How Does Pollen Affect Criminal Activity?

A simple model of crime suggests that a criminal will act when the benefits of committing the crime outweigh the costs. The benefits might include anything from financial gain to emotional release. The costs are also wide-ranging — from the obvious legal punishments to the more subtle ways in which criminal activity can be physically and emotionally harmful. Within this cost-benefit framework, researchers Aaron Chalfin, Shooshan Danagoulian, and Monica Deza examine the way in which seasonal allergies affect rates of criminal activity. By analyzing pollen and crime data in 16 cities, the authors aim to determine if there is any relationship between high-pollen days and crime, and if so, what potential mechanisms drive that relationship.

To study criminal outcomes, the authors use incident-level crime data from the National Incident Based Reporting System and publicly available data from city police departments. The authors also use data collected by the National Allergy Bureau measuring pollen from trees, grass, and weeds. Based on these data, the authors conduct a statistical analysis to determine how crimes committed per day vary with daily pollen counts, controlling for weather and the fixed effects of the individual cities studied. They find that on days with high pollen counts, there is approximately 4 percent less violent crime than on days with lower pollen counts.

Naturally, this poses an important question: Why are incidences of violent crime significantly lower on days with high pollen than those with low pollen? To answer this question, the authors delve into the research literature and settle on a number of potential mechanisms explaining the relationship. First, they suggest that seasonal allergies might force both criminals and potential victims to spend less time outdoors, decreasing the chance of an encounter and its associated criminal “benefits.” Second, they postulate that seasonal allergy affliction may impose additional physical costs on criminals through common symptoms or the side-effects of medication.

In order to evaluate this hypothesis, the authors look for confirmation that individuals spent more time indoors on high-pollen days. They use two data sources for their original analysis: CitiBike data in New York City and Google Trends for allergy-related topics. They find that, on high-pollen days, there is a significant increase in allergy-specific search terms. Furthermore, there is a slight decrease in CitiBike usage, although it is not statistically significant. The authors also reference additional studies showing that pollen allergies cause missed school days for teenagers and productivity losses in the workplace to indicate that individuals are more likely to stay home when the pollen count is high. Together, this research supports the authors’ hypothesis that seasonal allergy affliction imposes physical costs.

Understanding some of the environmental factors that affect crime may seem pointless to a policymaker, given that he or she cannot control the pollen count on any given day. Nonetheless, this research adds value for a number of reasons. First, it adds to our knowledge about the determinants of crime, especially in relation to how physical costs affect the likelihood of committing a crime. Second, it enhances the broader conversation on the effects of environmental conditions on human behavior. This conversation is especially pertinent in an era of climate change. Finally, policymakers might use this research to reconsider the allocation of police and other anti-crime resources during high-pollen days. This research about the relationship between seasonal allergies and crime is enlightening, and it adds value to our understanding of criminality.

Article source: Chalfin, Aaron, Shooshan Danagoulian, and Monica Deza, “More Sneezing, Less Crime? Health Shocks and the Market for Offenses,” Journal of Health Economics 68 (2019): 102230.

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