This is a fairly recent picture of Central Park.
When I was a child, I read a book called Tales of a Fourth Grade Nothing by Judy Blume. In the book, the main character talks about how they live near Central Park and how because of pollution, the leaves on the trees just turn brown and drop off instead of turning colors like he saw once on a family trip.
The book came out in 1972.
So, yes.... Problems that were such background noise in our lives that it was a throwaway line in a children's book can and have been solved.
(Yes, I know. Blume almost certainly wanted to draw attention to it to help people see the value in environmental regulations)
