An increase in air pollution could contribute to violent crime in urban areas, according to research by Evan Herrnstadt of Harvard University and Erich Muehlegger of the University of California, Davis.
Comparing more than 2 million crimes reported to the Chicago Police Department between 2001 and 2012 with pollution data, the researchers find no correlation between air quality and property crimes such as burglary, robbery, larceny, arson, and grand theft auto. However, violent crimes, including homicide, forcible rape, assault, and battery, rose 2.2 percent in areas dealing with local air pollution temporarily increased by environmental conditions.
“This discrepancy across crime types may suggest that the primary mechanism is physiological; that is, the pollution might make people more irritable and impulsive, thus leading to more violent crime,” the researchers write.
The principal cost of violent crime is, of course, measured in human terms, paid for by the victims whose lives are lost and destroyed by violence. But the researchers also attempt to estimate the cost in dollars, using tangible costs of crimes such as medical expenses, cash losses, and lost earnings.
In Chicago, they estimate that the cost of violent crime attributable to the effect of pollution runs to more than $81 million a year, almost all of it accounted for by homicide—and this is only counting crimes within a mile of major interstates. If they assume that the violent crimes are limited to assault and battery, the annual estimate falls to $1.8 million.
To control for changes that could be connected to days of the week or weather, the researchers used wind direction around highways to analyze areas that had differing levels of pollution at the same time.
Since vehicles are a source of significant air pollution, the researchers looked at days on which the wind was blowing perpendicular to interstate highways transecting Chicago. On those days, neighborhoods upwind had less pollution, and neighborhoods downwind had more.
“We are able to flexibly control for day-to-day unobservables correlated with crime that we might be concerned would bias city-level estimates,” the researchers write.
The findings will be of interest to the US Environmental Protection Agency, which typically looks at the direct health impact of exposure to pollutants when it assesses the costs and benefits of environmental regulation.
“While the authors only did ‘back-of-the-envelope’ estimates of the cost of the additional crime, it certainly seems potentially substantial enough for EPA to consider in its cost-benefit analyses,” Seth D. Jaffe, a partner at Foley Hoag LLP, a law firm specializing in environmental litigation, said in a blog post.
Evan Herrnstadt and Erich Muehlegger, “Air Pollution and Criminal Activity: Evidence from Chicago Microdata,” NBER working paper, December 2015.