Greener cities equal 'healthier hearts'

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.

According to new Australian research, a healthier heart is more likely for residents of free-standing homes, rather than apartments, especially if they're surrounded by or at least close to tree canopy instead of open expanses of grass.

The findings are based on an analysis of the living arrangements of 100,000 urban-dwelling Australians and their local neighborhoods, along with 10 years worth of hospital and health data.

Studies have previously linked parks and community spaces to helping to reduce heart disease by promoting physical activity, reducing stress and mitigating excess heat and air pollution, lead researcher Professor Xiaoqi Feng from the University of NSW notes.

But there's little understanding of which types of green areas are most important.

"We found people living in houses are more likely to benefit from living closer to trees and tree canopies - for their heart in particular," she said.

"This could reduce the risk of developing heart attack and heart disease-related mortality."

Prof Feng and co-author Prof Thomas Astell-Burt from the University of Wollongong believe this is most likely due to the shade trees cast, which make streets and parks more inviting places to spend time in.

Yet the same cardiovascular benefits aren't necessarily as evident for unit dwellers.

"One reason is apartments are normally quite dense and maybe even crowded," Prof Feng said.

"So you can imagine that if you plant the same number of trees in a low-density area and then a high-density area, the ratio of trees to people changes.

"Also, even if there is some green space within or around your apartment block, it's often not an area you can or would want to visit, or permit children can play in. It's there to tick a box but offers few qualities to attract people to spend time there."

Elsewhere, Prof Feng's work informed a $377 million City of Sydney million strategy to plant 700 new trees annually for 10 years and reach 40 per cent green cover by 2050.

"This research is important for Australia, with the massive urbanisation we can see in Sydney and Melbourne, and worldwide," she said.

"We should learn more about what type and quality of green space we should have around every apartment block, to ensure everyone has an opportunity to benefit from nature."

When cities replace natural cover with dense concentrations of concrete and steel, urban heat islands occur, she said.

According to census data, about 7.5 million Australians live in detached houses - almost three times the combined number of those who reside in medium and high-density dwellings.

The study findings were published in the journal Heart, Lung and Circulation earlier this week. The authors are the founding co-directors of the Population Wellbeing and Environment Research Lab.