The nexus between urban green space, housing type, and mental health

Momentum for urban densification is increasing opportunities for apartment-living, but can result in reduced green space availability that negatively influences mental health. However, in contexts where apartment-living is atypical and commonly viewed as secondary to house-ownership, it may be a stressful antecedent condition (or marker of selective processes aligned with psychological distress) wherein occupants could benefit disproportionately from green space.

Data were extracted from the Sax Institute's 45 and Up Study baseline (2006-2009, n = 267,153). The focus was on subsets of 13,196 people living in apartments and 66,453 people living in households within the cities of Sydney, Newcastle and Wollongong. Multilevel models adjusted for confounders tested associations between psychological distress (Kessler 10 scale) with percentage total green space, tree canopy and open grass within 1.6 km road network buffers.

Psychological distress was higher in occupants of apartments (11.3%) compared with houses (7.9%). More green space was associated with less psychological distress for house-dwellers (OR = 0.94, 95% CI = 0.91-0.98), but there was no association for apartment-dwellers. More tree canopy was associated with lower psychological distress for house-dwellers (OR = 0.88, 95% CI = 0.85-0.92) and apartment-dwellers (OR = 0.87, 95% CI = 0.79-0.96). Open grass was associated with more psychological distress among house-dwellers (OR = 1.06, 95% CI = 1.00-1.13) and also for apartment-dwellers (OR = 1.20, 95% CI = 1.07-1.35).

Overall, investments in tree canopy may benefit the mental health of house and apartment residents relatively equally. Urban tree canopy in densely populated areas where apartments are common needs to be protected. Further work is needed to understand factors constraining the prevention potential of open grass, to unlock its benefits for mental health.