The state of modelling for evaluating health equity impacts of freight emissions

Evaluating health equity impacts of freight emissions is crucial for developing a sustainable and just freight system. It is a complex process that requires interdisciplinary knowledge, including transportation, environment, and public health. Full-chain simulation is an important approach for forecasting freight planning outcomes. However, a systematic framework that integrates available models in full-chain and is specifically designed for the freight sector has not been developed. We review 36 empirical studies covering this interdisciplinary topic, and summarise the commonly used models. We find that EMission FACtor (EMFAC) and Motor Vehicle Emission Simulator (MOVES) models are commonly used to estimate freight vehicle emissions, with their outputs serving as inputs for air quality models, such as Community Multiscale Air Quality Model (CMAQ) or Intervention model for air pollution (InMAP). To estimate the health effects, concentration-response (C-R) functions, combined with static or dynamic demographic and socioeconomic data, are used to quantify the relationship between changes in pollutant concentrations and health outcomes. Then, disparity analysis relies on the assumption of age-specific C-R functions and examines statistical differences between demographic groups – including racial/ethnic groups, income levels, age groups, and other vulnerable communities. This study comprehensively outlines this state-of-the-art, integrated framework identified through the synthesis of this interdisciplinary literature. This framework can support future researchers in this field and policymakers.