon, BrC) from micro-aethalometer measurements. The analysis reveals consistent, minimal diurnal variability in BrC absorption, in contrast to FF-related sources, which exhibit distinctive diurnal peaks during rush hours, while BB sources show less diurnal variation. The city itself contributes significantly to BC concentrations (52 % ± 10 %), with BB and FF playing a prominent role (35 % ± 15 % and 9 % ± 4 %, respectively). Long-distance transport also influences BC concentrations, especially in the case of BB and FF emissions, with 28 % ± 1 % and 15 % ± 2 %, respectively. When analysing the traffic related concentrations, Euro 4 diesel passenger cars considerably contribute to the exhaust emissions. These results provide valuable insights for policy makers and urban planners to manage BC levels in medium-sized urban areas, taking into account local and long-distance sources.

2023 - Aerosol absorption using in situ filter-based photometers and ground-based sun photometry in the Po Valley urban atmosphere [Articolo su rivista]
Bigi, Alessandro; Veratti, Giorgio; Andrews, Elisabeth; Collaud Coen, Martine; Guerrieri, Lorenzo; Bernardoni, Vera; Massabò, Dario; Ferrero, Luca; Teggi, Sergio; Ghermandi, Grazia
abstract

Light-absorbing aerosols (LAAs) are short-lived climate forcers with a significant impact on Earth’s radiative balance. LAAs include dust aerosols, black carbon (BC) and organic light-absorbing carbonaceous aerosol (collectively termed brown carbon, BrC), which have also been proven to be highly toxic. In this study, aerosol absorption at five wavelengths (ranging from ultraviolet to infrared) was monitored continuously using filter-based photometers during two winter seasons in 2020 and 2021 in the city of Modena (southern central Po Valley, northern Italy), at two regulatory air quality monitoring sites, along with other pollutants (coarse partic- ulate matter, PM 10; fine particulate matter, PM 2.5 ; O 3 ; NO; NO 2 ; and C 6 H 6 ) and the vehicular traffic rate. The aerosol optical depth (AOD) and other column aerosol optical properties were concurrently monitored at four wavelengths by an AErosol RObotic NETwork (AERONET) sun photometer under urban background conditions within Modena. In situ absorption levels were apportioned to both sources (fossil fuel and biomass burning) and species (BC and BrC), while columnar absorption was apportioned to BC, BrC and mineral dust. The combined analysis of the atmospheric aerosol and gas measurements and of the meteorological conditions (in situ and from the ERA5 reanalysis) identified the location of potential urban sources of BC and BrC, most likely related to traf- fic and biomass burning. In situ data show different diurnal/weekly patterns for BrC from biomass burning and BC from traffic, with minor differences between the background and the urban traffic conditions. AERONET version 3 absorption aerosol optical depth (AAOD) retrievals at four wavelengths allowed the estimation of the absorptive direct radiative effect due to LAAs over the same period under the reasonable assumption that the AOD signal is concentrated within the mixing layer. AERONET retrievals showed a modest correlation of columnar absorption with planetary boundary layer (PBL)-scaled in situ observations, although the correlation improved significantly during a desert dust transport event that affected both in situ aerosol and columnar ab- sorption, particularly in the blue spectrum range. A low correlation occurred between the contribution of BrC to aerosol absorption for the in situ and the columnar observations, with the BrC contribution being generally larger for in situ observations. Finally, evidence of a highly layered atmosphere during the study period, featur- ing significant spatial mixing and modest vertical mixing, was shown by ERA5-based atmospheric temperature profiles and by the large correlation of concurrent AERONET AOD retrievals in Modena and in Ispra (on the northwestern side of the Po Valley, ca. 225 km from Modena).

2023 - Impact of NOx and NH3 Emission Reduction on Particulate Matter across Po Valley: A LIFE-IP-PREPAIR Study [Articolo su rivista]
Veratti, Giorgio; Stortini, Michele; Amorati, Roberta; Bressan, Lidia; Giovannini, Giulia; Bande, Stefano; Bissardella, Francesca; Ghigo, Stefania; Angelino, Elisabetta; Colombo, Loris; Fossati, Giuseppe; Malvestiti, Giulia; Marongiu, Alessandro; Dalla Fontana, Alberto; Intini, Barbara; Pillon, Silvia
abstract

Air quality in Europe continues to remain poor in many areas, with regulation limits often exceeded by many countries. The EU Life-IP PREPAIR Project, involving administrations and environmental protection agencies of eight regions and three municipalities in Northern Italy and Slovenia, was designed to support the implementation of the regional air quality plans in the Po Valley, one of the most critical areas in Europe in terms of pollution levels. In this study, four air quality modelling systems, based on three chemical transport models (CHIMERE, FARM and CAMx) were applied over the Po Valley to assess the sensitivity of PM2.5 concentrations to NOx and NH3 emission reductions. These two precursors were reduced (individually and simultaneously) from 25% up to 75% for a total of 10 scenarios, aimed at identifying the most efficient emission reduction strategies and to assess the non-linear response of PM2.5 concentrations to precursor changes. The multi-model analysis shows that reductions across multiple emission sectors are necessary to achieve optimal results. In addition, the analysis of non-linearities revealed that during the cold season, the efficiency of PM2.5 abatement tends to increase by increasing the emission reductions, while during summertime, the same efficiency remains almost constant, or slightly decreases towards higher reduction strengths. Since the concentrations of PM2.5 are greater in winter than in summer, it is reasonable to infer that significant emission reductions should be planned to maximise reduction effectiveness.

2023 - Tracing Airborne Microplastics in Modena: results from the MicroTRACES project [Abstract in Atti di Convegno]
Veratti, Giorgio; Bigi, Alessandro; Teggi, Sergio; Ferrari, Valentina; Scaramelli, Marco; Righi, Sara; Simonini, Roberto; Prevedelli, Daniela; Bergami, Elisa; Ghermandi, Grazia
abstract

2022 - Air quality (PM10) scenarios resulting from the expansion of hydrogen fuel cell electric vehicle in Emilia-Romagna (Northern Italy) [Relazione in Atti di Convegno]
Fabbi, Sara; Veratti, Giorgio; Bigi, Alessandro; Ghermandi, Grazia
abstract

2022 - IMPATTO DELLA DIFFUSIONE DI VEICOLI ELETTRICI E A IDROGENO SULLE CONCENTRAZIONI DI PM10 IN EMILIA-ROMAGNA [Articolo su rivista]
Fabbi, Sara; Veratti, Giorgio; Bigi, Alessandro; Ghermandi, Grazia
abstract

PM10 is a critical pollutant for the air quality in Emilia Romagna, a Northern Italy region that includes a large part of the Po Valley. The atmospheric levels of PM10 are strongly affected by vehicular traffic emissions, due to fuel exhaust and also to tires, brake and road surface wear, and to road dust resuspension (non-exhaust emissions). This study presents atmospheric PM10 scenarios deriving from vehicular traffic emissions in Emilia Romagna as resulting in 2030 from the growth of the Fuel Cell Electric Vehicle (FCEV) and battery electric vehicles (BEV) fleet in the region. Both exhaust and non-exhaust vehicular emissions are considered, evaluated according to the most up-to-date regional bottom-up emission inventory, which attributes about 60% of total primary PM10 traffic emissions to wear processes. PM10 concentration maps for actual (2019) and 2030 scenarios are obtained by a Lagrangian dispersion model (PMSS). Preliminary results highlight the future impact on atmospheric PM10 from tires, brake and road surface wear produced by battery electric vehicles, due to their larger mass compared to FCEVs, which have smaller batteries and mass. These emissions will partially offset the lack of PM10 exhaust emissions for electric vehicles. Finally, the daily primary PM10 levels by traffic emissions simulated by PMSS and CHIMERE models were compared at specific sites relevant for the studied domain, i.e. the regulatory air quality monitoring stations, only for actual (2019) scenario.

2021 - A comparative study of mesoscale flow-field modelling in an Eastern Alpine region using WRF and GRAMM-SCI [Articolo su rivista]
Oettl, D; Veratti, G
abstract

Recently, the mesoscale model GRAMM-SCI has been further developed to make use of the freely available global ERA5 reanalysis dataset issued by the ECMWF. In this study, first results are discussed for the federal state of Styria, which is situated in the eastern Alps of Austria. Additional simulations were made with the mesoscale model WRF, which serve as a benchmark in this work. The model runs covered one week in summer and another one in winter dominated by fair weather conditions. These were characterized by the development of complex mountain wind systems in the Alps, which play an important role for the dispersion of pollutants. Regarding the bias and the root mean square error both models perform very well in comparison with existing studies for Alpine areas and are able to capture the main features of observed surface flows such as valley-wind systems or katabatic flows at slopes. In addition, observed calm wind conditions at many stations during the winter period were reproduced by the models. However, the correct simulation of wind directions in these conditions was found to be extremely challenging. Existing model quality criteria for wind direction seem to be too strict for low-wind-speed conditions. Therefore, based on theoretical and empirical considerations, a new model evaluation benchmark for wind direction is proposed, which takes into account the random nature of horizontally meandering flows in stagnant weather situations.

2021 - PMSS and gral inter-comparison: Strengths and weaknesses of the two models in reproducing Urban NOx levels in a real case application [Relazione in Atti di Convegno]
Veratti, G.; Bigi, A.; Fabbi, S.; Ghermandi, G.
abstract

Air dispersion models are useful tools for quantifying pollutant concentrations in urban environment however many issues related to the dispersion estimation within urban canopy still persist. Most of them concern the emissions estimation, the flow field reconstruction between obstacles (buildings, bridges, tunnels, etc.) and the pollutant dispersion driven by the estimated flow field. This study presents results of a model inter-comparison conducted in a real case study, focusing on a 6 km x 6 km square domain covering the city of Modena (Italy), between two Lagrangian dispersion models set-up with the aim of estimating the NOx concentrations produced by traffic flow within the urban area of the city. Comparisons are made between the Graz Lagrangian Model (a.k.a. GRAL) and the Parallel Micro SWIFT and SPRAY (a.k.a. PMSS) modelling suite, in terms of dispersion concentrations and computing cost. The horizontal resolution for both the models is set to 4 meters and the traffic emissions estimation is based on a bottom-up approach: the PTV VISUM traffic model is used to estimate traffic flows on the Modena urban road network and the EMEP/EEA cold and hot emission factors are employed to estimate related emissions. All the other urban emission sources were considered to contribute to the regional background concentrations and estimated with the WRF-Chem model, which estimates also initial and boundary meteorological conditions (multi-scale approach). The general objective of the inter-comparison is to use equivalent input data for both the models keeping the emissions and the meteorological initial and boundary/condition consistent so that any discrepancies in output would be the results of differences in the micro-scale dispersion models. Since different turbulence parametrisation and dispersion scheme are implemented in the two models, the goal of this study is to identify the strengths and the weaknesses of both the models in reproducing urban NOx concentrations, in a real case application, at urban traffic and urban background sites.

2021 - Urban population exposure forecast system to predict NO2 impact by a building-resolving multi-scale model approach [Articolo su rivista]
Veratti, G.; Bigi, A.; Lupascu, A.; Butler, T. M.; Ghermandi, G.
abstract

Operational forecasting systems based on chemical transport models (CTMs) nowadays generally produce concentration maps with a resolution in the order of 2–5 km, very rarely exceeding the sub-kilometre scale. The main reason for this restriction is the prohibitive computing cost that a simulation covering an entire country would have if set-up with a resolution in the order of meters. In this paper a hybrid forecast system, relying on the WRF-Chem model coupled with the PMSS Lagrangian modelling suite, has been developed and applied for each day of February 2019, to predict hourly NO2 and NOx concentrations with a spatial resolution of 4 m, for the urban area of Modena (a city located in the central Po Valley). Simulated meteorological fields (temperature, wind speed and direction) were assessed at three urban stations, compliant with WMO standards, and modelled concentrations were compared with measurements at two urban air quality stations located at background and traffic sites. Results show that meteorological variables are well captured by the hybrid system and statistical performances are in line with the benchmark values suggested by the European Environmental Agency and with similar case studies focusing on the same area. Modelled NO2 and NOx concentrations, notwithstanding a slight underestimation mainly evident at urban traffic stations for NOx, present a large agreement with related observations. The NO2 Model Quality Objective, as defined by Fairmode guidelines, was met for both the urban stations and the other statistical indexes considered in the evaluation fulfilled the acceptance criteria for dispersion modelling in urban environment, for both NO2 and NOx concentrations. In the second section of the study, the population exposure to forecasted NO2 concentrations has been evaluated adopting a generic model of dynamic population activity. The population was distributed at hourly time steps in specific urban micro-environments at the same resolution of the concentration maps (4 m) and the short-term exposure has been computed as the product between the population density in each model cell and related surface NO2 concentrations. An infiltration factor was also applied to estimate indoor concentrations. The hybrid system was shown to be particularly suited for assessing short-term peak exposure in areas influenced by traffic emissions. On the other hand, due to the limited time spent by the population within traffic related environments, the long-term population exposure calculated by the hybrid system tends to be similar to the WRF-Chem stand-alone estimate.

2020 - Estimate of Secondary NO2 Levels at Two Urban Traffic Sites Using Observations and Modelling [Articolo su rivista]
Ghermandi, Grazia; Fabbi, Sara; Veratti, Giorgio; Bigi, Alessandro; Teggi, Sergio
abstract

2020 - The development of a building-resolved air quality forecast system by a multi-scale model approach and its application to Modena Urban area, Italy [Relazione in Atti di Convegno]
Veratti, G.; Bigi, A.; Fabbi, S.; Lupascu, A.; Tinarelli, G.; Teggi, S.; Brusasca, G.; Butler, T. M.; Ghermandi, G.
abstract

One of the main critical air pollutants in terms of health effects is nitrogen dioxide (NO2), whose levels in the last years exceeded national and WHO (World Health Organization) standards in many urban areas across the Po Valley (Northern Italy), exposing urban population to the risk of pollution-related diseases and health conditions. The main goal of this study was to develop a multi-scale modelling system able to forecast hourly NO2 and NOx concentration fields at a building-resolving scale in the urban area of Modena, a city in the middle of the Po Valley, in order to support environmental policies and to take timely protective actions given a forecast of impeding poor air quality. The modelling system relied on two different tools: the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), which is able to compute concentration fields over regional domain by considering specific emission scenarios and the Parallel Micro SWIFT and SPRAY (PMSS) modelling suite accounting for dispersion phenomena within the urban area. PMSS was used to simulate at building-scale resolution the dispersion of NO and primary NO2 produced by urban sources. Conversely, the WRF-Chem model was selected to reproduce the meteorological input for PMSS and to estimate the formation of secondary NO2. Modelled NO2 and NOx concentrations were compared with measurements at two urban stations, one at traffic site and at background location. Notwithstanding a slight underestimation, mainly evident at urban traffic stations for NOx, simulated concentrations present a large agreement with related observations. The NO2 Model Quality Objective, as defined by Fairmode guidelines, was met for both the urban stations and the other statistical indexes considered in the evaluation fulfilled the acceptance criteria for dispersion modelling in urban environment, for both NO2 and NOx concentrations. In the second section of the study, the population exposure to forecasted NO2 concentrations has been evaluated adopting a generic model of dynamic population activity. Indoor house micro-environments contributed up to 67 % of the total exposure, whilts other outdoor spaces contributed with 24%, divided between traffic environments (8 %) and other outdoor spaces (16 %). Work related buildings contributed for the ramaining share (9 %).

2020 - Towards the coupling of a chemical transport model with a micro-scale Lagrangian modelling system for evaluation of urban NOx levels in a European hotspot [Articolo su rivista]
Veratti, Giorgio; Fabbi, Sara; Bigi, Alessandro; Lupascu, Aurelia; Tinarelli, Gianni; Teggi, Sergio; Brusasca, Giuseppe; Butler, Tim M.; Ghermandi, Grazia
abstract

2019 - A multiscale modelling approach for evaluation of urban air quality in Modena (Italy) [Relazione in Atti di Convegno]
Veratti, G.; Fabbi, S.; Bigi, A.; Lupascu, A.; Tinarelli, G.; Teggi, S.; Brusasca, G.; Butler, T. M.; Ghermandi, G.
abstract

A multi-scale modelling system was developed to provide hourly NOx concentrations field at building resolving scale in the urban area of Modena. The WRF-Chem model was employed with aim of reproducing local background concentrations taking into account meteorological and chemical transformation at regional scale, conversely the PMSS modelling system was applied to simulate 3D air pollutant dispersion with a very high-resolution (4 m) on a 6 km x 6 km domain. Modelled NOx concentrations reproduced by this modelling system show a good agreement with observation at both traffic and background urban stations.

2019 - Compression ratios comparison between engines operating with producer gas [Relazione in Atti di Convegno]
Mason, J.; Kaufmann, B.; Tartarini, P.; Puglia, M.; Morselli, N.; Veratti, G.; Bigi, A.
abstract

2019 - Estimate of secondary NO2 levels at an urban traffic site by microscale simulation of traffic emissions [Relazione in Atti di Convegno]
Ghermandi, G.; Fabbi, S.; Veratti, G.; Asaro, S.; Bigi, A.; Teggi, S.
abstract

2019 - Forecast of the impact by local emissions at an urban micro scale by the combination of Lagrangian modelling and low cost sensing technology: The TRAFAIR project [Relazione in Atti di Convegno]
Bigi, A.; Veratti, G.; Fabbi, S.; Po, L.; Ghermandi, G.
abstract

2019 - Impact assessment of vehicular exhaust emissions by microscale simulation using automatic traffic flow measurements [Articolo su rivista]
Ghermandi, Grazia; Fabbi, Sara; Bigi, Alessandro; Veratti, Giorgio; Despini, Francesca; Teggi, Sergio; Barbieri, Carla; Torreggiani, Luca
abstract

In order to assess the impact of traffic on local air quality a microscale simulation of pollutant concentration fields was produced for two busy intersections, in Reggio Emilia and in Modena, Italy. The simulation was performed by the model suite Micro-Swift-Spray, a Lagrangian particle dispersion model accounting for buildings. Direct measurements of traffic flow were continuously collected in Reggio Emilia over the period January 13–24, 2014 by a two channel radar traffic counter and in Modena from October 28 to November 8, 2016 by four single channel radar traffic counters and used for the hourly modulation of vehicular emissions. Combining radar counts with vehicular fleet composition for each municipality, specific emission factors were obtained. For both cities, simulated concentration fields were compared to local air quality measurements at the nearest urban traffic and urban background sites. The simulated NOx showed large correlation with the observations, notwithstanding some underestimation. The results proved the reliability of the procedure and provided a fair estimate of the NO2 mass fraction of total NOx (primary NO2) due to vehicular emissions in the investigated traffic sites.

2017 - Impact assessment of pollutant emissions in the atmosphere from a power plant over a complex terrain [Relazione in Atti di Convegno]
Ghermandi, G.; Fabbi, S.; Arvani, B.; Veratti, G.; Bigi, A.; Teggi, S.
abstract

2017 - Impact Assessment of Pollutant Emissions in the Atmosphere from a Power Plant over a Complex Terrain and under Unsteady Winds [Articolo su rivista]
Ghermandi, Grazia; Fabbi, Sara; Arvani, Barbara; Veratti, Giorgio; Bigi, Alessandro; Teggi, Sergio
abstract

The development of a natural gas-fired tri-generation power plant (520 MW Combined Cycle Gas Turbines + 58 MW Tri-generation) in the Republic of San Marino, a small independent country in Northern Italy, is under assessment. This work investigates the impact of atmospheric emissions of NO x by the plant, under the Italian and European regulatory framework. The impact assessment was performed by the means of the Aria Industry package, including the 3D Lagrangian stochastic particle dispersion model SPRAY, the diagnostic meteorological model SWIFT, and the turbulence model SURFPRO (Aria Technologies, France, and Arianet, Italy). The Republic of San Marino is almost completely mountainous, 10 km west of the Adriatic Sea and affected by land-sea breeze circulation. SPRAY is suitable for simulations under non-homogenous and non-stationary conditions, over a complex topography. The emission scenario included both a worst-case meteorological condition and three 10-day periods representative of typical atmospheric conditions for 2014. The simulated NO x concentrations were compared with the regulatory air quality limits. Notwithstanding the high emission rate, the simulation showed a spatially confined environmental impact, with only a single NO x peak at ground where the plume hits the hillside of the Mount Titano (749 m a.s.l.), 5 km west of the future power plant.

2017 - µ-MO assessing the contribution of NOXtraffic emission to atmospheric pollution in modena by microscale dispersion modelling [Relazione in Atti di Convegno]
Veratti, Giorgio; Fabbi, Sara; Tinarelli, Gianni; Bigi, Alessandro; Teggi, Sergio; Brusasca, Giuseppe; Ghermandi, Grazia
abstract

Based on the air pollutant emission inventory data (INEMAR – Arpa Emilia-Romagna 2010) road traffic in Modena, a city in the central Po valley (Northern Italy), contributes up to the 60% of the total emission in terms of NOx, followed by Domestic Heating (15%) and Industrial Combustion (14%). Goal of the -MO project is to assess the road traffic impact on air quality in the urban area of Modena by a combined experimental and modelling approach. Dispersion of vehicular NOxwas simulated by Parallel Micro Swift Spray (PMSS, Arianet srl, Italy and Aria Technologies, France) over a domain of 6 km x 6 km, including most of the urban areas of Modena, with a horizontal resolution of 4 m. The atmospheric emission sources were estimated by merging local fleet composition data, traffic flux at rush hours simulated by PTV VISUM mobility software and direct measurements collected by radar traffic counters, provided by the Municipality of Modena. The modelling system, implemented on a 16 cores cluster (64 GB of total memory), includes PSWIFT, a parallelized mass-consistent diagnostic wind field model, and PSPRAY, a three-dimensional parallel lagrangian particle dispersion model, both able to take into account obstacles (buildings). A run of the system on an entire day has been performed and is presented. In the next step of the work, NOxatmospheric concentration measurements will be provided by the two urban air quality monitoring sites and by a set of 10 monitoring boxes distributed over the domain and featured by small sensors for NO, NO2and particulates. Among the final goals of the -MO project there is the tentative source-apportionment of urban atmospheric NOxbetween traffic emissions, domestic heating and regional background, to support epidemiological studies and finally future urban development strategies.

2017 - Vehicular exhaust impact simulated at microscale from traffic flow automatic surveys and emission factor evaluation [Relazione in Atti di Convegno]
Ghermandi, Grazia; Fabbi, Sara; Baranzoni, Giulia; Veratti, Giorgio; Bigi, Alessandro; Teggi, Sergio; Barbieri, Carla; Torreggiani, Luca
abstract

Vehicular emissions are a large NOx and CO source in Italian urban areas. In order to assess the impact of heavy traffic roads on local air quality a micro-scale simulation of pollutant concentration fields was produced. The investigated areas are in downtown of Reggio Emilia and Modena, two cities in central Po valley, Italy, and focused on high traffic intersections. An urban traffic station of the regional air quality monitoring network is present in both investigated areas, where traffic is expected to be the main local source of atmospheric pollutants. The simulation has been performed by the micro-scale model suite Micro-Swift-Spray (Aria Technologies, France and ARIANET, Italy) a Lagrangian particle dispersion model directly derived from the SPRAY code, able to account for buildings and obstacles. Simulated pollutants are NOx and CO, as main tracers of combustion emissions. Direct measurements of traffic flow have been continuously collected for 12 day survey periods (in Reggio Emilia from January 13 to 24, 2014 by a two channel doppler radar traffic counter and in Modena from October 28 to November 8, 2016 by four one channel doppler radar traffic counters) and used for the hourly modulation of vehicular emissions. Specific emission factors were obtained by the combination of radar counts with vehicular fleet composition for each municipality: these depend on vehicle type, fuel type, speed and EURO category and were calculated according to the EMEP/EEA guidelines for air pollutant emission inventory. Simulated concentration fields were evaluated over the period with direct traffic counts for the two studied areas: for both areas the results were compared to local air quality measurements collected at the traffic urban monitoring stations and also at the respective urban background stations. The simulated NOx hourly concentrations show a very large agreement with the observations, even if they result underestimated compared to the observed atmospheric concentrations at the traffic site. Simulated and observed concentrations show a fair agreement for CO. The results outline the representativeness of air quality stations in characterizing the sites for pollution level and for dominant pollutant sources.