When Jun Wu and her colleagues published a study in 2023 showing that exposure to neighborhood green space was associated with a lower risk of postpartum depression, the findings helped illuminate a powerful connection between environment and maternal mental health. Today, the UC Irvine professor is building on that work with an expanding research agenda that examines how a broad range of environmental conditions - from tree canopy and walkable neighborhoods to extreme heat and wildfire smoke - shape health outcomes for families.

Wu, a professor of environmental and occupational health in the Joe C. Wen School of Population & Public Health, has spent her career studying how environmental exposures affect reproductive and child health. Her research combines environmental epidemiology, advanced exposure assessment and population health data to understand how the places people live influence their well-being.

For the 2023 study, published in The Lancet Regional Health - Americas, Wu's team analyzed more than 415,000 electronic health records from healthy, full-term births in Southern California. The researchers found that women living in neighborhoods with greater exposure to green space - particularly tree coverage visible at street level - had a lower risk of postpartum depression. The work also suggested that physical activity during pregnancy may help explain part of the correlation between greener environments and improved mental health.

The research was among the first to explore multiple types of green space and their relationship to postpartum depression. It revealed that tree canopy appeared to offer stronger protective benefits than other forms of vegetation, highlighting the importance of how people experience nature in their everyday surroundings.

Since then, Wu's work has continued to deepen understanding of environmental influences on maternal health. Her research program has expanded beyond green space to investigate how air pollution, climate-related exposures and neighborhood conditions affect pregnancy outcomes and mental health among vulnerable populations.

That growing body of work received a significant boost in 2025 when Wu secured a National Institutes of Health grant to lead a major new study examining how environmental factors affect maternal and child mental health across Southern California. The project will explore the effects of exposure to extreme heat, wildfire smoke and other ambient stressors.

"Climate change doesn't just threaten our physical health - it can reshape how we think, feel and cope with everyday life. Our earlier findings suggested that green spaces may help buffer stress and support mental well-being," Wu said. "Now we're asking a larger question: As climate impacts intensify, how do we preserve and strengthen those protective environments so communities can remain healthy, resilient and connected?"

The new study is a natural corollary to Wu's green-space findings: If access to healthy environments can support mental well-being, how do environmental stressors undermine it?

The answers could have important implications for urban planning, public health policy and climate resilience strategies. As communities grapple with rising temperatures, worsening wildfire seasons and persistent health disparities, Wu's research is helping identify environmental factors that can either protect or threaten family well-being.

Her results increasingly point to a central theme: Environmental conditions are not merely background features of daily life - they are determinants of health.