B. harmful breathing pollution motorbikes need clean 1. People need to breathe. If they dont breathe, they will die. But how (23) ___________________ is the air people 2. breathe? If they breathe dirty air, they will have (24) _________________________ problems. Plants and animals 3. (25) ____________________ clean air too. A lot of the things in our lives create (26) ______________________ 4. gases and make the air dirty, like cars, (27) ___________________ and factories. Dirty air is called polluted air. 5. Air (28) ______________________________ can also make our Earth warmer.