A new study from Northwestern University has examined the air quality, health implications at geographic scales. These are based on simulations designed to model traffic-related air pollution over the region surrounding Chicago, which act as North America’s largest freight hub.
The model simulates and quantifies pollution levels by neighbourhood, tracking hour-by-hour levels of nitrogen dioxide, ozone and particulate matter across areas as small as one kilometre. The simulations provide neighbourhood-scale estimates of air quality over the region by combining high-resolution emissions data with simulated meteorology to show how air pollutants chemically interact and accumulate — across time and space — throughout Chicago and surrounding areas.
This approach demonstrates where different pollutants form and how pollutants spread, interact with other gases and sunlight in the air and change according to seasons.
One of the inputs into the model was data from the American Community Survey which provided population and demographic data and incorporated mortality rates derived from health data.
In terms of modelling vehicles, this included tailpipe, refuelling and extended idling emissions from heavy-duty vehicles. Such vehicles included municipal buses, school buses, refuse trucks, short- and long-haul trucks and motor homes.
In terms of the outcomes, one scenario saw the researchers replace 30 percent of current on-road heavy-duty vehicles (HDVs) with electric HDVs. This showed that electrifying HDVs would substantially reduce air pollution and save hundreds of lives annually in the region, with particularly large health benefits in predominantly Black, Hispanic and Latinx communities.
Under these test conditions, such a reduction of traffic-related pollution would result in a decrease of about 590 premature deaths per year due to reduced nitrogen dioxide concentrations and a decrease of about 70 premature deaths per year from particulate matter reductions. Premature deaths from ozone, however, would increase by about 50 deaths per year.
In addition, the findings indicates that electrifying heavy-duty vehicles across the U.S. could help reduce long-standing environmental injustices related to pollutant impact disparities in major metropolitan areas.
While heavy-duty vehicles only constitute a small portion of the total on-road vehicle fleet (6 percent), they disproportionately contribute to the emission and creation of health-harming air pollutants and greenhouse gases. Heavy-duty vehicle sector is the largest contributor to on-road nitrogen oxides and second largest source of on-road carbon dioxide emissions.
Current progress towards the electrification of passenger vehicles remains important, given their sheer numbers; however, from an impact perspective it is important to incentivize, and perhaps prioritise, transitioning fossil fuel-powered heavy-duty vehicles to electric vehicles. The research appears in the journal Nature Sustainability, titled “Air quality, health and equity implications of electrifying heavy-duty vehicles.”
