PEPH Newsletter | National Institute of Environmental Health Sciences

Spending time in green space perceived as high quality, like the natural environment or parks, can lower post-hurricane distress, according to a recent study that focused on Houston residents’ distress after Hurricane Harvey. The study results support paying more attention to neighborhoods’ green infrastructure in disaster recovery and city resilience planning.

“Exposure to a severe natural disaster is associated with increases in stress, anxiety, depression, and posttraumatic stress disorder. Access to green space can provide mental health benefits, such as decreases in stress and anxiety, and can improve physical health,” said Jennifer Horney, Ph.D., an NIEHS-funded epidemiologist and disaster researcher at the University of Delaware who collaborated on the study, which was funded through Texas A&M University’s Superfund Research Center. “But there was little research on access to greenness in the context of recovery from natural disasters, and we thought we could fill that gap.”

Hurricane Harvey, which hit the U.S. in August 2017, affected 12 million Gulf Coast residents with catastrophic flooding, displacement, and structural damage. Even a year after the hurricane, residents had mental health issues at higher levels than the U.S. average, according to a recent study.

Determining effective, wide-reaching post-disaster mitigation strategies is important for resilient city planning and equitable public health.

Surveying Houston Residents About Stress and Hurricane Exposure

Horney’s team surveyed Houston residents between August and December 2019, about two years after the hurricane. They focused on neighborhoods in which residents were heavily impacted by the hurricane and ensured their sampling was representative of socio-demographic conditions.

The team mailed survey packets and reminder postcards, and they later visited households in neighborhoods that had lower-than-average response rates. Altogether, they collected 272 valid responses, which equates to a response rate of 7.3%.

“Although the overall response rate was low, targeting neighborhoods that may have been less likely to respond was important,” reflected Horney. “These areas may also have residents who are less likely to be aware of programs that could provide support, financial or otherwise, to those impacted by Hurricane Harvey’s flooding.”

The Houston Resident Survey (top, left) and a team member working on preparing survey packets to mail to Houston residents (bottom, right). (Photo courtesy of Jennifer Horney)

The survey questionnaire asked residents to report on their experiences with the following:

  • Probable post-traumatic stress disorder (PTSD)
  • Hurricane-related distress
  • Hurricane exposure
  • Perceived quality of green space
  • Emotional resilience, which is the ability of someone to adjust and recover from stress and restore well-being and positive emotions
  • Neighborhood social cohesion based on inter-personal relationships
  • Covariates, such as education levels, employment status, and income

Hurricane-related distress was measured by self-reported symptoms such as difficulty sleeping or concentrating. Questions related to hurricane exposure asked about stressors an individual experienced during the hurricane, such as walking through floodwaters, having severe home damage, or seeing someone die. Questions related to the perceived quality of green space touched on various aspects, such as attractiveness, accessibility, and safety, and its potential for relaxation and neighborly activities. Overall, the perceived quality of green space measurement captured the quality of the environment most relevant to participants.

The researchers also measured the concentration of neighborhood green space using aerial images from the U.S. Department of Agriculture. The concentration metric provided an objective measure of how much green space residents are exposed to, ranging from none for areas that are completely barren of vegetation to very dense green space.

“We know that many factors contribute to how well an individual recovers from a hurricane, and that they’re complex,” said Horney. “So, we wanted to control for major variables – like socioeconomic status and how severe an individual’s exposure was to the hurricane. That would let us see more clearly the potential relationships between recovery and access to quality neighborhood green space.”

The Link Between Neighborhood Green Space and Recovery

Unsurprisingly, Horney’s team found that people who reported greater exposure to hurricane stressors had higher levels of hurricane-related distress and probable PTSD. They also found that emotional resilience, perceived quality of neighborhood green space, and social cohesion were each related to lower levels of distress. Residents’ perceived quality of green space was also linked to lower levels of probable PTSD, but concentration of green space was not.

“Our findings show that the restorative benefits of nature may depend on people’s actual access to and use of the space, not just the existence of green space, which is sometimes used post-disaster for debris storage or for staging of temporary housing,” said Horney. “But outside the context of natural disasters, there’s an environmental health disparity around access to green space. Ensuring all populations have access to high-quality green space is important so everyone can benefit.”

Horney’s team hypothesized that the beneficial effect of green space on lowering probable PTSD and levels of individual distress was related either to emotional resilience or social cohesion. To figure out which, they tested different statistical models based on the survey data. They found that emotional resilience, but not social cohesion, was the link between perceived quality of green space and distress symptoms.

The study’s findings have implications for public health, disaster recovery, and planning policies and point to positive environmental exposures as aiding recovery. Promoting positive environmental exposure is important, especially since a lot of post-disaster research has focused on green space contamination by floodwater and residents’ perception of the safety of using affected green space after flooding has receded.

“Access to restorative environments such as high-quality green space should be a part of the health disparities discussions after disasters,” said Horney. “Our findings raise the possibility that community green space as a low-cost public amenity can be used to reduce inequalities and promote mental well-being and preparedness for at-risk populations.”

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