Fiat Punto only euro3 in the future problems?

Hello, my son wants to buy himself a Punto. – He is very enthusiastic about the car. Built 2003 , few km, gasoline, 60 hp. He has but only Euro 3. In Hanover e.g., from 2010 cars with euro 3 can no longer drive to the city center. Can one change the Punto somehow – and if so, what does that cost??? Greeting Dirk