you will reduce pollution there
While technically true, will it make any difference? How much heavy metals (e.g. in mcg) would one plant accumulate? How many plants will it take to reduce the heavy metal pollution of a patch of ground by, say, half?
There are too many qualificators to go into detail here. You might wish to choose a plant that takes out more of a specific pollutant, or of several. Here are some references for Conyza canadensis specifically, they will give you the general idea why people are interested in this on industrial scale.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.