Is indoor and outdoor greenery associated with fewer depressive symptoms during COVID-19 lockdowns? A mechanistic study in Shanghai, China.

Increasing numbers of studies have observed that indoor and outdoor greenery are associated with fewer depressive symptoms during COVID-19 lockdowns. However, most of these studies examined direct associations without sufficient attention to underlying pathways. Furthermore, few studies have combined different types of indoor and outdoor greenery to examine their effects on the alleviation of depressive symptoms. The present study hypothesized that indoor and outdoor exposure to greenery increased the perceived restorativeness of home environments, which, in turn, reduced loneliness, COVID-related fears, and, ultimately, depressive symptoms. To test our hypotheses, we conducted an online survey with 386 respondents in Shanghai, China, from April to May 2022, which corresponded to strict citywide lockdowns that resulted from the outbreak of the Omicron variant. Indoor greenery measures included the number of house plants, gardening activities, and digital nature exposure as well as semantic image segmentation applied to photographs from the most viewed windows to quantify indoor exposure to outdoor trees and grass. Outdoor greenery measures included total vegetative cover (normalized difference vegetation index [NDVI]) within a 300 m radius from the home and perceived quality of the community's greenery. Associations between greenery and depressive symptoms/clinical levels of depression, as measured by the Patient Health Questionnaire-9 (PHQ-9), were examined using generalized linear and logistic regression models. Structural equation modeling (SEM) was used to test pathways between greenery exposure, restorativeness, loneliness, fear of COVID-19, and depressive symptoms. The results showed that: 1) indoor and outdoor greenery were associated with fewer depressive symptoms; 2) greenery could increase the restorativeness of the home environment, which, in turn, was associated with fewer COVID-related mental stressors (i.e., loneliness and fear of COVID-19), and ultimately depressive symptoms; and 3) gender, education, and income did not modify associations between greenery and depressive symptoms. These findings are among the first to combine objective and subjective measures of greenery within and outside of the home and document their effects on mental health during lockdowns. Comprehensive enhancements of greenery in living environments could be nature-based solutions for mitigating COVID-19 related mental stressors.

Effects of urban parks on residents' expressed happiness before and during the COVID-19 pandemic.

The COVID-19 pandemic has impacted human health worldwide. In these unprecedented times, the benefits of urban parks for residents have gained attention. However, few studies have explored the effects of urban parks on residents' expressed happiness from the perspective of big data, and fewer have further deciphered the disparities between residents' expressed happiness before and during the pandemic. In this study, we explored the effects of urban parks on residents' happiness by including nine independent factors in baseline regression models, and chose 577 urban parks in Nanjing City, China, as study sites. Around 600,000 geotagged posts crawled on Sina Weibo (Chinese Twitter) were employed to obtain residents' expressed happiness. The results demonstrated that residents with access to urban parks with higher normalized differential vegetation index (NDVI) values are likely to be happier; and subdistrict-scale urban parks have the highest positive association with residents' expressed happiness. The presence of water, relatively dense populations, low land surface temperatures, and a low proportion of impervious land in the living environment were significantly associated with the higher expressed happiness of residents. The research period was divided into before and during the pandemic, and we identified that the positive association between NDVI of urban parks and residents' expressed happiness increased by one-half during the pandemic period compared to the overall results (0.372 vs. 0.255), indicating that the COVID-19 pandemic awakened Chinese residents' longing for high "green quality" urban parks. Our findings can provide guidance and recommendations for health-oriented urban park planning and design.