One big one is air pollution. It is huge in terms of health affects on the population but we ignore it because of the feeling that it cannot be helped. When we finally clean our air it is going to seem ridiculous that we accepted our faith to live our whole lives in toxic fumes for two whole centuries.
We've already made huge strides in this. Here's [0] a gallery of shots of LA smog in the middle part of the last century. It's full of pictures of people crying because the air pollution is stinging their eyes. It's nearly unthinkable today, aside from the random winter day in Salt Lake where an inversion traps everything. But it was a daily occurrence back then!
