It would give nature a place to fight back, and become more healthy, and less hindered. Cities mess up the evaporation cycle, and because of parks, the water is able to be soaked up by grass, and then released through evaporation. When it rains over a city, the water goes into gutters, and becomes more polluted.
It seems to have choices. The exposure mutagens may lead to the mutation. When the mutation add up to a certain amount and can lead to cancer. So exposure mutagens will increase the cancer risk.
