The increased concentration of airborne particulate matter (PM) and nitrogen oxides (NOx) in the atmosphere of many European cities is still a major environmental problem.
Airborne particulate matter (PM) is a complex mixture of microscopic particles derived from natural sources, such as volcanic explosions, dust resuspension and pollen, and anthropogenic sources, such as transportations, combustion processes, processing of mineral and agriculture. They are responsible for various effects on climate, visibility reduction, acid rain and health effects, such as respiratory and heart problems and even cancer.
Nitrogen oxides (NOx, essentially NO2) are compounds formed by reactions between N2 and O2, which is in the air. High temperature is determinant factor in the mechanism of NOx formation, because when there are high levels of temperature, the rate of formation is increased. The major source of NOx is anthropogenic and concerns the transportations and the industrial activities. NOx are responsible for various environmental and health effects, such as formation of ground-level or “bad” ozone which can cause severe respiratory problems, degradation of water quality and global warming.
Therefore, many research teams across Europe have been looking into these matters and have developed calculation models and innovative tools, in order to estimate the level of PMs and NOx in the air. These models and tools are useful not only for emission calculation, but also for decision making concerning the actions and policies which can lead to emissions reduction.
Concerning PM emissions, the ACEPT – AIR project developed a cost efficient policy tool for reduction of PM in air. The project was a joint venture of the Greek National Centre for Scientific Research "Demokritos", University of Thessaly, Aristotle University of Thessaloniki, Technical University of Crete and AXON Envirogroup Ltd. It was funded by the European Commission, within the framework of LIFE programme, and it has been awarded as one of the best LIFE projects for 2015.
The ACEPT – AIR tool has many and useful functionalities. It identifies the pollutant, recognizes the sources of pollution, estimates the contribution of various sources of pollution, assesses the effectiveness of response measures, which have already been applied, compares different emission scenarios of PM and estimates pollutions levels, in order to determine and purpose sustainable measures. The methodology, which was developed and followed for the successful completion of the project, consists of 3 major steps. In the first step, the concentration and chemical speciation of PM10 and PM2.5 in selected sampling sites and the chemical profile of aerosol particles emitted by various sources in the general area are estimated. After that, the second step concerns the application of a Chemical Mass Balance receptor model in order to identify the sources contributing to PM10 and PM2.5 and the quantification of their contribution. In the third step, PM10 and PM2.5 emissions from anthropogenic and natural sources in the areas under study are recorded. All these steps led to the development of the ACEPT – AIR policy tool and the reduction of PM concentrations in the air of urban environments. Additionally, it should be noted, that the tool has been applied in three Greek cities, Athens, Thessaloniki and Volos in order to identify the PM emissions levels and to take the appropriate decisions about the reduction of them.
On the other hand and concerning NOx emissions, a team of researchers from Heidelberg University of Germany led by environmental physicist Dr. Denis Pöhler has developed NO2 ICAD. It is an innovative and easy-to-use mobile device which can measure NO2 in the exhaust of the preceding vehicle.
This spectroscopic instrument delivers reliable emission values under actual driving conditions, measurements that were formerly possible only with expensive systems attached directly to the vehicle. Rather than insufficient model calculations, the data collected via the mobile device can be used to identify major polluters, according to Dr. Pöhler. There have been also accomplished practical tests of NO2 ICAD in the German city of Mainz. The researchers recorded more than 730 vehicles in under real driving conditions. They identified the parts per billion (ppb) of NO2 in the given exhaust plume and compared this value with the so-called background concentration of nitrogen dioxide. This allowed them to draw conclusions about the emissions of the individual vehicles.
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