One fascinating paper shows that crime rates are also strongly affected by vegetation. In housing projects in Chicago with equal levels of poverty, taking account of factors such as size of buildings and vacancy rates, there's a clear association between the absence of greenery and both property crime and violent crime.

Another set of studies demonstrates a relationship between urban planning and body mass index. Where settlements are dense – and therefore able to support public transport – and close to shops, workplaces and recreation places, people are more likely to walk and cycle and less likely to be fat. One paper shows that women living in mixed places, where houses and amenities are close together, have a risk of coronary heart disease 20% lower than women living in areas which contain only houses. Suburban sprawl is partly to blame for obesity. (The references for all these papers are on my website).

Build loose suburbs carved up by busy roads and without green spaces and you help to create a population of fat, lonely people plagued by criminals. Build dense, leafy settlements with mixed uses, protected from traffic, and you help to create safe, fit and friendly communities.

This is a great opinion piece on how urban planning affects our lives. It reminds me of one of the patterns in Alexander's "A Pattern Language" book: City - Country Fingers, talking of the need for green space in urban environments.

Hmm, where to live? Where to live?