I traveled in East Germany, Hungary, Czechoslovakia, as well as Western Europe, in the 1980s. Visited Leipzig in 1986. Also visited Beijing in 2015 on the worst

I traveled in East Germany, Hungary, Czechoslovakia, as well as Western Europe, in the 1980s. Visited Leipzig in 1986. Also visited Beijing in 2015 on the worst air-quality week of that year. Leipzig was by far the most polluted place I have ever been. It's wonderful to see its transformation. I hope to see it in person again some day. (Pittsburgh and Bethlehem, in my native Pennsylvania, as well as major cities like Philadelphia and NYC, are all far cleaner and nicer today than in the 1980s. NYC is dramatically cleaner than it was as recently as 1999.)