Basically, the directive defines maximum pollution levels and a timeframe for its implementation. Which type of pollutants? A lot of them, but the focus has been set on microparticulates PM 2.5, which are considered dangerous for human health as they cause respiratory problems. However, these particulates don't come only from diesel vehicles tailpipes. Phenomena such as volcanic eruptions can release a huge amount of them into the atmosphere.
The directive's dates are as follows:
- 2010: a recommended value of 25 µg/m³ of PM 2.5 particules.
- 2015: for this level to be mandatory and a recommended value for 2020 of 20 µg/m³ of PM 2.5 in the air. These levels can only be surpassed 35 times per year, which is something very hard to meet for industrial regions such as the north of Italy.
[Source: Legislation via Moteur Nature]