Spatial distribution of unconventional gas wells and human populations in the Marcellus Shale in the United States: Vulnerability analysis

Modern forms of drilling and extraction have recently led to a boom in oil and gas production in the U.S. and stimulated a controversy around its economic benefits and environmental and human health impacts. Using an environmental justice paradigm this study applies Geographic Information Systems (GIS) and spatial analysis to determine whether certain vulnerable human populations are unequally exposed to pollution from unconventional gas wells in Pennsylvania, West Virginia, and Ohio. Several GIS-based approaches were used to identify exposed areas, and a t-test was used to find statistically significant differences between rural populations living close to wells and rural populations living farther away. Sociodemographic indicators include age (children and the elderly), poverty level, education level, and race at the census tract level. Local Indicators of Spatial Autocorrelation (LISA) technique was applied to find spatial clusters where both high well density and high proportions of vulnerable populations occur. The results demonstrate that the environmental injustice occurs in areas with unconventional wells in Pennsylvania with respect to the poor population. There are also localized clusters of vulnerable populations in exposed areas in all three states: Pennsylvania (for poverty and elderly population), West Virginia (for poverty, elderly population, and education level) and Ohio (for children).