Step-by-step explanation:
1. Constant exposure to noise pollution will lead to the loss of hearing.
2. Because we had turned on so many light bulbs, our eyes were strained.
(Eliminate "of", conform to past tense.)
3. If he read this article, he wouldn't do any more harm to the environment.
4. The local citizens would be very happy if they were supplied with clean water.
(Remove "a")
5. If the environment were polluted, birds wouldn't leave their habitats and plants would die.