Environmental health, racial/ethnic health-disparity, and climate impacts of freight transport in the United States

Abstract

BACKGROUND AND AIM: Atmospheric emissions from freight transportation contribute to human health and climate damage. In this research, we quantify and compare three environmental impact types from inter-regional (inter-state) freight transportation in the contiguous United States (U.S.): mortality from fine particulate matter (PM₂.₅), racial-ethnic disparities in mortality, and climate impacts (CO₂ emissions). METHODS: We compare all major modes (truck, rail, barge, aircraft), all major routes (~30,000 routes; ~90% of 2017 annual freight tonne-km). Our analyses use freight movement and geospatial data from the U.S. Department of Transportation, modal routing to identify shortest routes from origin to destination, and air quality and health impact modeling using a high spatial resolution air quality model, the Intervention Model for Air Pollution (InMAP). RESULTS:Impacts (health, health-disparity, climate) per tonne are largest for aircraft. Among non-aircraft modes, per tonne, rail has the largest health and health-disparity impacts, and the lowest climate impacts; truck has the lowest health impacts and greatest climate impacts – an important reminder that health and climate impacts are not always aligned. These results represent 84%, 99%, 97%, and 98% of total annual truck, rail, barge, and air tonne-km, respectively. For aircraft, average monetized damages per tonne are larger for climate impacts than for PM₂.₅ air pollution impacts; for the other modes, the reverse holds. We find that average exposures from inter-state truck and rail are the highest for white non-Hispanics, from barge is highest for blacks, and from aircraft is highest for mixed/other race groups. Level of exposure and disparity among racial-ethnic groups vary in urban and rural areas. CONCLUSIONS:Our study is the first to compare each route separately, and the first to explore racial-ethnic exposure disparities by route and mode. This research can be used to inform, for many origins and destinations, which freight mode offers the lowest environmental health, health-disparity, and climate impacts. KEYWORDS: Air Pollution, Particulate Matter, Exposure assessment, Climate, Environmental justice