Cross on the hand is a metaphor, a recognizable symbol of the task that should be done by it�s owner.
Here cross means a mark of obligation to people all over the world which the political leaders must fulfill.
In real life this mark can be scrubbed with ordinary water & soap. In our case the mark has stand straight for 10 years already as a hint that the promise given at the UN Millennium Summit of 2000 can be scrubbed only by real action.
The series of posters include the flag image of every country UN member so it can be used in every region of Europe (& world). The cross is a key visual which can be used in other advertising activities (for example, field marketing, PR, Guerrilla marketing).