Driving Under the Influence of Obesity: The External Costs and Benefits of Unhealthy Behaviors

Abstract

We explore the previously unidentified negative relationship between body mass index and the likelihood of involvement in an alcohol-related accident among all drivers in fatal motor vehicle accidents. This relationship is not explained by differences in driver attributes (e.g. age, gender), driver behaviors (e.g. speed, seat-belt use, etc), vehicle attributes (e.g. weight class, model year, number of occupants), or accident context (e.g county of accident, time of day, day of week, weather). We conclude that the physiological relationship between body mass and impairment produces a positive externality. We then estimate the magnitude of the external benefit of obesity using methods first implemented by Levitt and Porter (2001). Relative to the counterfactual scenario in which all obese Americans were instead non-obese in 2009, our preferred estimates imply that there was 2.8% fewer fatal drunk driving accidents and the total external benefit of obesity was $20.48 per obese driver.

Keywords: Obesity, Drunk Driving, Externalities

JEL Classification: H23, I18, K42