Co-benefits from reduced car travel in the Midwestern United States

Background:

Automobile exhaust contains fine particulate matter and precursors to ozone, posing health risks.

Objective:

To quantify health and economic benefits from reducing automobile usage for short urban trips.

Methods:

Using census tract-level mobile emissions estimates, we remove short automobile round-trips less than 8 kilometers from 11 midwestern metropolitan areas and simulate changes in hourly pollutant concentrations, then estimate annual health and monetary outcomes from pollution reductions using the Community Multiscale Air Quality (CMAQ) Model and EPA's Benefits Mapping Analysis Program (BenMAP). We use WHO's Health Economic Assessment Tool (HEAT) to calculate benefits of increased physical activity.

Results:

Mortality declines 1,111 deaths/year (95% CI: 856 – 1,346), 38% from improved air quality and 62% to improved health from bicycling. Annual average urban PM2.5 declines 0.1 µg/m3, while summer O3 increases slightly in cities but declines regionally. PM2.5 and O3 changes yield extensive economic benefits, with 25% of PM2.5 and most O3 benefits being outside metropolitan areas. Economic benefits from bicycling surpass those from air quality improvements. The combined benefit from improved air quality and physical fitness is billions of dollars per year.

Conclusion:

Significant health and economic benefits are possible if bicycling replaces short car trips. Less auto dependence also improves health in downwind rural settings.