Impacts of compact growth and electric vehicles on future air quality and urban exposures may be mixed

- Impacts of urban design on future air quality and exposure were investigated.
- Compact urban form was predicted to have lower area-wide emissions than sprawl.
- Compact form lowered NOx exposure but increased exposure to butadiene and benzene.
- Electric vehicles increased NOx exposure, but lowered exposure to the other pollutants.
- Multiple pollutants and source types need to be considered during urban design.

'Smart' growth and electric vehicles are potential solutions to the negative impacts of worldwide urbanization on air pollution and health. However, the effects of planning strategies on distinct types of pollutants, and on human exposures, remain understudied. The goal of this work was to investigate the potential impacts of alternative urban designs for the area around Tampa, Florida USA, on emissions, ambient concentrations, and exposures to oxides of nitrogen (NOx), 1,3-butadiene, and benzene. We studied three potential future scenarios: sprawling growth, compact growth, and 100% vehicle fleet electrification with compact growth. We projected emissions in the seven-county region to 2050 based on One Bay regional visioning plan data. We estimated pollutant concentrations in the county that contains Tampa using the CALPUFF dispersion model. We applied residential population projections to forecast acute (highest hour) and chronic (annual average) exposure. The compact scenario was projected to result in lower regional emissions of all pollutants than sprawl, with differences of − 18%, − 3%, and − 14% for NOx, butadiene, and benzene, respectively. Within Hillsborough County, the compact form also had lower emissions, concentrations, and exposures than sprawl for NOx (− 16%/− 5% for acute/chronic exposures, respectively), but higher exposures for butadiene (+ 41%/+30%) and benzene (+ 21%/+9%). The addition of complete vehicle fleet electrification to the compact scenario mitigated these in-county increases for the latter pollutants, lowering predicted exposures to butadiene (− 25%/− 39%) and benzene (− 5%/− 19%), but also resulted in higher exposures to NOx (+ 81%/+30%) due to increased demand on power plants. These results suggest that compact forms may have mixed impacts on exposures and health. 'Smart' urban designs should consider multiple pollutants and the diverse mix of pollutant sources. Cleaner power generation will also likely be needed to support aggressive adoption of electric vehicles.

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