Green spaces encourage people to be physically active and reduce stress.

Green spaces like parks and forests help narrow health gaps between the rich and poor living in cities, say researchers who are urging urban planners to invest in greenery.

In Saturday's issue of the Lancet, Richard Mitchell of the University of Glasgow and his colleagues looked at mortality records, income data and the amount of green areas for more than 366,000 people in England who were below retirement age in 2001 to 2005.

In general, studies show that people living in poorer areas tend to be more unhealthy and die earlier because of differences in diet, lifestyle and access to medical care.

Living near open, undeveloped land such as parks, forests, playing fields and river corridors seemed to help reduce this gap, according to the latest study.

The difference in the rate of deaths between the richest and poorest was roughly halved for those living with the most greenery around them, compared with those with the fewest green spaces, the researchers found.

"The size of the difference in the health gap is surprising and represented a much bigger effect than I had been expecting," said Mitchell.

"So the key message is green spaces are another tool for governments to combat this health gap between rich and poor."

Green space `more than pretty'

The difference more than doubled for deaths from circulatory disease such as heart disease and stroke, but there was no effect on suicides, the researchers said.

Green spaces may encourage people to be more physically active, and previous studies have suggested that parks and open space help people reduce blood pressure and stress levels, and perhaps even heal more quickly after surgery.

"The implications of this study are clear: environments that promote good health might be crucial in the fight to reduce health inequalities," the study's authors concluded.

In a commentary accompanying the study, Terry Hartig of the Institute for Housing and Urban Research at Uppsala University in Sweden agreed: "This study offers valuable evidence that green space does more than pretty up the neighbourhood. It appears to have real effects on health inequality, of a kind that politicians and health authorities should take seriously."

The final report of the World Health Organization's Commission on the Social Determinants of Health also called for wide-ranging improvements in daily living conditions.

Restoring environmental supports to mitigate health inequities could help achieve these goals, Hartig said.