According to a study in the journal Urban Forestry & Urban Greening, the factors that most influence and increase the risk of tree failure in São Paulo (the capital of São Paulo state in Brazil) are the height of nearby buildings and the age of the neighborhood. Sidewalk width and tree height are the next most significant variables. Tree failure in streets with buildings of five or more stories is double the average for the city as a whole, the researchers found. It is also above average in districts created more than four decades ago. It is highest for trees taller than 9.58 m and planted on sloping sidewalks. Newer neighborhoods with lower buildings have 37% fewer cases.