… is from page 515 of Julian Simon’s profound 1996 book, The Ultimate Resource 2  (link added):
The public demands an ever-increasing purity of air and water. In itself that certainly is a good thing. But when the public judges that our air and water now are “dirty” and “polluted,” this makes no sense if one remembers the terrible pollutions that were banished in the past century or so – the typhoid fever that polluted even the Hudson River at New York, the smallpox that humanity has finally pursued to the ends of the Earth and apparently eradicated, the dysentery and cholera that distressed and killed people all over the world as it still does in Asia and Africa, the plagues and other epidemics that harm us much less than in generations past, or not at all. Not only are we in the rich countries free of malaria (largely due to our intensive occupation of the land…), but even the mosquitoes that only cause itches with their bites are now so few in many affluent urban areas that people no longer need window screens  for their homes, and can have garden parties at dusk.
It is a proof of our extraordinary success at healing the Earth that the horrors of the past which were transmitted by filthy air and water are no longer even thought of as pollutions.