INTRODUCTION
From 2021 all Euro 5 and Euro 6 automobiles with endothermic engines (diesel, petrol, LPG and methane etc.) currently on sale in European Union countries will have sophisticated filtering systems and technologies aimed at eliminating the most harmful polluting compounds contained in the exhaust gases. The series of modern anti-pollution devices with which endothermic engines are fitted, plus the ever-stricter EU regulations on limiting harmful and climate-altering emissions, together with a new collective environmental awareness are, in any case, leading the automobile market towards complete decarbonization (in the medium-term, expected to be between 5 and 10 years). The current tendency is clearly towards zero-emission, completely electric BEV-type vehicles.
Means of transport in general cannot be considered as the only source of air pollution. Nevertheless, particularly in residential centres with a lot of traffic and congestion, the obsolescence of the vehicles, especially diesel, of pre-Euro 4 standard registered up to 2010, produce considerable emissions, especially the dangerous PM 10 and PM 2.5 particles.
Especially in the city, the concentration of old-generation vehicles on the road and the quantity of people that live and work there, means that, today, there is great concern about public health and therefore attention is increasingly being focused on the use of electric, zero-emission vehicles, whether private cars or public transport to avoid the emission of polluting and climate-altering gas emissions, but also irritating noise pollution that affects people’s quality of life.
THE CONSEQUENCES OF AIR POLLUTION
In a single year there are 52,300 premature deaths in Italy associated with exposure to fine particles (PM 2.5). There’s a war going on! The European Environmental Agency’s figures are clear: many Italian cities are still suffering from harmful pollution, which shortens life expectancy, provoking premature death and very serious diseases. The two Italian cities at the top of the table for premature deaths linked to pollution are Brescia and Bergamo, but also Vicenza, Saronno and Verona are among the first eleven in the whole of Europe.
As further examples, let’s take the two cities closest to home: Modena and Reggio Emilia. The scenario is worrying: deaths per year number respectively 139 and 115, numbers that could be avoided if the PM 2.5 levels respected the air health limits.
The Italian cities where nitrogen dioxide and relative NOx pollution is most present are Turin (the absolute third in Europe, with 34 deaths per year) and the Milan metropolitan area, which grieves as many as 103 deaths per year. Modena is at 79th place, Reggio Emilia at 77th (there don’t seem to be direct deaths recorded caused by excesses of NO2 gas; nevertheless, there are around 110 people in Modena and 77 people in Reggio Emilia who would not be dead, every year, if the level of NO2 was the same as the least polluted European city, Reykjavik, in Iceland!).
Origin of the particles
The origin of PM 2.5 and PM 10 particles can be natural: the particles expelled during volcanic eruptions, the products of burning wood during fires, and vegetable pollens dispersed in the air during spring, for example. The natural causes are not, however, cause for concern: concern for people’s health relates to the particles provoked by the use of fossil fuels for automotive transport and heating. Electrification will, therefore, be increasingly necessary for mobility and for the air-conditioning of city buildings, together with improvements in energy efficiency, in order to reduce polluting gas emissions to a maximum and also, to a certain extent, also climate-altering emissions.
Health hazard of particle pollution
The IARC (International Agency for Research on Cancer) has put all substances constituting atmospheric pollutants in Group 1 of its classification together with the worst carcinogenic agents in circulation. The fine PM 2.5 particle, in particular, is dangerous because it penetrates the human organism through the respiratory system: the smaller the dimension of the particle, the easier is access into the organism, arriving at the bronchi and alveoli with regards to the finest particle, smaller, therefore, than 2.5 µm. The impact of the particles on human health is seen in a greater occurrence of tumours, especially those of the lungs, but also of the colon and the intestine.
Health hazard of nitrogen dioxide, NO2
Nitrogen dioxide, NO2, is a typical air pollutant, originating principally from road traffic. Diesel and LPG engines emit more NO2 than petrol engines. NO2 has a pungent small and can cause eye, nose or throat irritation and therefore also coughing. Harmful alterations of the respiratory functions can occur in sensitive people, such as children, asthmatics or people suffering from chronic bronchitis. In Euro 5 and Euro 6 diesel engines there’s a considerable reduction in NO2 thanks to technological exhaust gas treatment devices, such as EGR, Exhaust Gas Recirculation, but the total elimination of pollutants is still today very difficult and problematic!
CONCLUSIONS
All vehicles with diesel engines, due to the limits linked to their nature in relation to practical, dynamic driving contexts, especially urban ones, characterised by sudden and variable accelerations, have high NO2 emissions, albeit limited by technical gas treatment devices.
Other types of ICE engines, such as petrol engines, have high CO2 emissions deriving from inefficiency in the combustion cycle. Furthermore, noise emissions, harmful to the health, especially in cities, are not to be ignored.
Emissions of PM 2.5 and PM 10 particles have been significantly limited with the Euro 5 and Euro 6 standards, by anti-particle filters (FAP), which filter the particle pollutant when the car moves around in the city, and eliminates it, at high temperatures, at higher speeds.
Electric vehicles, therefore, besides the journey comfort and the absence of noise emissions, are to be considered, thanks to the zero emission of gases, as the future of future city mobility, but it is hoped that they can also be the solution for public transport and last mile logistics.
GLOSSARY
BEV – a completely battery-operated electric vehicle (BEV = Battery Electric Vehicle).
PM 2.5 – the acronym that means Particulate Matter ≤ 2.5 µm, is the particulate matter dispersed in the air, the series of solid and liquid atmospheric particles suspended in the air. The term PM2.5 identifies the particles of an aerodynamic diameter less than or equal to 2.5 µm, a fraction of the aerodynamic dimensions of the PM10 and contained in it.
PM 10 – the acronym that means Particulate Matter ≤ 10 µm, is the particulate matter dispersed in the air, the series of solid and liquid atmospheric particles suspended in the air. The term PM 10 identifies the particles of an aerodynamic diameter less than or equal to 10 µm.
NOx – identifies generically the nitrogen oxides NO, NO2, NO3, … which are emitted as sub-products during combustion.
ICE – Internal Combustion Engine.
Climate-altering gases – gases that cause the greenhouse gas effect, that is, climate warming and alteration.