Greener cities equal 'healthier hearts'

Green spaces help promote physical activity, reduce stress and mitigate heat and air pollution. (Russell Freeman/AAP PHOTOS) (AAP)

While conventional wisdom says an apple a day keeps the doctor away, more recent health advice suggests 10,000 steps will too.

But what about just a casual stroll in the park? Well, it can, although it depends, curiously enough, on whether people live in houses or flats and what kind of green space they have access to.