Increasing Green Infrastructure in Cities: Impact on Ambient Temperature, Air Quality and Heat-Related Mortality and Morbidity

Abstract

Urban vegetation provides undeniable benefits to urban climate, health, thermal comfort and environmental quality of cities and represents one of the most considered urban heat mitigation measures. Despite the plethora of available scientific information, very little is known about the holistic and global impact of a potential increase of urban green infrastructure (GI) on urban climate, environmental quality and health, and their synergies and trade-offs. There is a need to evaluate globally the extent to which additional GI provides benefits and quantify the problems arising from the deployment of additional greenery in cities which are usually overlooked or neglected. The present paper has reviewed and analysed 55 fully evaluated scenarios and case studies investigating the impact of additional GI on urban temperature, air pollution and health for 39 cities. Statistically significant correlations between the percentage increase of the urban GI and the peak daily and night ambient temperatures are obtained. The average maximum peak daily and night-time temperature drop may not exceed 1.8 and 2.3 °C respectively, even for a maximum GI fraction. In parallel, a statistically significant correlation between the peak daily temperature decrease caused by higher GI fractions and heat-related mortality is found. When the peak daily temperature drops by 0.1 °C, then the percentage of heat-related mortality decreases on average by 3.0% The impact of additional urban GI on the concentration of urban pollutants is analysed, and the main parameters contributing to decrease or increase of the pollutants’ concentration are presented.

Growing Biodiverse Urban Futures: Renaturalization and Rewilding as Strategies to Strengthen Urban Resilience

“…In addition, NBS help to keep cities cool, reduce the heat load, bind dust, and manage stormwater, runoff, support the healthy city agenda, and deliver positive impacts from ecosystem services provided by nature within the city. Researchers are working to identify the most impactful principles for the integration of NBS at the urban planning level (e.g., using sustainable drainage systems and bio-filtration swales) and looking at new forms of urban greenery in regeneration projects and the protection and expansion of existing green spaces as a key component in regreening cities [43,44].…”

“…However, the potential problems arising from the deployment of in cities is usually overlooked. Urban trees contribute to considerably centration of harmful pollutants, but they may increase the concentra for example, ground-level ozone [44]. While planting trees in urban s and efficient way to adapt to climate change, it is not a holistic solutio An enormous number of studies have been published on the potential impact of additional urban vegetation on urban temperature, thermal comfort, pollution reduction, and health.…”

“…However, the potential problems arising from the deployment of additional greenery in cities is usually overlooked. Urban trees contribute to considerably decreasing the concentration of harmful pollutants, but they may increase the concentration of some others, for example, ground-level ozone [44]. While planting trees in urban spaces is an effective and efficient way to adapt to climate change, it is not a holistic solution [65].…”

“…Scientists have discovered that one square meter of green roof binds up to 10 g of fine dust per year and absorbs 375 g of CO 2 . In addition, green roofs reduce surface temperature and heat losses from buildings [44].…”

Ecosystem Services Provided By Urban Forests In The Southern Caucasus Region: A Modeling Study In Tbilisi, Georgia

“…Urban green spaces contribute to the absorption of carbon dioxide, remove gaseous pollutants and fine particulate matter from the air , mitigate extreme temperatures ( Santamouris and Osmond 2020) and the UHI (Urban heat island) effect by shading and the evapotranspiration (Rahman et al 2020), slow down soil erosion processes, reduce water run-off and facilitate the filtration process in the soil (Grey et al 2018), and preserve animal and plant biodiversity, promoting the pollination process with the breeding of various species and the biological control of populations (Dwyer et al 2003). In addition to environmental services, urban green spaces have an important social function because they are essential recreational and cultural spaces for the city , producing positive impacts on human health and wellbeing (Higgins et al 2019).…”