In a press release to Lusa, the company said that 13,516 seats will be covered with cork, a product of national origin, lower cost, easier to maintain and environmentally friendly, coinciding with the "2020 - Lisbon Green Capital of the European Union" initiative.

"The new material for the seats and seat backs, which will replace the current fabric, is made of a cork composite, its texture and natural colour being more perceptible," the carrier said.

According to the statement, since 2013 the metro has around 200 cork lined seats on an experimental basis, which are in good condition.

The replacement of the seats linings began on Monday, and, on average, one to two units per week (a six-car train) should be completed.

According to the company, the expected durability of the new cork-lined seats is estimated at 15 years, which is longer than the fabric lining.

The seats and backs have been dimensioned for total resistance in their daily use and, due to the properties of the chosen materials, are easy to clean and meet the requirements for the emission of fumes and toxic gases.

Metro de Lisboa foresees that the replacing will last throughout the year 2020.