Every morning I see the cars in my city, Athens, full of dust, even though almost all land is covered with asphalt or cement. When I asked my parents whether this always happened, they told me that they first noticed it around the period of the Olympic Games of 2004 in Athens. At first they thought it was because of works, dust, etc. But then, they realized that this would be a permanent problem in our city.

The Particulate Matters (PM) are emitted to the atmosphere (primary PM) and formed in the atmosphere (secondary PM). Primary PMs is the one emitted by natural pollution, such as the dust that comes from the Sahara desert, sea salt etc., but also emitted by anthropogenic factors, such as automobile exhaust, Powerplant industries, especially those that work with carbon. Carbon has been the most important fuel in Greece, because of its modest cost, and despite the considerable efforts made in the last 15 years to switch to alternative energy sources. Secondary PMs are formed by chemical reactions in the atmosphere. The main chemical reactants are SO2, NOx and NH3 which create ammonium, sulphate and nitrate compounds. These chemical reactions create new PM or condense onto existing and create the so-called secondary inorganic aerosols.

The Ozone at ground level (tropospheric) which is an important pollutant is also generated by complex chemical reactions in which Nitrogen Oxides play a large role. The largest producer of Nitrogen oxides in Europe is transport. Indicatively, in 2013 it contributed at 46$ of the total NO2 emissions.

In Europe from 2004 to 2013 there is a reduction of pollutant emissions. In particular, PM 10 and PM25 were reduced by approximately 15% (Figure 1). At the same time decreased and the air content of toxic metals such as As, Cd, Ni, Pb, Hg, etc. (Figure 2). This was mainly a consequence of the reduction of pollutants from transport. But in the production and distribution of energy, particularly for PMs a significant reduction was not achieved.

According to EU data (http://www.eea.europa.eu/publications/air-quality-in-europe-2015/at_download/file) Greece's situation is among the less aggravated in Europe (Figure 5).

However, Athens is particularly aggravated in PM 10. Two factors particularly contribute to that. First, the large number of trucks that are badly maintained and burn oil, and second, over 10.000 diesel taxis (which are also usually not well maintained). Note that under Regulation Euro 5 clearance levels of nitrogen oxides (NOx) emissions for diesel is three times compared with the corresponding limits for gasoline.

Unfortunately, the economic crisis in Greece significantly contributes to keeping obsolete and poorly maintained cars, trucks, and taxis, contributing to high levels of PMs.

In my family we agreed to turn our car from petrol running to gas (LPG) running, resulting in a significant reduction in exhaust emissions, but also on the family budget.

Another interesting feature is the announcement of the World Health Organization (WHO) that Air pollution costs European economies US$1.6 trillion a year, in diseases and deaths http://www.euro.who.int/en/media-centre/sections/press-releases/2015/04/air-pollution-costs-european-economies-us$-1.6-trillion-a-year-in-diseases-and-deaths,-new-who-study-says.

I think it is clear to conclude that the protection of the environment and the investments for air pollutant reduction, other than improving the quality of life, they do create a very positive effect in the economy.