Is green space associated with opioid-related mortality? An ecological study at the U.S. county level

Abstract

Opioid consumption, both legal and illicit, has risen precipitously in the U.S. over the past few decades, as has the number of deaths due to the use and misuse of opioids. Exposure to green spaces may help to alleviate the problematic levels of opioid use. Such exposure has been tied to health benefits relevant to opioid use. To explore the potential influence of green space on opioid-related health outcomes, we analyzed the association between tree canopy cover and mortality attributable to opioid use and abuse using 2008–2018 death rate data on a county level (n = 3087) across the contiguous U. S. We fitted spatial general additive model while controlling for socioeconomic factors, healthcare access measures, opioid prescription rates, and particulate air pollution. Contrary to expectations, canopy cover was positively associated with opioid mortality. A sensitivity analysis with forest land cover showed similar results while a sensitivity analysis with total greenness (NDVI) was nonsignificant. Stratified models by urbanicity level suggested suburban and rural counties drove the positive associations observed in the nationwide models. The findings for forest and canopy cover are unexpected, given the myriad health benefits of green spaces, yet might be explained by heavily forested areas (i.e., Appalachia) being home to injury-prone natural resource extraction employment sectors. The steady decline of these industries has created poor socioeconomic conditions that exacerbate the already elevated risk of opioid use and misuse. Alternatively, the magnitude of the protective effects of greenspace on pain reduction are insufficient to counter opioid demand. Further research is warranted, especially in studies with individual-level data. Entities with responsibility or interest in reducing the incidence of deaths from opioids are cautioned that green spaces might not be a viable option for reducing opioid mortality.