Pollution can take many forms.
Air, water, solid waste - most agree that pollution is harmful for people and other life on Earth. But more controversial is how to best prevent it - and clean it up.
The simple two-wheeler, first invented in Germany in 1817, has evolved into a fast, fun and green machine. As bicycles continue to evolve, cities welcome their eco-benefits, while riders appreciate their convenience.
The City of Prague has launched a new campaign to try and get people to think again when buying a 4x4 for driving in the city’s narrow medieval streets. Critics say SUVs are too big to park in an already cramped capital and create far more pollution than smaller cars. So will the message get through to a nation where SUVs are status symbols? Rob Cameron has more from Prague.