"Strengthening of controls on old diesel-powered vehicles, after the introduction of catalyzed filters, and the methanization of domestic heating in place of other fuels played a fundamental role," noted Michele Giugliano, a distinguished professor of atmospheric pollution at Politecnico di Milano University.

The "Area C," or the congestion charge introduced last year, though was not created to affect concentrations, also led to notable lowering by 30-40 percent of pollution markers such as black carbon emissions. Furthermore, it caused a reduction by more than 30 percent of vehicles inside the designated restricted zone and 7 percent outside it, according to official estimates.

Above all, the lowered congestion in the city center resulted in increased average speed and use of public transport, which is a fundamental factor linked to the necessary "culture-oriented approach" to the pollution problem, Giugliano stressed.

"Area C as well as the Car free Sundays have the merit for helping citizens actively realize the need for everybody to do their part in the fight against pollution," he said. But the more than 700,000 vehicles in Milan are still too many for a population of around 1.3 million, the second largest in Italy after capital Rome.

Much more needs to be done, the expert highlighted, in the direction of enhancing clean technologies, in compliance with the European regulations, and public transport with large investments both in Milan and, more importantly, in collaboration with the surrounding districts.

In view of the Expo 2015, Milan has equipped with additional 300 bus routes on 14 lines per day and a reinforced bike share system counting nearly 3,000 bicycles, 40 percent more than in 2012. By spring 2013, the business city will be embellished by 7,300 new trees, Xinhua also learnt from local officers.

Among the latest initiatives, there was a project aimed at promoting a better use and maintenance of tires, whose deterioration contributes to pollution.

On the heating side, Milan has been increasingly implementing "district heating", a system that transfers and distributes heat from one or more heating plants to residential, commercial and industrial consumers. More than 85,000 apartments or a rough figure of 20 million cubic meters, 6.5 percent more than last year, are being treated with district heating.

Furthermore, a new plan for control of environmental standards in heating plants was launched with the objective to reach nearly 13,000 checks a year, 25 percent more compared to 2011, while a series of new "energy desks" are being created across the city to provide information on energy efficiency.

The experts said that one of the next necessary steps would be holding back the use of wood or wooden pallets as a fuel that, though helps greenhouse gas reduction, deepens particulate concentrations. In fact, benzo(a)pyrene levels were generally overcoming the target value in the areas where the use of wood is more widespread.

"There is no miraculous technology to solve the complex threat of pollution," Giugliano said. Coordination and synergy on a large scale between all different players is therefore the decisive ingredient to make every single action effective in the long term, he concluded.