The paper doesn't seem to be freely available; there's just the abstract. The first sentence of the abstract mentions "short-term". So I think what they've dete

The paper doesn't seem to be freely available; there's just the abstract. The first sentence of the abstract mentions "short-term". So I think what they've detected is that in a given locality people get violent when the air is dirty, which is not surprising, of course, but it's interesting to have an estimate of the magnitude of that effect. One would like to know for comparison what the magnitude of the effect of humidity and temperature is on violent crime. Those numbers are probably in the paper somewhere because the abstract mentions how they had to "address confounding variation between temperature and air pollution". It not being mentioned in the abstract makes me suspect that the effect of pollution on violent crime is probably rather small compared to the effect of weather on violent crime. (Is there a positive correlation between people stating stupid banalities and violent crime? Probably there is, because people who parrot things like "Correlation does not imply causation" tend to get punched in the face. For the avoidance of doubt, that was a joke, not a veiled threat.) EDIT: The last sentence of the abstract strikes me as highly questionable (though perhaps there's something in the paper to justify it). Just because there's a short-term correlation between pollution and violent crime doesn't mean that there will be a long-term correlation with a similar magnitude. In other words: if you reduce pollution globally over the next ten years people might just raise their expectations and be just as violent on the days on which pollution is relatively high as they were ten years previously.