1.) l think the air is polluted.
If the air pollution increases it will be difficult to breath and people will get ill more often and die earlier.
2.) l think the our health is in danger.
If our health is in dange we will take care of it more thoroughly.
3) I think the you'll kill fish.
If you kill fish we will have nothing to eat soon.
4) I think the you'll destroy the land and sea world.
If you destroy the land and sea world we will have to leave our planet and go to Mars, for example.