MILAN - If Italy's fashion capital has a predominant color, it is gray not only because of the blocks of neoclassical stone buildings for which the city is celebrated, but also due to its often-gray sky, which traps pollution.

But Milan now wants to shift its color palette toward green.

The city has ambitious plans to plant 3 million new trees by 2030, a move that experts say could offer relief from the city's muggy, sometimes tropical weather.

Some ad hoc projects have already contributed to environmental improvements. Architect Stefano Boeri's striking Vertical Forest residential towers, completed in 2014 near the Garibaldi train station, aims to improve not only air quality but the quality of life for Milan residents.

Boeri created a small island of greenery in the heart of Milan, his pair of high-rises brimming from every balcony with shrubs and trees that absorb carbon dioxide and PM10 particles, a pollutant with links to respiratory ailments and cancer.

"I think the theme of forestation is one of the big challenges that we have today. It is one of the most effective ways we have to fight climate change, because it is like fighting the enemy on its own field," Boeri said. "It is effective and it is also democratic, because everyone can plant trees."

United Nations climate talks taking place in Poland have urged cities and regions to help achieve the goals of the 2015 Paris agreement on curbing global warming, which include limiting the increase in the planet's temperature to 2 C this century.

Milan officials estimate the program to boost the number of trees by 30 percent in the broader metropolitan area will absorb an additional 5 million tons of carbon dioxide a year - four-fifths of the total produced by Milan - and reduce harmful PM10 small particulates by 3,000 tons over a decade. Significantly, it would also reduce temperatures in the city by 2 C, they say.

Boeri said the current green canopy of the Lombardy region's capital is just 7 percent of the urban area. That's well below northern European cities like Germany's Frankfurt at 21.5 percent or Amsterdam at nearly 21 percent and closer to Paris, which suffers its own pollution problems, at nearly 9 percent, according to the World Economic Forum's Green View Index.

By 2030, Milan hopes to increase that green canopy number to between 17 and 20 percent.

Because the city lies close to the Alps, Milan gets very little wind to clear the pollutants.

"The lack of wind also accentuates the urban heating," said Damiano Di Simine, the scientific coordinator in Lombardy for the environmental group Legambiente. "It means the discomfort from thermic inversions is terrible, because the climate is very stationary. Planting trees will help this."

Associated Press