Someone asked me the following useful questions:
- Instead of 'reduce pollution', can we write 'bring down pollution' or 'lessen pollution'?
- Instead of 'reduce the pressure', can we write 'cut down the pressure'?
My answer is no. Although 'bring down', 'lessen' and 'cut down' can be used as synonyms of 'reduce' in some situations, most native speakers wouldn't choose to use them in the contexts above. In other words, 'reduce pollution' is a common collocation, but 'bring down pollution' isn't.