[Beatrix]

those two examples are offered in Headway Upper-Intermediate and only 'to pollute' is accepted as the correct one. But why can't we use 'contaminate' as well? don't they have nearly the same meaning? thanks.

[susan53]

You can say it - just try Googling it. But it has a slightly different meaning. Contaminate is likely to be used when there is a specific substance or case involved - I found for example : Oil spills can contaminate indoor air and Carpets and soft vinyl floor coverings can contribute to the levels of VOCs that can contaminate your indoor air.
Pollute can be more general - just a load of unspecified muck that we breathe in every day with long-term rather than short term effects and which no-one takes specific responsibility for. But I think contaminate would be used when the degree of damage was higher and either intentional or due to a specific case of negligence - eg a nuclear explosion would contaminate the air, not pollute it. This can of course be subjective - if I were a motorist I might just shrug my shoulders and accept that traffic fumes pollute the air. As a cyclist I feel strongly that motorists contaminate it!

[Beatrix]

thanks susan!