During May 2021 Athens was the 5th most polluted city of Europe concerning Nitrogen Dioxide (NO2).
Levels of NO2 are always very high in our city, way above the safety levels. The concentration of NO2 in the air may not exceed an annual average of 40 μg/m3, according to the EU Air Quality Directive. In Greece the NO2 annual mean exceeds this limit by at least 40%, and in Athens much more than that.
NO2 is a toxic gas known to cause lots of health issues including asthma and other chronic diseases of the respiratory system.
It has a very characteristic smell and red color that we can immediately recognize in the city smog.
NO2 hence comes mainly from energy production, industry and transport (especially from diesel engines). The Nitrogen (N2) and Oxygen (O2) naturally occurring in the air combine at high temperatures to form NO2: N2 + 2 O2 = 2 NO2
NO2 has more than doubled in our cities since 1990 because of the growth of diesel car sales, and is expected to grow more if no measures are taken. In fact, road traffic is responsible for up to 80% of illegal levels of nitrogen dioxide air pollution in cities.