The urban environment has been proposed to be a key health determinant worldwide. Half of the global population lives in urban environments, and changes to urban design, such as the introduction of green spaces, have been suggested to improve population health.1–8 Green spaces are associated with more physical activity, physical or mental restoration and reduced stress, higher social capital, and ecosystem services, such as better air quality, less traffic noise, less heat-island effects, and more biodiversity.
Green spaces have also been associated with better mental health, and benefits to the immune system and to metabolism, improved pregnancy outcomes, a reduction in cardiovascular disease, and reduced premature mortality. However, green spaces are also linked to some health risks, such as exposure to allergens (such as pollen), pesticides, herbicides, vector-borne diseases transmitted by arthropods (such as Lyme disease or dengue), accidental injuries due to activities performed in green space areas, and excessive exposure to ultraviolet radiation.But, overall, most of the epidemiological evidence indicates that exposure to green spaces could result in health benefits.