Free market solutions? The free market has only one purpose and that is to make as much money as it possibly can. Negative externalities, like pollution, unless prohibited by law (and thus the voting public) is not a consideration. By making rules on what is and isn't allowed, the free market has some guidelines that all players have to follow.
Yes, with some (enforceable) guidelines free markets can do better, but that is not a given. I would not want private ownership of roads, nor would I want governments to build the cars to drive on them.