A new study suggests that greener surroundings may help reduce hospital admissions for mental health disorders across several countries. The research, published Nov. 5 in The BMJ, found a clear link between local greenness and lower mental health risks.
Researchers led by Tingting Ye, Ph.D., from Monash University in Melbourne, analyzed data from 6,842 locations in seven countries: Australia, Brazil, Canada, Chile, New Zealand, South Korea, and Thailand. Their study covered 11.4 million mental health hospital admissions between 2000 and 2019.
The study showed that a 0.1 increase in the Normalized Difference Vegetation Index, a measure of greenness, was linked to a 7 percent decrease in the risk of hospital admissions for mental disorders.
However, the effect varied by country and type of disorder. Brazil, Chile, and Thailand showed consistent protective effects, while modest adverse associations appeared in Australia and Canada across certain disorder categories.
The researchers found a generally linear relationship between greenness and mental health without a clear threshold. Urban areas showed more consistent results, with an estimated 7,712 mental health admissions each year statistically linked to greenness levels. A 10 percent rise in local greenness was tied to fewer hospital admissions — from about 1 per 100,000 people in South Korea to about 1,000 per 100,000 in New Zealand.
The authors note that differences between countries, climates, and mental disorder types highlight the importance of tailored, local approaches when assessing the influence of environmental greenness on mental health outcomes.
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