As our readers know, Milan created a pollution tax system (called EcoPass) to stop highly-polluting cars from driving inside a section of the city center. One month after its introduction, la Reppublica has published a very encouraging article (in Italian) that details all the positive things the measure has brought for the Milanese. The article is very thorough, speaking about lots of indicators, but we'll just highlight the most important ones.
First of all, traffic figures are down by 22.7 percent, or by 26.7 percent if you exclude public transport vehicles (buses and taxis). This had the side benefit of increasing the average speed of the vehicles that do remain by 11.3 percent. The figures for the subway train lines (Metropolitana) went also up, with more people (9.1 percent more) using it to access the city center.
The highest reduction in car usage came from the most polluting cars (those under the Euro I, II and III norms), which have to face higher prices to access the zone: the number of these cars dropped by 40 percent.
Maybe the most remarkable figure is the measurement of the quantity of certain pollutants. Pm10 (particulates under 10 micrograms) were down by 26 percent, NOx was down by 21 percent and ammonia by 40 percent.
Lastly, the Comune (city hall) also got 2.5 million EUR of additional income.
[Source: La Repubblica (h/t to Karl-Uwe for the tip) - Link is in Italian]