Pollution in cities is pretty much an accepted thing, but what about pollution in the country?
This may come as a surprise to you, but big city pollution actually affects trees in the country.
According to a study conducted by Jillian Gregg, who now works at the EPA's western-ecology division in Oregon, Eastern Cottonwood trees grew twice as big inside the Bronx as they did growing in small towns on Long Island.
Cities are full of pollution, and it does have a detrimental effect on plant life--to say nothing of people life! But that doesn't mean, unfortunately, that the converse is true --that once you get outside of the city, the environment is clean.
Some regions can suffer from pollution that blows in from the cities and then lingers around the countryside. In particular, ozone does this.
Gregg's study, along with others, are fingering ozone as the factor that most significantly affects plant growth. Cities make the pollution but it blows over the countryside and hurts trees there instead.
It's just another warning about the surprising effects of pollution--and how we all suffer from it, even when we think it's someone else's problem.