Article 4 of the Sofia Protocol states: The Parties shall, as soon as possible and no later than two years after the date of entry into force of the present Protocol, make unleaded fuel sufficiently available, in particular cases as a minimum along main international transit routes, to facilitate the circulation of vehicles equipped with catalytic converters.
One litre of unleaded petrol costs 37 US cents in the United States, but the equivalent of US$ 1.30 in Norway.