Greenery is linked to Mental Health:- With the increase in the population, the pollution levels have increased in the urban regions. Living in a green space will benefit your health for sure. Increased life expectancy and reduced mental health issues are some of the factors. But it is unclear how much green space is required to benefit the health of a human being. As per the study led by IS Global, a centre supported by the "la Caixa" Foundation, conducted research between better mental health and a 3-30-300 green space rule. As per the report, every person should be able to see three trees from their home. They should have 30 percent tree canopy cover in the neighborhood and they should not live more than 300 metres away from the green space or the nearest park.

This rule has been proposed by urban forester Cecil Konijnendijk. The green space rule is clearly associated with a better mental health. The residential surrounding greenness is associated with a better mental health. The study said that 4.7 percent of the population met all the three criteria of the rule of the green space. 43 percent of the respondents had three trees within 15 metres to their home. 62.1 percent of them had a major green space within the limit of 300 metres. 8.7 percent off them lived with sufficient surroundings of greenness. 22.4 percent of them had no greenery. The study was based on 3145 inhabitants in Barcelona and they are aged in between 15 and 97 years.