How much pollution crosses national borders?

Air and water move across national borders, while many environmental decisions are made within them. A river can connect communities that have different priorities and very different resources.

Can environmental protection work well if countries approach shared problems separately?

Neighbours do not always have the same resources, laws or priorities. Sharing measurements can help them understand a common problem, but cooperation also needs clear responsibilities and a way to resolve disagreements. We are interested in examples that have worked, including cooperation between towns or river-basin organisations. A useful discussion can begin with one shared waterway rather than a demand that everyone agrees on everything.

• What crosses a border near you? • Which information should be shared? • Who should coordinate the response?