I remember a conversation I had with a woman that grew up with lead pipes. She acknowledged that it had affected her and others she knew mentally. Nothing they could have really done about it though. Just like all the lead paint we had, and the asbestos ceilings.
I remember driving down to Los Angeles for my first time in 1972 and seeing the dirty air for the first time. My new relatives would talk about the beautiful hills above the city, but I could not see them with all the smog. Years later after they had required cleaner auto emissions and going down there to visit and yes, there are hills above the city. Who would have known.
In the Seattle we would pass through Tacoma on the way to the Ocean. The aroma of Tacoma is what we called it. They improved that too.
Lake Washington in the 50's was so polluted that families weren't letting their kids swim in it. In the 30's may parents lived on the lake and used to pump their drinking water from the lake. In just that short of time the lake went from clear to murky. We used to swim every day in the Summer and it was great for tag, swim a few feet down and nobody could see you.
In the 60's they had Metro which included installing new sewer lines and waste treatment. The lake got cleaned up and now newcomers would never guess how bad it had been.