Implications of Off-Peak Commercial Deliveries for Air Quality and Environmental Justice.

Urban trucking poses significant health and environmental risks, particularly diesel-fueled trucks. Off-peak delivery (OPD), which refers to the delivery of goods during evening and overnight hours, provides an opportunity to mitigate traffic congestion and improve delivery efficiency. However, the impacts of this delivery schedule on population exposure to air pollution are not clear. This study investigates the spatial distribution of traffic-related air pollutants under two OPD scenarios and assesses their environmental justice implications, in the Greater Toronto and Hamilton Area (GTHA). Using truck movement information from a regional travel demand model and a chemical transport model, we estimated the diurnal changes in air pollutants. The OPD scenarios entail shifting the shares of delivery trips to the evening and overnight periods and account for induced passenger trips during the daytime, resulting from a reduction in truck traffic. One scenario was designed to reflect the industry sectors that would most likely participate in such a scheme and a realistic participation rate, while the other reflects an aggressive shift to overnight periods. While ambient air quality improves during the daytime, despite increased commuter traffic replacing truck movements, air pollutant concentrations worsen at night due to increased emissions under more stable atmospheric conditions. Under both scenarios, the most disadvantaged communities experience the highest variations in air pollution, as they often live close to highways and major truck routes.