COPENHAGEN — Jens Danstrup, a 77-year-old retired architect, used to bike all around town. But years of smoking have weakened his lungs, and these days he finds it difficult to walk down his front steps and hail a taxi for a doctor’s appointment. (By Sindya N. Bhanoo)

A version of this article appeared in print on January 12, 2010, on page D5 of the National edition.