Cyclist wearing a pollution-mask in London (Credit: LeoPatrizi /iStock)

Many empirical studies have examined various determinants of crime. However, the link between crime and air pollution has, surprisingly, been overlooked, despite there being several potential pathways.

Using daily data for London, for the years 2004–5, the authors of this paper study whether exposure to ambient air pollution affects crime. They find that elevated levels of air pollution have a positive and statistically significant impact on overall crime and that the effect is stronger for types of crime that tend to be less severe. Having explored the underlying mechanism for this finding, they conclude that the effect of air pollution on crime is likely mediated by higher discounting of future punishment. Importantly, they also find that these effects are present at levels that are well below current regulatory standards and that the effect of air pollution on crime appears to be unevenly distributed across the income distribution.

These results provide evidence that environmental factors are an important determinant of crime. While previous studies focused on weather conditions, which are unlikely to be shaped by policymakers, the authors have studied an environmental condition, which can be regulated. The results suggest that improving air quality in urban areas through tighter environmental policy may provide a cost-effective way to reduce crime.

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