A recent report by Dutch researchers found lower rates of anxiety, depression, and other illness among people who live in the vicinity of gardens, parks, and other green spaces. Although previous studies have shown a relationship between patients' perceptions of their health and well-being and their proximity to nature, this is the first to demonstrate the same with specific, physician-assessed diseases.

The researchers gathered data on 345,143 patients from the electronic medical records of general practitioners in the Netherlands. They determined the extent of green spaces within one and three kilometers of the homes of the subjects, matching a national database of all types of land cover in the country with the patients' postal codes, and analyzed prevalence rates of disease clusters among the patients. What they found was that people living in areas with more green space within a single kilometer of their homes had lower rates in 15 of the 24 disease-cluster categories. Mental disorders, including depression and anxiety, showed the strongest relationship; the annual prevalence of anxiety among those with 10% green space in a 1-km radius was 26 per 1000 people; among those with 90% green space in the same radius it was 18 per 1000. For depression, these figures were, respectively, 32 and 24 per 1000. Notable differences were also found with respiratory illnesses, neurologic disorders, and other diseases. The impact was greatest in children younger than 12 and those with lower income-perhaps, the authors theorize, because they spend the most time close to home.

Although the benefits of nearby green space were obvious in slightly urban areas, they were less so in highly urban areas. This, researchers believe, could be because green spaces in those areas "evoke feelings of insecurity." In other words, if a park across the street doesn't feel safe, it's unlikely to be used or to improve the quality of one's health.

The reasons for the health benefits of green space were not made entirely clear. The bolstering of mental health may be a function of stress relief and the easy social opportunities that parks and similar spaces provide; and better air quality likely contributes to lower rates of respiratory illness. The encouragement of physical activity also can't be dismissed as an advantage, although the researchers found evidence supporting such a connection to be weaker.

"Our study contributes to the evidence that green space can help fight some major public health threats in Western societies," write the authors. "Healthy spatial planning should take the amount of green space in the living environment into account when endeavouring to improve the health situation, particularly of children and lower socioeconomic groups."

Laura Wallis