The world is getting hotter and more crowded, as climate change and urbanization are transforming the planet. More than half of the global population now lives in cities, and this proportion is expected to increase to 68% by 2050.
However, urban living comes with a cost: exposure to higher temperatures, air pollution, noise, and stress, which can affect human health and well-being.
One of the ways to cope with these urban challenges is to create more green spaces in cities.
Green spaces, such as parks, gardens, and street trees, can offer multiple benefits for urban residents, such as improving air quality, enhancing biodiversity, reducing noise, and providing recreational opportunities.
But perhaps the most important benefit of green spaces is their ability to save lives, especially during extreme heat events, which are becoming more frequent and intense due to climate change.
The benefits of greenery for human health
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As the world faces the challenges of climate change, extreme heat events are becoming more frequent and intense, posing a serious threat to human health and well-being.
According to the World Health Organization, heat stress is linked to increased mortality from cardiovascular, respiratory, and renal diseases, as well as heat stroke and dehydration.
However, not all urban areas are equally vulnerable to the effects of extreme heat. Some landscape features, such as green spaces, can offer a cooling effect and reduce the risk of heat-related illnesses and deaths.
Green spaces, such as parks, gardens, and street trees, can provide shade, evaporate water, and create air circulation, thus lowering the ambient temperature and creating a more comfortable microclimate.
A recent study by researchers from China, South Africa, and the UK has shown that green spaces can have a remarkable protective effect on human health, especially under longer and more intense heat waves.
The study, published in the journal Environmental Health Perspectives, analyzed mortality, meteorological, and land use data from Hong Kong, a city with hot and humid summers and high building and population density.
The researchers found that living in an area with more green spaces was associated with a lower risk of heat wave-related mortality, compared to living in an area with less green spaces.
The effect was stronger for overhead-view greenery, such as trees and shrubs than for eye-level greenery, such as grass and flowers.
The study also found that other urban landscape features, such as building density and land surface temperature, had a significant impact on heat wave mortality associations.
Areas with higher building density and higher nighttime land surface temperature were associated with a higher risk of heat wave-related mortality, as they tend to trap more heat and prevent cooling at night.
The findings of the study provide scientific evidence for the importance of incorporating green spaces into urban planning and design, as a way of enhancing the resilience and adaptability of cities to extreme heat events.
The researchers suggested that different types of greenery should be considered for different purposes and locations, depending on the local climate and urban morphology.
For example, trees and shrubs can be planted along streets and in public spaces, to provide shade and cooling for pedestrians and residents.
Grass and flowers can be used in rooftops and balconies, to reduce the heat absorption of buildings and improve the aesthetic quality of the urban environment.
Green spaces can also be integrated with other urban infrastructure, such as water features, ventilation corridors, and renewable energy systems, to create a more sustainable and livable city.
The researchers also emphasize the need for more public awareness and education on the benefits of green spaces for human health and well-being, as well as the potential risks of extreme heat events.
They suggest that public health interventions, such as heat warning systems, heat shelters, and heat health action plans, should be implemented and coordinated with urban planning and design strategies, to reduce the vulnerability and exposure of urban residents to heat stress.
The study demonstrates that urban green spaces can save lives, according to urban big data.
By creating a more natural and comfortable urban environment, green spaces can not only mitigate the negative impacts of extreme heat but also enhance the overall quality of life and well-being of urban dwellers.
