Denser urban tree canopy is touted as an effective summertime preventive health measure in the findings of a newly released quantitative health impact study. Researchers from the Institute of Global Health in Barcelona led the study — published in the health research and news journal, the Lancet — which estimates how the presence of more trees could affect heat-related deaths.

Combing through mortality data for adults aged 20 or older in 93 European cities between June 1 and August 31, 2015, they attributed 6,700 premature deaths to urban heat island factors. Applying various climatic and geospatial data and modelling, researchers calculated heat intensification within these urban nodes drove temperatures up by an average of 1.5 degrees Celsius, with the highest contribution to premature mortality occurring in southern and eastern Europe. Heat-related causes were deemed responsible for 4.3 per cent of all adult deaths across the total area studied.

Next, researchers modelled the scenario of 30 per cent tree coverage in the urban study areas and determined that could reduce average temperatures by 0.4 degrees C. In the study timeframe, it was estimated that could have prevented 2,644 deaths, equating to 39 per cent of premature heat-related deaths and 1.8 per cent of all adult deaths.

“Our results showed the deleterious effects of UHIs (urban heat islands) on mortality and highlighted the health benefits of increasing tree coverage to cool urban environments, which would also result in more sustainable and climate-resilient cities,” the researchers state in a summary of their work.

“Multiple uncertainties mean that the results could overestimate or underestimate the effectiveness of increasing urban tree coverage in the prevention of heat-related mortality. However, the extent of validation provides sufficient assurance to start incorporating these results into city planning, even as additional research generates more precise local estimates,” the Lancet’s reviewers, from the Center of Health and Global Environment at University of Washington and the Melbourne School of Population and Global Health, maintain. “This fine-scale mapping provides opportunities for cities to identify where interventions are urgently needed to protect the most vulnerable as soaring temperatures continue to be felt globally.”