Is the Environmental Exposure Gap Shrinking? Evidence from an Extreme Multi-exposure Index

Demographic disparities in exposure to various sources of environmental stress are well documented. While specific stressors are linked to adverse health outcomes, there is uncertainty about how they interact. A first step towards evaluating these joint impacts is to understand the degree to which the same individuals are exposed to extreme simultaneous exposure to each stressor. Here, we adapt the Alkire-Foster multi-dimensional poverty measure to rank exposures to multi-dimensional environmental harm in a way that accounts for the frequency, breadth, and severity of exposure among the extremely exposed. This measure can be used to normatively compare distributions of extreme simultaneous exposure for a given group both across time and in comparison with other groups. We use publicly-available data on air toxics, PM2.5, and land surface temperature to identify trends in the multi-exposure index for socio-demographic groups based on race/ethnicity and poverty status for 168 U.S. cities. Controlling for city-characteristics, we find persistent, yet narrowing, multi-exposure gaps on the basis of race/ethnicity between people of color (POC) and non-Hispanic White. Within each group, individuals in households above the poverty line fare better than those below, but above-poverty POC have similar multi-exposure to below-poverty non-Hispanic White.