From what I remember, NASA wants to use satellites to direct light from the Sun directly on to polar ice caps on Mars and eventually have fungi grow in the water (pond scum, etc.) to produce oxygen and whatnot. Of course, this plan could have changed since this is what I remember hearing maybe 5-6 years ago. The thing is, pollution couldnt be used on Mars anyway. Mars doesnt have a magnetosphere so solar winds would be able to erode the atmosphere of greenhouse gases. One possible workaround would be to pump out more greenhouse gases than the winds take away. Problem is, volcanoes would probably be the only way to outpace the solar winds (since this is on a global scale). Unless it becomes possible to artificially erupt volcanoes (like Olympus Mons), it is going to be very hard to produce a livable atmosphere for Mars (unless people dont mind living on a planet that averages 55 C below zero ).