In this article, I propose a nonlinear (bell-shaped) relationship between air pollution and criminal behavior. Exposure increases criminality by raising criminals’ taste for risk and violent behavior while also reducing it by changing the number of felons and crime opportunities in the market through exacerbated morbidity and avoidance behavior. I illustrate both mechanisms with a prospect-theory model of the decision to delict and a simplified search and matching frictions model between criminals and crime opportunities. Linear, quadratic, and nonparametric Poisson MLE panel models confirm this bell-shaped relationship for Mexico City and New York, suggesting that the positive effect of pollution on criminality uncovered by late studies may be better modeled with a non-linear model. Notably, the point at which the non-linear function maximizes criminality lies within the Environmental Protection Agency’s limit thresholds for dangerous exposure between sensitive groups and the general population.