1. Each Member State shall establish at least one monitoring supersite per 10 million inhabitants at an urban background location. Member States that have fewer than 10 million inhabitants shall establish at least one monitoring supersite at an urban background location.
Member States whose territory is more than 10 000 km2, but not more than 100 000 km2, shall establish at least one monitoring supersite at a rural background location. Each Member State whose territory is more than 100 000 km2 shall establish at least one monitoring supersite per 100 000 km2 at a rural background location.