Green Cities, Healthier Children: The Effect of Expanding Urban Green Space on Body Weight for Primary School Starters.

The discussion on tackling childhood obesity is often centered around fostering physical activity. A potential relationship yet overlooked could run from providing the proper environment for healthy lifestyles to reduced weight problems. A unique quasi-experimental setting of transforming former airport grounds to a large urban green space allows me to apply a difference-in-differences approach within an intention-to-treat framework, comparing several weight outcomes of residential children to children living further away before and after park opening. I use new administrative data on the Berlin district level from mandatory school entrance examinations and provide robust evidence of a lower probability by 4.3% points for treated children to be overweight (BMI > 90 P.), driven entirely by girls, mainly by children from foreign cultural backgrounds and children with less childcare exposure. My results are robust to corrective methods of inference, including synthetic controls, and may open a new perspective for obesity policy action and prevention.