> Evidently this isn't the case even in Europe and even less likely elsewhere, where smelly diesel engines, motorcycles and garbage have a significant odor prob

> Evidently this isn't the case even in Europe and even less likely elsewhere, where smelly diesel engines, motorcycles and garbage have a significant odor problem. I haven't experienced almost any problem with smelly streets while walking or biking in Stockholm, Oslo, Copenhagen, Helsinki, Munich, Cologne, Amsterdam, Rotterdam, Barcelona, Lisbon, Prague, and the list goes on. The worst I can think of is some smelly alley or higher traffic road in Berlin, or when I was in Milan when garbage collectors were on strike. The worst cities I've ever smelled were São Paulo, Los Angeles, NYC, and San Francisco. Guess what these cities have lots and lots of? Cars.