The environment - worse, or better?

[kellychaos]

Is pollution cumulative? What I mean to say is that, even if we have the best pollution controls in place, are we battling pollution that has taken centuries to produce so that, in essence, we're only fighting the pollution that we're making today? Are running in place, or are our cleaning efforts actually taking a bite out of past pollution? I know some of this depends on the pollutants involved but I guess I'm thinking in general terms.