Here we have a lovely house. Bob live there. He is complaining about the environment.
But, Bob is TOO FREAKIN' STUPID (sorry) to know that there is nothing wrong where he lives.
It is the same thing with noise, it's all green. Another case of Bob being clueless.
As long as they sense a noise/pollution/radioactive tile can reach them and the trees only protect them (maybe), their environmental happiness lowers. As the disgusting tiles get closer, their happiness decrease.