Impact of air quality model settings for the evaluation of emission reduction strategies to curb air pollution

For air quality management, while numerical tools are mainly evaluated to assess their performances on absolute concentrations, this study assesses the impact of their settings on the robustness of model responses to emission reduction strategies for the main criteria pollutants. The effect of the spatial resolution and chemistry schemes is investigated. We show that whereas the spatial resolution is not a crucial setting (except for NO2), the chemistry scheme has more impact, particularly when assessing hourly values of the absolute potential of concentrations. The analysis of model responses under the various configurations triggered an analysis of the impact of using online models, like WRF-chem or WRF-CHIMERE, which accounts for the impact of aerosol concentrations on meteorology. This study informs the air quality modeling community on what extent some model settings can affect the expected model responses to emission changes. We suggest to not activate online effects when analyzing the effect of an emission reduction strategy to avoid any confusion in the interpretation of results even if an online simulation should represent better the reality.

Inventory of Commercial Cooking Activities and Emissions in a Typical Urban Area in Greece

The pollutants emitted during meal preparation in restaurants deteriorate the air quality. Thus, it is an environmental issue that needs to be addressed, especially in areas where these activities are densely located. The purpose of this study is to examine the impact on air quality from commercial cooking activities by performing a qualitative and quantitative analysis of the related parameters. The area of interest is located in the southeastern Mediterranean (Greater Athens area in Greece). Due to the lack of the necessary activity information, a survey was conducted. Emissions from the fuel burnt during the cooking procedures were calculated and it was found that, overall, 940.1 tonnes are attributed to commercial cooking activities annually (generated by classical pollutants, heavy metals, particulates and polycyclic aromatic hydrocarbon emissions). Comparing the contribution of different sources to the pollutants emitted, it was found that commercial cooking is responsible for about 0.6%, 0.8% and 1.0% of the total CO, NOx and PM10 values. Cooking organic aerosol (COA) and volatile organic compound (VOC) emissions from grilled meat were also calculated, accounting for 724.9 tonnes and 37.1 tonnes, respectively. Monthly, daily and hourly profiles of the cooking activities were developed and emissions were spatially disaggregated, indicating the city center as the area with higher values. Numerical simulations were performed with the WRF/CAMx modeling system and the results revealed a contribution of about 6% to the total PM10 concentrations in the urban center, where the majority of restaurants are located.

Long-Term Variations of Air Quality Influenced by Surface Ozone in a Coastal Site in India: Association with Synoptic Meteorological Conditions with Model Simulations

Atmospheric ozone (O3) in the surface level plays a central role in determining air quality and atmospheric oxidizing capacity. In this paper, we review our comprehensive results of simultaneous measurements of surface ozone (O3) and its precursor gas (NOx) and weather parameters that were carried out continuously for a span of six years (January 2013–December 2018) at a typical rural coastal site, Kannur (11.9° N, 75.4° E) in South India. Surface O3 concentration reached its maximum during daytime hours and minimum during the night time. The influence of solar radiation and water content on variations of O3 are discussed. A Multi-Layer Perceptron (MLP) artificial neural network technique has been used to understand the effect of atmospheric temperature on the increase in O3 over the past six years. This has been found that temperature has been a major contributor to the increase in O3 levels over the years. The National Centre for Atmospheric Research- Master Mechanism (NCAR-MM) Photochemical box model study was conducted to validate the variations of O3 in different seasons and years, and the results were shown to be in good agreement with observed trends.

Development of a road transport emission inventory for Greece and the Greater Athens Area: effects of important parameters

Traffic is considered one of the major polluting sectors and as a consequence a significant cause for the measured exceedances of ambient air quality limit values mainly in urban areas. The Greater Athens Area (located in Attica), the most populated area in Greece, faces severe air pollution problems due to the combination of high road traffic emissions, complex topography and local meteorological conditions. Even though several efforts were made to construct traffic emission inventories for Greece and Attica, still there is not a spatially and temporally resolved one, based on data from relevant authorities and organisations. The present work aims to estimate road emissions in Greece and Attica based on the top down approach. The programme COPERT 4 was used to calculate the annual total emissions from the road transport sector for the period 2006-2010 and an emission inventory for Greece and Attica was developed with high spatial (6 × 6 km(2) for Greece and 2 × 2 km(2) for Attica) and temporal (1-hour) resolutions. The results revealed that about 40% of national CO₂, CO, VOC and NMVOC values and 30% of NOx and particles are emitted in Attica. The fuel consumption and the subsequent reduction of annual mileage driven in combination with the import of new engine anti-pollution technologies affected CO₂, CO, VOC and NMVOC emissions. The major part of CO (56.53%) and CO₂ (66.15%) emissions was due to passenger cars (2010), while heavy duty vehicles (HDVs) were connected with NOx, PM₂.₅ and PM₁₀ emissions with 51.27%, 43.97% and 38.13% respectively (2010). The fleet composition, the penetration of diesel fuelled cars, the increase of urban average speed and the fleet renewal are among the most effective parameters towards the emission reduction strategies.

Particulate matter pollution over a Mediterranean urban area

The main purpose of this study is to investigate the aerosols' (PM10, PM2.5, and PM1) spatial and temporal distribution in different types of environment in a Mediterranean urban region, the Greater Athens Area based on data from a sampling campaign that took place during the cold and warm period of 2008. The influence of the atmospheric circulation patterns, the possible local transport mechanisms, as well as the differentiation of the PM behaviour from that of the inorganic pollutants (NOx, O3), are analysed and discussed. Furthermore, the Comprehensive Air Quality Model with extensions (CAMx) was applied for selected sampling dates and its results were evaluated against measurements in order to interpret qualitatively the configured picture of the air pollution above the GAA. Analysis of the measurement data show that local sources such as traffic and industry dominate over the prevailing PM loads, especially at the 'hot spot' areas. Moreover, the synoptic circulation patterns associated with calm conditions and southerly flows lead to high particulate pollution levels that also affect the urban background stations. Saharan dust outbreaks appeared to increase the particles' diameter as well as the number of E.U. limit value exceedances within the stations of our network. Without any dependence on the characteristics of the investigated atmosphere, PM1 always constituted the greatest part of the PM2.5 mass while PM10, especially during the Saharan dust episodes, was mainly constituted by the coarse fraction. The numerical modelling approach of the geographical distribution of PM10, PM2.5, NOx and O3 justified the design of the sampling campaign, indicating the need for the systematic and parallel monitoring and modelling of the pollutants' dispersion in order to understand the particulate pollution problem in the GAA and to aid to the formulation of pollution control strategies.

A study on the atmospheric concentrations of primary and secondary air pollutants in the Athens basin performed by DOAS and DIAL measuring techniques

In this work an analysis of continuous Differential Optical Absorption Spectroscopy (DOAS) measurements of primary and secondary air pollutants (SO(2), NO(2) and O(3)) in the Athens basin is performed combined with Differential Absorption Lidar (DIAL) vertical ozone measurements obtained inside the Planetary Boundary Layer (PBL) and the lower free troposphere. The measurements took place during the period May 2005-February 2007, at the National Technical University of Athens Campus (200 m above sea level (asl.), 37.96 °N, 23.78 °E). The SO(2) and NO(2) DOAS measurements showed maximum 1-hour mean values (around 20 μg/m(3) and 74 μg/m(3), respectively) in winter and did not exceed the current European Union (EU) air quality standards (European Council Directive 2008/50/EC), in contrast to ozone, which shows its maximum (around 128 μg/m(3)) in summer and frequently exceeds the EU standard for human health protection (120 μg/m(3)). If the measurements are classified according to the two most frequent flow-patterns of the air masses in the Athens basin (northern-southern circulation), it is observed that in general the atmospheric concentrations of all measured pollutants including ozone are higher when the southern circulation occurs, in comparison to the corresponding values under the northern circulation. The vertical ozone profiles obtained by DIAL were also higher under the southern circulation. During the summer months a mean difference (between the southern-northern circulations) of the order of 15-20 μg/m(3), maximized at the 0.9-1.1 km and 1.7-1.8 km height, was observed within the PBL. It was also observed that the summer surface ozone levels remained relatively high (around 80-110 μg/m(3)) even during strong northerly winds, verifying the high levels of rural surface ozone in the surrounding area reported by previous studies.

Estimating future air-quality due to climate change: the Athens case study

Abstract. The aim of this study is to investigate the development of an empirical-statistical model in order to examine the potential impact of increasing future temperatures on ozone exceedance days in the Greater Athens Area. It is based on the concept that temperature is a capable predictor for the ozone concentrations and that in a future climate change world, the likelihood of ozone pollution episodes may increase.