Inter-disciplinary assessment of greenspace health benefits applying the ecosystem services framework to urban heat reduction in Boston, MA

Abstract

Background Vegetation is an indispensable component in cities for mitigation of negative health effects of urban exposures such as polluted air and urban heat islands. While there is epidemiology evidence showing urban vegetation exposure is associated with health benefits, knowledge on the underlying causal pathways is limited. We leveraged the ecosystem services framework (ESF) to bridge inter-disciplinary gaps between ecology and public health, and linked evapotranspiration produced by urban vegetation to heat-related exposure risks in Boston, MA.Methods ESF conceptualizes the benefits of nature as an outcome of supply and demand of services provided by ecosystems (ESS). We modeled hourly latent heat flux of tree canopy in Boston as the supply of heat reduction provided by ecosystems at 30 meter resolution. We mapped demand by calculating a risk score as a function of population, ambient temperature, and population vulnerability across multiple sociodemographic dimensions. Comparing the two products revealed to what extent the heat-reducing capacity of urban vegetation meets demand for this service by Boston residents.Results Our results generated fine scale metrics to quantify urban vegetation supply and demand in the context of heat exposure, and revealed spatial patterns of mismatch across Boston. Many areas where risk of heat-related health impacts was high received relatively low protection from extreme heat from surrounding trees, and these hotspots appeared mainly around large affordable housing complexes.Conclusions By applying an interdisciplinary ecosystem services framework, we generated a fine scale greenspace metric that reflects its direct impact on heat reduction. This novel metric can be used in environmental epidemiology studies across a range of heat related health outcomes, improving greenspace exposure assessment, and potentially advance analyses towards a causal pathway between urban vegetation and health.