Higher density of natural gas pipelines overall occurs in counties with more socially vulnerable populations, according to analysis led by North Carolina State University researchers. This puts these already vulnerable counties at greater risk of public health and safety issues including water and air pollution, among other negative impacts associated with pipelines, the findings suggest.

"We know that the network, as it stands today, is already distributed in such a way that any negative impacts fall disproportionately on vulnerable communities," said the study's lead author, Ryan Emanuel, a professor of forestry and environmental resources at NC State. "Right now, when regulators evaluate the social impacts of these projects, they are treated in isolation, and not as part of a massive network that affects more than 70 percent of all the counties in the U.S."

The researchers measured social vulnerability according to a 2018 index created by the U.S. Centers for Disease Control and Prevention to assess 3,142 U.S. counties. Data on factors including household composition, age, disability status, race or ethnicity, and language quantified a county’s ability to recover after a disaster. The researchers combined this information with data from the U.S. Energy information administration to determine how the roughly 229,000 miles of pipeline network connect with counties identified by their social vulnerability scores.

Looking at the nearly 72% of counties that have pipelines, the researchers found a correlation between higher social vulnerability scores and pipeline infrastructure density.

"We studied the gas gathering and transmission pipelines, which are the really large and high-pressure pipelines that are meant to transport natural gas across regions or the country," Emanuel said. "We know that every year, there are explosions on transmission pipelines, and we have records for those accidents above a certain size. There are also air quality impacts at compressor stations that power them, and environmental damages that occur during construction."

Population density is a factor in the regulatory process used to evaluate the negative impacts of pipelines on a community, but it overlooks the way pipelines impact vulnerable rural communities. "Rural issues are not less intense versions of urban issues. We also know from past research that these projects can have a destabilizing influence on rural communities," Emanuel said.

The study also examined the issue in terms of social justice, highlighting the impacts pipeline infrastructure have on indigenous communities. In addition to pollution and health risks, pipelines create risks for cultural harm in areas with religious, historical or cultural significance.

The researchers indicated the need for federal regulators to assess the location of infrastructure networks, including existing pipelines, to avoid reinforcing historic oppressive practices in the future.

The research is published in the journal GeoHealth.