1.   Air pollution is our most serious environmental problem.

2.   Air pollution is particularly bad in urban areas.

3.   Because setting varies enormously, since each watercourse possesses its own unique characteristics, pollution is a highly relative notion.

4.   Pollution from cars is the main cause of global warming.

5.   Pollution is a major problem.

6.   Pollutions are rarely dramatic events in themselves, but are often more striking in their consequences.

7.   Preliminary tests showed that pollution was very high in the river.

8.   The pollution was so bad that most of the fish died.

9.   The report explodes the myth that pollution is only a problem for rich countries.