Less traffic means less pollution.

减少交通流量就会减少空气污染。

It would be good to have less pollution.

如果污染更少的话就好了。

There will be less pollution in the future.

将来会有更少的污染。

In the future, there will be less pollution.

未来世界，污染会更少。

One less car on the road means less pollution.

马路上车少也意味着污染更少。