Green spaces improve mental health by mitigating effect of long-term NO2 exposure

A new study published in the Journal of Psychiatric Research shows that particularly in places with low levels of long-term NO2 exposure, green spaces may mitigate the acute effect of NO2 exposure on hospitalizations for mental disorders.

The primary environmental factor contributing to premature death, according to the World Health Organization, is air pollution. Psychiatric disorders are the second-largest cause of years spent with disabilities (32%) and the second-largest contributor to the global disease burden. In contrast to green areas, which have been associated with better mental health, air pollution is a risk factor for an increase in hospital admissions for mental illnesses. In order to link daily hospital admission data from Wuhan's 74 municipal hospitals from 2017 to 2019, Can Yang and colleagues used a land use regression model (LUR) to incorporate data on the residential surrounding green areas with 250 m and 500 m buffers based on the normalized difference vegetation index (NDVI).

In order to explore the modification effect of long-term NO2 exposure and green spaces, stratification analyses were used to estimate the odds ratios in the single- and dual-environmental factor groups. The conditional logistic regression model was used to estimate the acute effect of short-term NO2 exposure.

The key findings of this study were:

1. There were 42,705 hospital admissions for mental illnesses in total. Short-term NO2 exposure was linked to a higher incidence of mental illness-related hospital admission.

2. An increase in hospital admissions for all mental illnesses of 2.86% was linked to a 10 g/m3 rise in NO2 (lag01 day).

3. Patients in the "high-NDVI/low-NO2" group had a decreased and negligible rise in hospitalizations for all mental illnesses when compared to patients in the "low-NDVI/low-NO2" group, whereas greenness had a minor moderating impact in the high-level, long-term NO2 exposure areas.

In conclusion, It has been suggested that air pollution and climate change in general affect mental health through promoting neuroinflammation, disrupting neuronal signaling, and lowering immunological reactivity. A risk factor for mental diseases, including sadness, anxiety, and psychoses, is urban life without natural areas.

Reference:

Yang, C., Wang, J., Yang, H., Liao, J., Wang, X., Jiao, K., Ma, X., Liao, J., Liu, X., & Ma, L. (2022). Association of NO2 with daily hospital admissions for mental disorders: Investigation of the modification effects of green spaces and long-term NO2 exposure. In Journal of Psychiatric Research (Vol. 156, pp. 698–704). Elsevier BV. https://doi.org/10.1016/j.jpsychires.2022.11.014